The Performance Digest - October 2022 (Issue 72)

P E RFORM A N C E

Study Details

How to Read Me!

Praccal Takeaways from study

Related links to learn more about the topic

Reviewers comments on the st udy

C o nte nts

Research Reviewers

Fatigue & Recovery

Matthew is a Physical Therapist and the Clinical Director at a private Physical Therapy clinic in NYC. He has a special interest in the treatment of lower extremity/foot and ankle injuries along with helping runners and walkers to get back to what they love to do.

Youth Development

Tom is the Head of Athletic Development at St Peters RC High School. He holds a Masters in S&C and has previously worked with West Bromwich Albion FC, Gloucester Rugby club, and Great Britain Equine. Tom is our youth research reviewer at Science for Sport.

Technology & Monitoring

Cody is a strength and conditioning coach and adjunct lecturer at the University of Iowa. He has an MSE in Exercise Science from the University of Kansas and also holds a CSCS from the NSCA.

Coaching Science

Tom is currently an assistant professor in applied sports sciences and has worked in elite sport for over 10 years. Previous roles include working as a sports scientist at Liverpool FC, where he completed his PhD, and working across a number of other sports. He is passionate about physiology and has published papers on strength and conditioning, nutrition and youth development

Nutrition

James is a Performance Nutritionist for the English Football Association and works alongside the England national teams (men's and women's). He is also a SENr registered performance nutritionist and holds a PhD from Liverpool John Moores University.

Dr. Jordan August DPT, CSFC, SFMA, FMS

Injury Prevention & Rehab

Jordan is a Physical Therapist and Strength Coach who currently practices in a Sports & Orthopedic clinic in Bergen County, New Jersey. He is passionate about educating athletes on ways to optimize performance while decreasing the risk of injury.

Tom Green MSc UKAD Advisor

Dr. James Morehen PhD

Cody Roberts MSE

Tom Brownlee PhD

Matt Klayman’s MSE

C OA C H IN G

U sing co gnitiv e appraisal fo r adapting to stre ss in so cce r

Psychological stress is something that impacts daily life for all. It can be understood as a set of negative reactions and feelings in response to difficult situations. Those involved with sport are not immune from stress, and in youth sport it has been associated with anxiety, fear of failure, reduced selfconfidence, and burnout.

When looking to adapt to stress, the Transactional Stress Model suggests consideration should be given to the stressors that trigger the situation, how the situation is evaluated by the individual (cognitive appraisal) and the feelings that emerge from the situation. Building on this model the Interactive Model of Adaptation to Stress argues that adaptation can only begin if the stressors are considered important in relation to personal goals.

As such, this study aimed to analyse the mediating role of cognitive appraisal in the relationship between competitive stressors and emotional experience, as well as the moderating role of competitive level in the relationship between competitive stressors, cognitive appraisal, and emotions in young soccer players.

This study employed a cross-sectional methodology to examine 352 young male soccer athletes, aged between 15 and 19 (16.91 ± 0.99 yrs.), who were competing in the national football championship of Portugal.

The Questionnaire of Competitive Stressors in Sport (QCSS) was used to evaluate the potential sources of stress associated with the athletes’ performance. Athletes were asked to evaluate the level of stress from 0 (no stress) to 4 (very stressful) from 24 statements categorised as relating to competitive readiness, performance, errors, social expectations, opponents, and injuries.

A final score was given based on the average of these items.

To understand cognitive appraisal, the Primary and Secondary Cognitive Appraisal Scale (PSCAS) was used. The instrument consisted of 15 items to look at primary (importance, threat, and challenge perception) and secondary (coping, and control perception) cognitive appraisal. Answers were given based on a 7 point (0 = not at all to 6 = very much) scale.

Finally, the Sport Emotion Questionnaire (SEQ) was used to assess subjective feelings associated with emotions in sport in five dimensions: anxiety, dejection, anger, excitement, and happiness. The instrument consisted of 22 items answered on a five point scale (0 = not at all to 4 = extremely).

Regarding particular stressors, performance and errors were the biggest source of stress, while opponents were the lowest concern. In cognitive appraisal, athletes had a higher tendency to perceive the game more as a challenge than a threat and as having the necessary resources (control perception) to deal with it. Regarding the intensity of emotions, happiness and excitement seemed to be the most prevalent compared to anxiety, dejection, and anger

Regarding the mediation of cognitive appraisal between competitive stressors and emotions, two main aspects should be reinforced. First, higher perception of competitive stressors corresponded to higher experiences of negative emotions; in the same way, higher perception of competitive stressors corresponded to higher threat perception that, in turn, corresponded to less coping perception and lower experiences of positive emotions and higher experiences of negative emotions (confirming the negative pattern of adaptation to competitive stressors).

Conversely, higher challenge perception corresponded to higher control perception and coping perception, higher experiences of positive emotions, and lower experiences of negative emotions (confirming the positive pattern of adaptation to competitive stressors).

P ractical Takeaways

These results confirmed the relationship between competitive stressors and emotions is mediated by the cognitive appraisal, although not all paths in the model were significant. It is also important to note that competitive level assumed a moderating role in these relationships among variables, although the paths are complex to interpret.

Specifically, for U17 athletes, a negative relationship was found between threat perception and perceptions of coping and control, meaning that higher threat predicted less ability to cope and control the competitive stressors related to the upcoming match.

For the U19 athletes, the set of significant relations increased, showing a higher perception of competitive stressors predicted a lower perception of control and a lower perception of coping. Moreover, significant increases in challenge perception predicted higher control perception.

Tom’s C o mme nts Want

“This study highlights the importance of considering cognitive processes in stress adaptation, helping athletes generate challenging evaluations of the sporting events to better cope with them and experience more positive emotions.

“The study emphasises the potential benefits of stress management training with different strategies to cope with stressors, potentially reducing the perception of threat when facing important stressful events. Specifically, goal-setting strategies can help athletes increase control over their performance (shown as a major source of stress), and mental plans and imagery can help athletes deal better with competitive errors (the second major source of stress).

“Athletes can use these strategies before competitions by establishing specific and realistic goals and by defining positive thoughts to use when dealing with significant errors during competitions.

“This study also shows the importance of considering how athletes perceive and cognitively evaluate competitive stressors to understand their emotional experience and how they adapt to a stressful event.

Specifically, it showed athletes who perceive competitive stressors as more challenging (and less threatening) assume more control over the demands and demonstrate to have more resources (coping perception) to deal with them, leading to more positive (and less negative) emotions. Moreover, it was also shown that these effects have stronger or weaker effects based on athletes’ competitive level.”

“This is an interesting study that highlights the areas of concern for this particular set of athletes. It also highlights the requirement for a strategy to cope with these issues and highlights some useful ways to help to improve their mindsets moving forwards.”

D ev e lo ping critical re fle ctio n skills in co ache s

The obvious skills required to coach include a good knowledge of the sport, or what to coach, and a familiarity with how to support learning, or how to coach. Beyond this though we now recognise that critical reflection is an important part of progressing in top-level coaching.

This study considered an intervention aimed at developing the skills of critical reflection with gymnastic coaches to determine the usefulness of a particular type of framework.

Working with the Flemish School for Coach Education, 25 gymnastics coaches (23 females, two males; ages 19 to 40 yrs – average coaching experience = 6.6 ± 4.4 yrs) were split into an intervention group (n = 14) and a control group (n = 11). Their written critical reflection skills were then assessed before and after the intervention.

The intervention took place within a 118-hour coaching period where the intervention group was given an additional course: ‘personal development planning (PDP) for sports coaches’ (aimed at developing critical reflection skills). This included an explanation of the methodologies of reflection, providing analysis tools for facilitating critical reflection, and planning reflection itself This was coupled with one-to-one mentoring sessions.

Before the intervention, all coaches were asked to answer the following questions to assess their critical reflection skills.

1. What are my strengths as a gymnastics coach?

2. What are my areas for improvement as a gymnastics coach?

3. Which values and beliefs are important for me as a gymnastics coach?

4. Where do I want to be as a coach in one year?

5. How do I want my gymnasts to perceive me as a coach?

Their reflections were then judged on a four point scale, from unacceptable to reflective practitioner for

1. Appropriate description of context/experience

2. Clarity

3. Depth of reflection/self-awareness

4. Relevance

5. Personalised authenticity

6. Evidence of criticality

7. Evidence of willingness to reverse/adapt ideas and approaches

8. Planned future actions

P ractical Takeaways

This study suggests that coach education is a good opportunity to improve the skill of coach reflective practice. The researchers hoped that could stimulate use of coach education frameworks to consider the addition of reflective practice, as it is something that is often overlooked or deprioritised in favour of other practices. It is hoped though that this approach can develop the use of this integral skill within the coaching process.

The researchers also consider their specific approach to developing critical reflective skill aids a practitioner’s perception of their ability to reflect, as well as providing more objective data around that skill and increasing their motivation to use the skill.

The intervention had a significant impact on the quality of coaches’ critical reflection. Coaches exhibited a positive, upward trajectory from descriptive verbalisations to a deeper level of self-awareness, and greater criticality, along with demonstrating a willingness to adopt alternative ideas and approaches.

Beyond this, there was also an increase in the amount written by the intervention group when reflecting. This was considered by the researchers to be a positive as they expected it could lead to a more autonomous motivation towards reflective practice itself

“I believe that reflection is a skill that is incredibly important for improving us in whatever discipline we seek to improve at. This study outlines a usable framework that shows good evidence for improving that skill.

“Although the results of this study can only be applied to the cohort used, I think it serves to suggest that coaches, and probably athletes alike, should consider utilising critical reflection in their practice. Beyond this, it should be done in a systematic way and by applying recognised systems when looking to initially integrate its use.”

Tom’s

Te c hno lo gy & M o nito ring

This month ’ s top research on technology and monitori

Inv e stigating the re latio nship betwe e n sle e p, napping and pe rfo rm ance

O BJE C TIV E

For many athletes, a 24-hour day is quickly filled with training, competition, and other responsibilities of life that interfere with the ability to obtain an adequate (7-9-hr) sleep (see HERE).

When sleep duration dips below the recommended 7-hr, mental performance, energy metabolism and hunger cues, as well as the ability to manage inflammation or illness is weakened, ultimately impacting performance potential and increasing the risk of setback.

Due to many athletes training or competing during early mornings or late evenings, a full (>7-hr) night of sleep can be difficult. Therefore, daytime naps are a suggested solution to achieve the recommended amount of sleep the brain and body needs to recover and perform. However, sleep inertia is a window of time following a nap that has been shown to impact cognition and sensory motor activity (see HERE).

There are numerous factors (e.g. nap duration, subsequent task type, time available following) that are not well understood around the potential influence sleep inertia has on performance, and recommendations on how to best manage the effects. Therefore, the purpose of this study was to determine the impact of daytime napping (1- and 2-hr opportunities) on physical and mental performance, as well as subjective self-reports, such as perceived readiness, motivation, and sleepiness.

WHAT THE Y DID

Twelve soccer players (age 18.3 ± 1.0 yrs) who competed in the South Australian National Premier League participated in this study These subjects trained five times per week, played one game each weekend, typically slept eight hours each night, and the majority (n=9) napped four times each week. Each participant was exposed to three conditions (all achieving nine hours of sleep in a 24-hr period) in random order:

Nine-hour sleep opportunity (10pm-7am) but no napping opportunity

§ Eight-hour sleep opportunity (11pm-7am) with a onehour nap opportunity (3-4pm)

§ Seven-hour sleep opportunity (12-7am) with a twohour nap opportunity (2-4pm).

Each subject slept in a private room designed to reduce outside noise, with consistent lighting (~300 lux) during awake hours and temperature (21-23° C). They were provided meals and remained in these rooms with the exception of training and testing.

Sleep metrics (e.g. total sleep time, onset, efficiency and stages (N1-3 and REM)) were gathered using polysomnography (see HERE). Each morning there was a 90-min field-based and gym-based training session with a rating of perceived exertion (RPE) taken following to calculate training load, and free time or nap opportunity in the afternoon in their room.

Starting at 4:15pm, there were four 30-min testing windows that followed the same procedure. First, subjects provided subjective reports based on readiness, motivation, performance prediction, sleepiness, and fatigue. Then a 6-min warm-up was completed, followed by mental and physical performance tests (e.g. 10-m sprint, 90-sec psychomotor vigilance task, 5-0-5 agility test). Finishing the 30-min window with a report of RPE and 5-min of seated rest before repeating the same procedure three more times in the 4:15-6:15pm window

All data (e.g. training load, sleep variables, subjective reports, mental and physical performance results) was analysed for relationship and impact, relative to the napping opportunity (1- or 2-hr window) experienced and the influence and time course of potential sleep inertia.

WHAT THE Y FO U N D

Agility (5-0-5 test) was slower following both nap opportunities (1- and 2-hr).

Reports of sleepiness, readiness, motivation, and performance prediction were negatively impacted following both nap opportunities (1- and 2-hr).

Agility performance, perception of readiness, motivation, and expected performance all improved 60-min after waking up from a nap compared to the reduced values 30-min post-nap.

Neither nap opportunity (1- or 2-hr) impacted sprint performance or mental performance (90-sec psychomotor vigilance task). However, the mental performance test duration may not have been long enough to pick up on reductions in performance and the ability to focus.

Taking a nap (1- or 2-hour duration) did not offer any performance benefit except reduced sleepiness prior to testing activities.

Achieving 9-hr of total sleep, which is the higher end of what is recommended by the National Sleep Foundation for adults, is a good target for athletes aiming to compete and train at a high level through a combination of night-time sleep and naps during the day. However, there was no immediate benefit in taking a 2-hr over a 1-hr nap as long as the 9-hr was achieved.

P ractical Takeaways

Most notably, although subjective reports (e.g. readiness, motivation, expected performance) and agility' performance the 5-0-5 was reduced following a nap, these markers saw improvements after roughly an hour of wakefulness and at least 45-min of warm-up activity prior This encourages two things relative to naps and performance:

§ If an athlete chooses to nap, they should plan to wake up 60-min prior to activity to potentially improve wakefulness and performance in agility tasks.

§ Likewise, a thorough warm-up is critical to increasing psychophysiological function for maximal dynamic effort, improving mental and physical ability

§ This warm-up should allow 5-10 minutes of general activity (walking, jogging, biking) to increase body temperature, following by dynamic movements that achieve full range of motion through muscles and joints that will be used in training, as well as exposure to high-intensity activity (e.g. jumping, sprinting, throwing) to increase neural activation (see HERE).

Athletes who are unable to get the suggested 7-9-hr of sleep per night should consider adding naps into their routine to achieve sleep goals (see HERE) and improve performance (see HERE).

§ Based on the results of this study, a 1-hr nap is sufficient when sleep is 8-hr in the evening. However, there are also recognisable benefits with naps in the 10-20-min length (see HERE).

§ When the window of opportunity for napping is limited, it is best to set an alarm to help the individual from falling into deeper sleep cycles.

§ To improve sleep onset and efficiency, keeping the room dark or wearing a sleep mask can help relax the mind and body by reducing light exposure.

§ Likewise, keeping the room temperature at a consistently cool temperature (15.6-19.4° C) can be helpful for sleep quality (see HERE).

§ Lastly, as to not interfere with the following night's sleep, a nap should not be initiated after 4pm. Coaches should encourage athletes to manage their time and establish a routine that is supportive of their recovery and performance - this reduces fluctuations in mental and physical ability This starts with a consistent bedtime and routine in the evening that involves bathing, relaxed activity (e.g. reading, stretching, meditation), and reducing light exposure from phone and television screens. Doing this helps to maximise the sleep window available and provides consistency in potential in the following day

A final influencer that supports sleep hygiene, subjective reports, and performance is consistent nutrition (e.g. adequate calories and macronutrients) throughout the day. Related to a consistent sleep routine, a routine for meals (e.g. breakfast, lunch, snack, and dinner) allows the necessary opportunities to ensure that calories, hydration, and recovery are further supported for optimal performance.

Want

Cody’s C o mme nts

“A full (9-hr) night’s sleep is likely the most optimal route, especially for afternoon training, but is often unrealistic for athletes who practise or compete late in the evening, or have other responsibilities that squeeze their evening sleep window Therefore, naps offer a way to accumulate the necessary sleep duration that can allow athletes to function at a high level, mentally and physically

“The most important thing to recognise if a napping routine is implemented is to allow roughly an hour from wake-up to the start of training, but to also perform a gradual warm-up that increases core temperature and adequately prepares the brain and body for performance.

“From a sustainability standpoint, a daily nap is often not a realistic piece for many If an athlete becomes reliant on napping, they should reflect on why the nap is needed and look to extend their evening sleep window by getting to bed earlier or trying to sleep a bit later. Coaches can help this process by encouraging evening routine activities that help the mind and body initiate a restful state, as well as limiting early morning training if possible. If early morning training is a consistent aspect to an athlete s day, guidance and structure around proper napping habits are necessary as well.”

D o sing high inte nsity running with a fluctuating m atch sche dule

O BJE C TIV E

A macrocycle represents a full training cycle, typically including an in- and off-season period. A mesocycle represents a series of weeks (typically 2-6) that has a specific focus (e.g. training target or competition period). Zooming in further, a microcycle represents roughly a week’s worth of training (anywhere from 4-10 days) that appropriately balances stress and recovery to support the mesocycle and macrocycle goals.

Generalisations can be made for each segment of time, but as a coach continues to zoom in on the days of training, there are considerations in how to arrange each week based on accomplishing the training prescription necessary to optimise performance.

Especially during the in-season period, there are discrepancies in how coaches plan a microcycleallowing recovery from a previous match, while at least maintaining performance potential for subsequent matches. Simultaneously, it is rare that two weeks are alike, due to fluctuations in schedules, combined with uncertainty around best practice for high-speed running exposure to prepare for competition demands. While this holds true for all sports, for soccer specifically, highspeed efforts have increased by 30-50% in recent years (see ). Balancing this necessary but highly stressful HERE locomotive activity is critical for performance and injury mitigation (see HERE).

Therefore, this research examined the distribution of various high-speed running intensities across a microcycle, with respect to how the volume of work was allocated in the days prior to a match, as well as considering the number of available training days in the week based on match schedule.

WHAT THE Y DID WHAT THE Y FO U N D

A Spanish first division (La Liga) team of 23 soccer players (age 27 ± 3.5-yr) were monitored daily during the 2018-19 competitive season using 10 Hz global positioning system (GPS) units (S5, Catapult Innovations) on a daily basis during training activities. The specific external variables examined from the GPS devices during training calculated high-intensity running distances and occurrence (frequency) at three levels: high-speed running (HSR, >21-km∙h-1), very high-speed running VHSR, >24- km∙h-1), and sprinting (SPR, >27- km∙h-1).

A total of 28 weeks of data was analysed based on specific criteria: only considering sessions where all players trained together, where each week there was only one official match and at least four training sessions. All data was analysed based on the number of days prior to a match (i.e., from 1-7 days prior), as well as the number of training days in the microcycle (i.e., 4-7 days), not including the competition itself for comparison. These variables were compared to determine trends related to high-speed running intensity as it related to microcycle arrangement (e.g. day prior to match and available training days.

A longer microcycle (more training days between matches) did not result in an increase in highintensity running (HSR, VHSR, and SPR) distance. Generally, the greatest distance and occurrence of high-intensity running occurred 3-5 days prior to a match. Specifically, though, when the microcycle involved seven training days, 4-5 days out from the match had higher high-intensity running values than the shorter (4-5 day) microcycles.

Given the variance in microcycle length, there was not a consistent allocation of high-intensity running activity on specific days relative to the upcoming match.

Although efforts were made to reduce variance, the standard deviations between average distances and occurrences for each data set (HSR, VHSR, and SPR) was substantial, swinging as much as ±60% for some variables (SPR distance (30.5±18 m) in a fiveday microcycle). This suggested substantial disparity between players.

P ractical Takeaways

High-intensity running in training is critical to performance and reducing injury risk (see HERE), but the timing of higher volumes of this work needs to be strategic. The most stressful training sessions should occur in the middle of the microcycle between matches, allowing time (1-2 days) to recover from the previous match, as well as time to recover (1-2 days) prior to the subsequent match. Not to mention, there is evidence to suggest that sprinting activities in the 72 hours prior to a match can improve heart rate response to imposed competition demands (e.g. training impulse) (see HERE)

§ An observation of this research worth noting is that all types of running (HSR, VHSR, and SPR) occurred on all training days of the microcycle. This suggested at least a high frequency micro-dosing of exposure for performance maintenance and injury mitigation to the locomotive stressor, which would be preparatory and beneficial for condensed tournament play late in the season.

§ Coaches should also appreciate that a training session can still be productive without high-intensity running activities. Especially for the training sessions in the days (n=1-2) before and after a match, highintensity work can be minimal and the focus can be technical (e.g. ball handling, passing, shooting) or tactical (e.g. film study or walk through of offensive attacks and defensive strategies), with a lower intensity aerobic benefit to the training activity (more jogging, walking, instruction, and discussion). This sort of session can culminate with a guided stretch for increased blood flow, relaxation, and potentially increased recovery benefits.

Coaches should emphasise rest and recovery during stretches of the season when able (e.g. extended 6-7 day gaps between matches), as opposed to adding more stress and load to recover from. First, consider the overall preparedness and technical and tactical proficiency of the team to determine the amount of work that needs to be accomplished between matches, with an emphasis on preparation for the upcoming match and promoting longevity through the remainder of the season. If deemed necessary, perform the most intense session earlier in the week (e.g. 4-5 days prior to the upcoming match). Use that extended window as an opportunity to reduce accumulated in-season fatigue by managing workload judiciously § An example of this from the study that is worth noting - there were no training sessions held the day prior to a match when the microcycle was a full seven days and an increase in high-intensity running distance did not occur with more training opportunities between matches.

Coaches must remember to be flexible in their original plan and desired volume of work, especially as days between competitions fluctuate. Coaches should not be overly strict with any of the FITT-VP variables (frequency, intensity, time, type, volume and progression of training). Rather, to help identify readiness, lean on subjective (e.g. reports of soreness, fatigue, or exertion) or objective monitoring strategies (e.g. heart rate variability, total distance covered, minutes played). Likewise, an objective measurement of performance (e.g. top speed achieved, 10-m sprint time) can help determine opportunities to accomplish higher volumes of quality high-intensity work. These strategies can provide potential suggestions on increasing or decreasing planned loads for the day (e.g. if subjective reports are poor, coaches may consider reducing volume or intensity of work by decreasing the size of playing field, increasing rest periods, or decreasing the duration of practice).

Generally, in-season training sessions should not exceed the volume or intensity of a competition, as that is arguably too much stress to recover from, overstressing the athlete and team. This is especially true for a player contributing significant and consistent match-minutes. A variance is expected and appropriate, based on the position, performance status (e.g. fitness level), and match-load each individual is experiencing (e.g. minutes played or distances covered during competition).

§ Much of the volume of high-intensity running can be accomplished concurrently during drills or smallsided games, but for players who do not play much in the match, and need to accumulate more workload at higher speeds, they may be prescribed specific running (distances and speeds) to accumulate necessary workload to maintain performance and be ready to perform at their maximal potential if called upon.

Coaches should adapt their microcycle training philosophy to the squad, considering the number of players that contribute consistently, the length of the season, and the physical capacities of the players themselves. Much of the ‘work’ is done during the off- and pre-season periods, whereas the primary focus of the in-season period should centre on recovery and player availability This means training sessions are about doing as little as needed versus as much as possible. Focus on doing enough but be cautious of doing too much.

§ One consideration that seemed to work well for the team in this study was having the lightest (lowest volume of high-intensity running) session two days prior to the match. There could have been multiple reasons for this decision but leaning on the athletes for their preference is a possible way to help decide, and having the monitoring data to back it up reinforces accomplishing the intended training volumes. For most external training load data collected, it should not come as a surprise to the coaching staff, but merely reinforce what was intended based on readiness and the number of days prior to a match.

Cody’s C o mme nts

“Ultimately what matters most is that players feel ready to perform at their very best on gameday. In order to maintain performance across a lengthy season, this requires a constant balancing act of stress and recovery across the week. The training is necessary because the season is so long and if qualities are not properly maintained, players can be put at risk of injury. It is important to respect the demands of competition and remain focused on player availability.”

“When available, coaches need to use data to their advantage, applying it to support their decisions and improve confidence in their preparation. For programs with limited resources, this may be very simple such as manipulating total duration (minutes) or simply reps of a high-intensity drill, followed by a subjective rating of perceived exertion following training. Regardless of the monitoring strategy inseason, the priority is match-day readiness. This research is a good reminder to have a general pattern, but to also be adaptable to the individual and context of the week.”

A n ov e rv iew of using he art rate variability to guide training

O BJE C TIV E

Heart rate variability (HRV) is a monitoring metric that analyses the variance between heart beats (see HERE), and has become a widely used and potential method of tracking an athlete’s response to training, their environment, and the recovery process (see HERE).

HRV has been heavily researched since the early 1970s (see ) and can serve as an objective measure of an HERE athlete’s physiological readiness, representing a complex interaction of an individual’s autonomic system input (sympathetic (SNS) and parasympathetic nervous system (PNS) fluctuation), respiration, and blood pressure. These are all functional systems that change under high levels of training intensity and volume.

Especially as it relates to endurance athletes, HRV was first explored in the 1990s (see ) and in recent years, HERE advancements in technology have made the accessibility of this measure better than ever The problem however exists in the consistency and reliability of these measures, the analysis of the data, how it is collected, compared, and integrated to make decisions around the direction or prescription of training load.

Therefore, the goal of this review paper was to provide an explanation for why and how a coach or athlete would consider utilising a HRV measurement as a monitoring strategy for endurance athletes. There are three key areas highlighted for consideration: providing valid and actionable data, primary influences that modulate an athlete’s HRV and how it can direct daily training prescription, and discussion around potential directions that HRV monitoring could expand to in the future.

WHAT THE Y DID

The authors outlined what HRV can potentially showcase from a physiological standpoint as it relates to an athlete in training - specifically, the application of HRV as a marker for performance and monitoring readiness. The authors covered the various analysis techniques used to calculate HRV (via time, frequency, and nonlinear domains, see ), highlighting what methods are most HERE popular, reliable, and sensitive from years of research. Likewise, the various measurement tool options (electrocardiogram, smartphone photoplethysmography (PPG, see ), heart rate chest strap, watch, or ring) HERE were discussed. Testing procedure considerations for reliable measurements were also summarised.

From there, the authors explained how various training volume, intensity, mode, and even lifestyle factors can influence resting HRV results, with recommendations based upon guiding training and how HRV can be used to identify maladaptive states.

Finally, non-traditional methods and potential ‘future directions’ (e.g. measuring HRV during exercise, immediate post-exercise HRV measurements) were presented. The authors thoroughly overview HRV as an opportunity for actionable insight into the physiological changes an athlete experiences throughout training.

Ultimately, there is a plethora of research that is covered to support the use of daily HRV monitoring, but the review also recognises that it is merely one measure in a complex environment of athletic performance.

Of the ‘time domain’ HRV measures, standard deviation of the normal-normal intervals and the root mean square of the successive differences (RMSSD) are the two most typically used (see HERE). RMSSD provided the best representation of PNS activity (see ) due to reflection of short- HERE term variability, withstanding changes in respiration, and low typical error (see HERE).

An electrocardiography is the criterion measure of HRV but use with a chest strap has proven to be reliable (see ). There is recent support for HERE measurements via PPG, using a watch or smarthphone camera that allows for convenient and consistent HRV measurement (see HERE).

From a practicality standpoint, a one-minute HRV measurement is likely the shortest recommended before reliability is lost when compared to suggested 5- or 30-min measurements (see HERE), as 10- or 30-sec measurements are significantly different (see HERE).

An athlete’s HRV is typically reduced following work above the first ventilatory threshold (Vt1), irrespective of volume (see ), However, HRV HERE response to high-intensity or volume hinges heavily on the fitness capacity (trained or untrained, see HERE), finding those who are well trained are more resilient and return to baseline faster following increased training loads.

Training that is ‘HRV-guided’ (adjusted based on measurements) has shown great promise by reducing the total amount of work, taking advantage of the adaptability of an athlete on a given day, and providing a sometimes-greater training effect when compared to a predetermined training plan (see and HERE, HERE, HERE, HERE).

Measuring HRV during exercise appears to be impractical, inaccurate at high intensity, and uninformative regarding training direction.

P ractical Takeaways

With endurance athletes, HRV measurements can be used as a marker of performance over time. Upward trends (increases) over months of training in HRV for endurance athletes is suggestive of increased aerobic capacity and improved 10-km run performance (see HERE). Therefore, consistently measuring (>3 times per week) is important to provide the athlete with feedback and confidence related to physiological changes.

When testing, consistency in measurement procedure is essential (e.g. stable condition (no movement), consistently positioned (seated, supine, or standing), maintaining a natural breathing rhythm). HRV metrics are highest while lying supine, but research has found that seated measures are able to be more reflective of fitness changes (see HERE).

A one-minute test performed at the same time each day (e.g. immediately after waking) helps to provide consistent and comparable data without distraction or interruption. Overnight readings are also an option (see ), but that may carry a considerable amount of movement that HERE impacts the data, or the window of sleep may be different due to competition, travel, or training. Therefore, the one-minute measure upon waking is likely the most useful method.

An HRV measurement is individual (based on training load, fitness level, age, sex, stress, lifestyle, etc.) - it should not be compared with another as good or bad, but simply referenced against previous readings for that individual to help infer response to training, life, and provide suggestions in prescription moving forward. This is why it is important to commit to consistently measuring at least three days a week to gain understanding of how an athlete responds to training across the micro-, meso-, and macrocycle, as having that insight can help coaches appreciate the highs and lows of a year and how it relates to training.

A baseline HRV can be established in a matter of days (see ), and then using smallest HERE worthwhile change (see ) to alert coaches of potential concerns that would necessitate HERE reducing or changing training prescription.

A reduced HRV reading compared to previous (or below the general norm) is expected following heavy training (see ), which has also shown to be indicative of decreased HERE performance potential (see ). Repeated reduced HRV readings should be avoided without HERE accompanied training modifications, as this can be indicative of overtraining syndrome (see HERE).

Pairing an HRV reading with a subjective report of readiness via a questionnaire (see ) can HERE help to provide coaches with more context and confidence in recognising a ‘ready-to-go’ or ‘fatigued’ athlete who may need training modifications.

Incorporating HRV monitoring for an athlete can serve as a means of monitoring lifestyle and recovery habits (e.g. stress management, anxiety, depression nutrition, alcohol consumption, smoking, sleep, body composition), as all of these can influence resting HRV on a daily basis (see ). Therefore, an HRV measurement can serve as an accountability piece or HERE conversation starter to understand further how an athlete thinks and operates off the field or outside of training.

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Cody’s C o mme nts

“Implementing HRV for an athlete is a step that recognises the appreciation necessary for viewing the athlete as an adaptive and dynamic organism - one that is influenced by training, environment, nutrition, sleep, recovery, stress, relationships, and genetics to name a few.”

“HRV is influenced by numerous functional systems (e.g. autonomic, cardiovascular, respiratory, central, etc). Therefore, HRV has shown robust validity as an objective measurement and quantified representation of an athlete’s physiological state relative to the response to all the influences listed above.”

“This is often neglected due to an athlete s complex physiology, but it appears to be a simple yet productive measurement. It can help direct the day’s prescription and the athlete s ability to adapt to the stresses that are being imposed through training and their environment.”

“Given the volume of research favouring ‘HRV-guided’ training compared to predetermined training, the value of HRV as a monitoring tool has strong support. It was consistently found that when using HRV to guide prescription, training was either more beneficial or less invasive (overall less load) than when following a predetermined plan.”

“When measured correctly, HRV is a valid, reliable, and insightful measurement for coaches who are humble enough to divert from the plan and use the feedback to their advantage.”

A tim e e fficie nt and e ffe ctiv e m o dificatio n to the iso m etric m id- thigh pull assessme nt

O BJE C TIV E

Laboratory use of force plates, and measurements of force production capacity, have made their way into the sport performance monitoring scene in recent years; now force plates are finding a home amongst the barbells, dumbbells, and squat racks that athletes use to strength train.

Many coaches use either an isometric squat or isometric mid-thigh pull (IMTP) to assess a systemic ability to generate peak force, and at high sampling rates (100-Hz), assess the force-time characteristics in a matter of milliseconds (ms, e.g. rate of force development (RFD) at 90-ms). With this information, coaches can pay attention to the explosive actions that are necessary to maximise sport performance (see ), and monitor readiness HERE through changes in neuromuscular function (see HERE). Likewise, identifying an assessment tool that is time- and energy-efficient for athletes is important for coaches managing busy in-season schedules, especially for larger teams of 20+ athletes.

Although a one-second isometric squat test has shown promise for obtaining valid and reliable RFD measurements (see ), it is unclear if the same holds HERE true for a time-restricted IMTP and how that relates to more generalised sport performance (e.g. jumping or sprinting ability). Therefore, this research compared a 1sec IMTP with a traditional (no time limit, TRAD) IMTP measure, specifically examining intra- and inter-session reliability for each, as well as comparing the performance data as it relates to vertical jump capacity

WHAT THE Y DID

Thirteen men (age 26.8±5-yr) participated in this comparison of IMTP protocols using dual force plates with a sampling rate of 1000-Hz. Each participant came into the research lab three separate times - the first session was for onboarding and familiarisation with the protocols, the second was the day after for initial testing, and the third session was a week following the initial session for a repeat of testing.

Bar height was selected by keeping the torso vertical, and knee angle at 120-130° (a position that allows for highest force production potential, see ). Warm-up HERE remained consistent, with opportunity to build the intensity of efforts preceding the official measurements. Lifting straps and tape were allowed to eliminate grip strength as a limitation, and instructions around creating tension prior and encouragement to “pull as fast and hard as possible” after a 3-sec countdown remained consistent for each trial. The first IMTP protocol was limited to 1-sec in duration, while the other TRAD protocol lasted until there was a stabilisation in force production or a decrease began to occur

The 1-sec IMTP protocol was performed first, with 30-sec rest between two maximal efforts. This was followed by 3-min of rest before performing two attempts of the TRAD IMTP protocol, with 2-min rest between the maximal efforts. Lastly, two versions of squat jumps (loaded and unloaded), measuring vertical jump performance were completed. Each jump began from an isometric 90° knee angle, the loaded jump involved a 20kg bar across the shoulders, while the unloaded measure involved holding a lightweight dowel (pvc pipe) across the shoulders. One minute of rest was given for two maximal reps of each squat jump version.

For both IMTP measures and jumps heights, averages were taken for the best two values from each protocol. When analysing the force-time curves of the IMTP protocols, researchers examined peak force values, as well as force values at 90- and 200-ms to calculate RFDt (change in force/change in time) and impulse (force x time). These time points coincide with what is considered ‘early’ and ‘late force-time measures relative to different mechanisms contributing to the performance (see HERE).

Researchers examined the relationship between measures and each IMTP protocol, looked for a comparison to jump performance, as well as intra- and inter-session reliability of each IMTP protocol.

WHAT THE Y FO U N D

The 1-sec IMTP protocol had similar peak force values when compared to the TRAD IMTP

However, the early force-time performance of the 1-sec IMTP was much greater than the TRAD IMTP

Interestingly, the 30-sec rest periods given for the 1sec IMTP value seemingly did not interfere with performance, since peak force values were similar and rate of force production was greater than TRAD IMTP

Rate of force development at 90-ms for the TRAD IMTP was the only measure that was correlated with either squat jump (loaded or unloaded). No other measure from either IMTP protocol was indicative of jumping ability

Peak measures were reliable intra- and intersession for both IMTP protocols (1-sec and TRAD).

However, RFD measures intra-session were more reliable for the 1-sec protocol, but comparable inter-session for both protocols.

P ractical Takeaways

Coaches can promote greater levels of intention with their athletes’ efforts during an IMTP by placing a time restriction on the effort.

§ This is especially consistent with the high rate of force and impulse demanded from nearly every sport involving quick reaction, high acceleration, and power production. The ability to produce peak force rapidly is supportive and influential to performance across all sports.

Even more impressive is that only allowing 1-sec to achieve peak force was not a limitation to what these athletes were ultimately capable of. Placing the time demand on the IMTP protocol still allowed for coaches to measure peak force capacity in these athletes, which is a usable measure of improvements from strength training.

Most notably, the 1-sec IMTP protocol was much more time efficient and less fatiguing for athletes. Only a 30-sec rest period was required, and the time restriction reduced the extensive strain of effort to achieve a maximal force output. Given the results, this was effort wasted and time saved by reducing the protocol s time and rest.

§ By selecting this modified IMTP method, there is opportunity for more frequent testing (e.g. weekly) since it is less fatiguing, making it a more practical and repeatable option for monitoring performance.

§ This test could be performed after a warm-up prior to a lifting session to help guide intensity and volume of the session. If performance is stable or improved, it provides confidence in the athlete s efforts and ability to train at a high-intensity for the session. Alternatively, if performance is significantly reduced, it may be a sign the athlete needs to reduce volume and/or intensity for the session and allow for recovery

§ All in all, this 1-sec IMTP test can help increase the energy and enthusiasm around a team’s weight room session, holding athletes accountable to their efforts, encouraging competition, and boosting morale with positive results.

When implementing an IMTP protocol, it is important to keep instructions concise and consistent (e.g. “pull as fast and as hard as possible”). It is critical athletes understand the purpose and execution of the assessment.

An unexpected finding was the lack of relationship between the 1-sec IMTP and jump performance, but that goes to show the specificity of the test and especially the experience of the participants (e.g. weightlifters). When selecting assessments, be sure to use ones that show transfer to performance that matters on the field.

§ Likewise, be sure to explain to the athletes that this is merely an opportunity to showcase performance - it is not a pass/fail test. Framing the assessment in a manner that is encouraging can bode well for favourable efforts and results. In the end, it’s a repeatable test they will continue to improve upon through familiarisation.

If force plates are not available, there are opportunities with load cells (e.g. crane scales) from a hardware store that are used in weighing and measuring various things such as luggage that can be used with a chain and bar affixed to the floor as an alternative measure that is much more cost effective. You may lose out on some of the force-time characteristics but only allowing 1-sec will allow a burst of effort to measure peak force outputs in an athlete.

These results further support the 1-sec protocol that was found to have reliable RFD values using an isometric squat as well (see ), which could serve as an alternative for a team not concerned with HERE grip and systemic strength, but rather focusing solely on lower body by using a belt squat set-up. This may serve running sports (e.g. soccer, track and field) better than the TRAD IMTP considering that RFD at 90-ms was the only measure to relate to jumping ability, and jumping is strongly related to sprinting performance (see HERE).

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Cody’s C o mme nts

“This research is an excellent example of adapting an assessment that otherwise would only be performed occasionally, into one that can be performed more frequently. It provides a less taxing method and arguably better return on efforts from a force-time curve perspective. Ultimately, providing a more repeatable and reliable data from a 1-sec IMTP protocol. This time restriction provides the best return on efforts of both the coaches, and more importantly, the athletes because it is saving both time and mitigating fatigue.

“These are principles that should be employed by coaches when selecting monitoring or assessment measurements - identifying ones that flow with the training process, do not create anxiety, risk of injury, and are time efficient. The worst thing a monitoring or assessment strategy can do is to bring additional stress demands on an athlete and employ a method that takes away from the training and preparation for the next competition. The 1-sec IMTP test is a seemingly great option to be used weekly throughout the season.”

Fatigue & Re cove ry

W hat is the be st way to track fatigue afte r re sistance exe rcise?

Resistance training has long-term positive effects and is a proven way to improve physical fitness, muscle strength and power A training session performed with high intensity or excess overload stress can lead to damage in the muscle and rise in blood markers, which can elicit an inflammatory response lasting for several hours or days. This can lead to prolonged soreness and an overall decrease in muscle function.

As a result, the knowledge of a proper way to track fatigue markers following resistance training is vital in order for the individualisation of recovery time between sessions. The purpose of this article was to investigate how to identify the markers over time of muscle fatigue after a strenuous lower extremity resistance exercise program.

Sixteen healthy men aged between 18 and 26 participated in the study; they all had about five years of experience with resistance training and had a 1RM of 147 ± 33 kg for a back squat.

The participants had their 1RM measured in the first session along with anthropometric measures. A week later, measures of neuromuscular performance tests, heart rate variability and the Perceptual Recovery Scale (PRS) were administered, followed by the resistance exercise program. This consisted of eight sets of 10 repetitions of a back squat with 70% of their 1RM with two minutes of rest in between sets.

The following markers were measured again at 24, 48 and 72 hours post resistance training program:

§ Countermovement jump

§ Bar velocity

§ Isometric mid-thigh pull

§ Step counts

§ Heart rate variability

§ Subjective assessment via the Perceptual Recovery Scale

In the study, the authors characterised muscle fatigue by a reduction in CMJ performance, which occurred at 24 and 48 hours post session.

The PRS scores showed the greatest sensitivity for the tracking of muscular fatigue as defined by the authors after an acute session of resistance exercise, as it showed consistent reduction at all moments tracked (24, 48 and 72 hours).

The following results were found for the other measures tested in this study:

§ Bar velocity showed significant reduction but only at the 72-hour mark.

§ Isometric midthigh pull mean force decreased at 24 hours but peak force decreased only at 48 hours.

§ HRV and step count showed no significant changes from baseline.

Practical Takeaways

Tracking muscular fatigue is essential for athletes who participate in resistance training. Avoiding excessive overload and stress to the muscles allows athletes to make positive strength gains, whether in-season or just to continue healthy habits. The use of a countermovement jump to track this fatigue has merit, based on the findings in this study

The subjective assessment of the participants’ perceived recovery from the program showed consistent decreases from baseline measures. Athletes and the general population would benefit from using this type of assessment as they continue training efforts.

The measurement of the mid-thigh pull for this type of study may have been flawed due to it testing isometric strength. This type of contraction is influenced less by muscle inflammation and alterations in joint mechanics that are generated with most lower extremity resistance exercises.

Heart rate variability was not sensitive for tracking over multiple days and may be of better use when tracked over several hours, as in other studies.

Step count did not significantly change. This may have been influenced by daily activities and movements that the athletes’ took part in. This measure may have produced different results if the type of lower body movement was different or if upper extremity exercises were utilised.

“Resistance exercise is essential for training programs but must be tracked properly in order to avoid over-stressing the muscles involved. Understanding their own perceived recovery may assist athletes and people who consistently exercise to recover more efficiently and produce gains in strength.”

“Countermovement jump decreases occur after an exercise program consisting of repetitions of squat patterns. Avoiding this type of movement along with other high intensity / dynamic closed kinetic chain movements on consecutive days in a training program may be beneficial to avoid overtraining.”

“Although this study showed positive correlations and results, it was limited by the participants studied. It would be also interesting to look at these markers with an untrained population or female population. Along with this, the use of upper extremity exercise may produce different results.”

H ow do m uscle s re spo nd to diffe re nt ty pe s of re sistance training exe rcises?

Changes in the variables associated with resistance training may induce different responses when comparing muscle soreness (MS), limb circumference (LC) and muscle thickness (MT). These changes may also produce differences in maximal strength and activation of the muscles involved.

Multiple joint exercises (MULTI) have been viewed to be more effective for inducing metabolic stress along with mimicking daily tasks and sport specific movements. On the other hand, single joint exercises (SINGLE) require lower technical demand and have been thought to be beneficial for targeting specific muscles while correcting imbalances.

The purpose of this study was to compare the differences in MS, LC and MT in a back squat (MULTI) and a knee extension (SINGLE) exercise.

Ten males aged between 19-34 yrs, who participated in resistance training at least three days per week for two to five years on average and were free of injury, participated. They were split into two groups: knee extension or back squat.

1 RM and 8 RM were measured for both exercises along with assessment of health via the Physical Activity Readiness Questionnaire (PAR-Q).

Prior to completing the exercise protocol, there were baseline measurements for the following:

Muscle thickness via ultrasound. This was characterised as muscle swelling.

Limb circumference on the right rectus femoris

Muscle soreness via a Visual Analog Scale from 0-10 (0 being no soreness and 10 being extreme soreness)

Overall wellbeing, which was a scale assessing subject’s fatigue, sleep quality, general muscle soreness and stress levels on a five point scale

Participants performed the maximal repetitions that they could manage until failure for the study protocol. Their loads were 8RM for five sets, performed at four seconds per repetition. Participants completed the exercise protocol for their respective exercise twice, with 96 hours of rest between.

Practical Takeaways

When comparing these two exercises, back squats produce more changes in the muscle when compared to a knee extension exercise. This was measured via changes in the quadriceps. The multi joint exercise most likely produced more damage due to the elevated metabolic demand that is induced from the increase in contributing muscles like the hamstrings and gluteals. This could consequently have a greater influence on the level of fatigue experienced by the participants.

With the increase in muscle damage experienced by the multi joint exercise, a single joint exercise may be more beneficial for an in-season athlete who is either dealing with or trying to prevent injury A compound activity however, can be beneficial as well when done with correct form and dosed appropriately to avoid injury

These training results can influence the way that coaches and rehabilitation professionals prescribe exercise depending on the goals of the client.

Limitations in this study are present and include the fact that no direct assessment of muscle damage was adopted along with a limited sample size and use of only two exercises.

Muscle soreness was elevated with both exercises from baseline to 36 hours post-exercise. The muscle soreness was measured as higher in the back squat exercise when compared to the knee extension at both 24 and 36 hours post exercise.

For leg circumference, increases were found with both exercises at all measured times. The back squat however, produced greater changes immediately following the exercises. Muscle thickness was elevated at all times measured but was also highest in the body squat compared with the knee extension immediately and 36 hours after the exercise.

There was no significant difference found with the wellness scores. Based on these findings, it was concluded that multi joint exercises produce more muscle damage when compared to single joint exercises.

“This study provides beneficial information on the muscle damage that may occur from multi joint and single joint exercises. It would be interesting to compare these results when looking at a single joint exercise targeted toward the hamstrings, glutes or calf musculature in place of the quadricep”.

“Rehabilitation professionals and coaches need to understand the important differences between multi joint and single joint exercises and prescribe their programs based on an individual's needs. A client may need to have a program focused on single joint rather than multi, when less fatigue and a faster recovery is desired.”

T he e ffe cts of small side d so cce r gam e s o n pe rfo rm ance and re cov e ry

Small-Sided Soccer Games (SSG) are played with fewer players on a smaller pitch than traditional matches and are utilised to improve tactical and physical performance. This type of training forces players to accelerate and decelerate more due to the fast pace being played in a smaller area. This induces high intensity aerobic and anaerobic output which impacts heart rate as well as other biochemical and hormonal markers. Among those that may be affected include creatine kinase (CK), interleukin-6, testosterone and cortisol levels, which are vital for recovery and performance.

The present study examined the effect that SSG had on those markers as well as jump and sprint performance. The purpose was to determine the appropriate time needed for recovery for the soccer players so injury and overtraining risk were reduced.

Twenty-two male players from the 3rd division of the Greek National Soccer League were included in the study. Players included were male, non-smokers, slept more than seven hours per night and had no current injury

There were two groups in this study; an experimental group consisting of 12 players and a control group consisting of 10 players. In order to make the SSG teams, the experimental group was split into four groups of three. The control group did not participate in playing.

Both groups had an introduction session, which included measurement of body mass, height and body fat percentage. This was followed by determination of heart rate (HR) max via the Yo-Yo Intermittent Recovery Test Level 1.

The experimental session was performed five days following the introduction. Players in the experimental group played a 3 vs. 3, 45-minute SSG consisting of eight three-minute sessions, with three minutes of active recovery in between. This was designed by the researchers in order to simulate a soccer match. The following markers were measured:

§ HR was measured every five seconds via short-range radio telemetry

§ Subjective rating of perceived exertion (RPE) was recorded at rest prior to the SSG and then at the end of the second, fifth, and eighth set, along with 24, 48 and 72 hours post SSG.

§ Blood lactate was measured via a portable blood analyzer. It was measured prior to the SSG and one minute after the second and fifth set, and 8-10 minutes after the end of the eighth set of the SSG.

§ Squat jump (SJ) testing was performed 45 minutes prior to the SSG. Three maximum squat jumps with an arm swing and 30 seconds between jumps was measured via a customised uniaxial force plate. The jump test was repeated 15 minutes and 24, 48 and 72 hours post SSG. The best of the three squat jumps at each interval was used for analysis.

§ Sprint testing (20m sprints with a 30-second recovery between) was performed five minutes after each SJ, with the best sprint time being used for analysis.

§ Hematological measurement was performed via 10ml of blood collection 1.5 hours prior to the SSG, immediately after and 24, 48 and 72 hours after the SSG.

Practical Takeaways

As noted above, inflammatory responses peaked following completion of the game but returned to rest values within 24 hours. With this information, we can conclude that a 48-hour period at most following SSG training sessions seems to be adequate time for players to recover This is useful for designing training programs for players and teams.

Jumping and sprint measurements do not seem to be affected by SSG training sessions. With this information, coaches can implement power training sessions the day following SSG with less concern of risk of increase in muscle damage assuming other training load markers are being met.

From this information, high load cardiovascular aerobic/anaerobic training should be avoided within the first 24 hours following SSG to avoid overtraining and muscle damage.

This study looked at a semi-professional athletic population and did not account for amateur or female athletes. Data on the inflammatory markers along with performance in sprinting and power may have been different in these subgroups. Along with this, the timing of the study may have affected results as it was performed at the end of the season. How would this change if the SSG testing was performed during the season or in the pre-season, when endurance levels may have been different?

There were no significant differences between groups prior to the SSG. HR, during the experimental session, reached an average of 168 ± 7 bpm corresponding to a 87 ± 4% HRmax. The HRmax increased as the SSG progressed in time. Along with this, blood lactate levels and reported RPE reached levels that are observed while in anaerobic training. For hormonal and biochemical markers, the following were found:

§ Interleukin-6 showed a significant difference and peaked immediately after the SSG, while returning to baseline at 72 hours post SSG.

§ CK responses showed a significant difference and peaked 24 hours after the SSG and remained that way 48 and 72 hours after the SSG.

§ Cortisol responses showed a significant difference and peaked immediately after the SSG and remained that way for 24 hours, but returned to baseline at 48-72 hours post SSG.

§ Testosterone responses showed a significant difference and peaked immediately after the SSG and returned to baseline 24 hours later

§ Testosterone to Cortisol (T/C) ratio was lowest immediately after the SSG and returned to baseline the next morning.

§ Squat jumping and sprint measurements did not show statistically significant differences in the experimental group.

“SSGs are a useful tool in order to reach high levels of aerobic and anaerobic training. It should be utilised in order to improve players’ skill sets along with training endurance. Coaches must be careful to give ample recovery between sessions in order to avoid overtraining and muscle damage. Other training, focusing on power and strength, may be useful in between sessions.

“Repetitive bouts of SSG with appropriate time in between can be useful in order to improve endurance in elite soccer players. Tactical skill can also be improved as the goal of the training is to keep possession. This can be useful for skill coaches to use with players throughout the season.

“As a rehabilitation professional, I believe SSGs are a great way to reach high levels of anaerobic training and induce positive changes in performance measures as long as proper recovery time is given. Although the current study looked at soccer, this information may be valuable for other activities including basketball and tennis.”

Yo uth D eve lo pm e nt

This month ’ s top research on youth development.

W hich training methods are most for young soccer play ers? A compa multiple approaches

W hich training m etho ds are m o st e ffe ctiv e fo r yo ung so cce r play e rs?

co m pariso n of m ultiple appro ache s

When working with youth, there is often a limited time window which exists to develop multiple fitness qualities such as strength, speed, change of direction (COD) and jump performance in adolescent soccer players. Creating a plan which balances out all of these qualities (i.e. strength and speed) adequately, which are essential for the short, intermittent nature of soccer, is challenging for well-trained athletes and coaches.

To the authors’ knowledge, few studies have investigated the impact of developing multiple-fitness qualities in youth. Therefore, the aim of this study was to observe the benefits of plyometric and sprint training, functional training, and strength training on elite adolescent soccer players which can be advantageous to performance.

Forty-eight elite adolescent athletes (17-18yrs) from four top German clubs were recruited for this study The athletes were considered well-trained, as they completed 4-5 regular training sessions per-week.

To ensure the participants were familiar with the testing protocol, a 10-month intervention period was selected and undertaken in this study. Prior to being placed into one of four intervention groups, all participants completed a 20m sprint, a COD triangle test with (HERE) both a left and right turn, a squat jump and a onerepetition maximum squat test for pre vs. post measures. The four training interventions were as follows.

1. Strength training intervention – that engaged in compound patterns (i.e. squat and deadlift) at 3 sets of 10 repetitions.

2. A plyometric and sprint training group – which completed vertical and horizontal jump training coupled with resisted sprints at 80-100% intensity

3. A functional training group – which completed a series of exercises that incorporated concepts such as balance, core, bodyweight, and elastic band training in a progressive manner

4. A control group – which completed regular soccer training with no additional interventions. These sessions were completed twice weekly and lasted roughly 60 minutes.

Practical Takeaways

In this study, strength training was shown as the most effective method over a 10-month period when working with youth. In the programme, the exercises included were squats, deadlifts, bench press, pull-ups and sit-ups. Whilst these are fantastic exercises and should form the basis of any good strength programme, coaches may also wish to investigate a needs analysis of soccer (see attached article). This would reveal that common injuries in soccer occur at the hamstring, knee and ankle.

To combat this, I would personally look to include some single-leg variation work (i.e. Romanian deadlifts, glute bridges, and single-leg squats), eccentric hamstring strength work (e.g. bilateral Romanian deadlifts and Nordic Hamstring exercise) and some ankle capacity work, such as the ALTIS rudiment series This provides (HERE). enough variation to avoid programme tedium, but could also be used as a useful tool for screening. Although this study found little improvement when following a plyometric and sprint intervention, sprinting is the biggest contributor to developing speed and reducing hamstring injury, so in my opinion, all youth should be sprinting once or twice a week. If you don’t know how much sprint training is required, a good number to aim for is five repetitions across 30-40m at 100% intensity within a week.

Finally, functional training showed little to no improvement in all measured qualities. However, it is my opinion that mini-band work, foam rolling, Russian twist and TRX work can serve as valuable additions to a programme, as long as they aren’t the primary focus. These are useful exercises which can be used on recovery days. To see how a coach can balance out all of these training avenues, an excellent example of this can be seen in the attached video, with an inside look at the training undertaken by Richmond International Academic and Soccer Academy

Much of the exercises seen in this programme incorporate elements of a well-designed and balanced programme. My personal highlights of this video can be seen in a well-structured warm-up that is taken seriously, followed by some excellent potentiation work in a wonderful facility

The main finding of this study was that when compared to the other methods, the strength training intervention led to superior observable performance results than plyometric, speed, and functional training.

When analysing the data, the strength training intervention was found to enhance strength, jump, sprint, and COD performance when calculated with body mass.

Although sprint and plyometric training was found to be effective at developing jump performance in youth, the benefits were not comparable to the strength training group where an even greater improvement was seen.

Finally, based on the results of this study, functional training was found to have little to no benefit to the participants and could not be recommended as an intervention for youth soccer players.

“This study continues to champion the use of strength training with young soccer players, proving youth S&C is both ethical and effective. These results came as no surprise, as in my opinion, the functional and speed and plyometric group lacked the intensity to progress for any time period longer than 1-2 months. Therefore, if this study was to be conducted again, I would look to implement exercises that were not only more demanding on the neuromuscular system, but could be progressed on a monthly basis.”

“As participants responded well to strength training, it is important to understand the potent benefit strength training has on youth, including increased muscle hypertrophy, greater motor recruitment, increased tendon stiffness, and increased power-to-weight ratios For (HERE). years, this has been supported by researchers such as Dr Faigenbaum, who discusses the additional benefits in the attached podcast that can be experienced from strength training outside of purely performance related qualities.”

“In summary, if coaches are looking to maximise their returns on additional training, coaches should look to implement strength training under the supervision and employment of a qualified youth S&C coach.”

N utritio n

This month ’ s top research on nutrition

N utritio nal suppo rt fo r e lite yo uth athlete s: C an we do bette r?

Professional football clubs invest in youth academies to develop home-grown high-quality football players. To audit and advance these youth academies, the Elite Player Performance Plan (EPPP) was created to categorise academies from one (the best) to four (the worst), based on the support they offer the players (including facilities, coaching, opportunity, education, and welfare).

Despite sports science and medical staff being required to be employed full-time in academies with category one status, performance nutritionists are only required to be employed part-time. In categories two to four, nutrition-related services are not mandated at all.

Academy players experience similar training demands to adult players within the English Premier League and have the added physical stress of growing and maturing. Academy players present with higher relative daily energy requirements than adult counterparts (60–80 kcal.kg−1 fat free mass vs 40–60 kcal.kg−1 fat free mass).

Evidence suggests academy players consistently fall into an energy deficit, particularly during heavy training and match days. A potential consequence of this is low energy availability, which could lead to negative symptoms associated with relative energy deficiency in sport (RED-S) syndrome. This can be detrimental to long-term player development, health, and performance.

This study audited nutrition-related services provided to youth male football players within the EPPP football academies. With this information, prompt critical reflection is necessary to ensure academy players have access to quality nutritional services.

An online questionnaire was used to survey 89 football academies. The academies included 26 category-1, 18 category-2, 41 category-3, and 4 category-4.

The survey was created by the research team and nine qualified nutrition practitioners, and contained seven sections: 1) practitioner information 2) practitioner accreditations and qualifications 3) scope of nutritional services provided 4) topics of education covered 5) onsite food and drink provision 6) on-site supplement provision and management 7) monitoring of nutritional related data.

To compare scores between age groups, U9-U11 were categorised as the Foundation Phase (FP), U12-U16 as the Youth Development Phase (YDP), and U18-U23 as the Professional Development Phase (PDP).

Practical Takeaways

The nutritional support for the YDP is a particular area of improvement. At this stage of development, academy players undergo the most rapid phase of growth and maturation. However, this research shows that older players get the most investment. For practitioners in a similar setting, developing programmes and services for younger players is just as important as the young adults.

Working with young athletes in any sport requires its own considerations. Firstly, often their parents/guardians have the greatest influence over a player’s diet (for example the cooking, food shopping, finances). Educating the parents/guardian and engaging them in the process is just as important as involving the players. Secondly, understanding the players’ stage of maturity, and how that can impact the total energy and nutrients required. Thirdly, make the content simple and fun! Especially in the under-18 academy groups, long texts and complicated scientific words aren’t going to engage the players. This isn’t an exhaustive list, but hopefully it gives practitioners some ideas about what to consider when working with young athletes.

According to SENr (Sport and Exercise Nutrition register) guidelines, ergogenic supplements should not be recommended to under-18’s. Although the food first approach is preferred, Informed Sport-certified vitamins and minerals can be offered if appropriate and food is not available or easy to access.

For practitioners in competitive club settings, reflecting on the nutritional programme and services that you provide is a useful way to enhance its delivery This paper used a questionnaire to provide quantitative results, but simply asking the opinions of players, members of staff, or parents/guardians could help strengthen your approach. This paper may have also highlighted some ideas that you can implement!

In category one clubs, 64% of accredited nutritionists were employed full time, whilst 0%, 14%, and 0% of accredited nutritionists were employed full time in categories 2–4, respectively

An overriding theme was how category 1 clubs provided the most nutritional services, education, food and drink, supplements, and monitoring of nutritional related data. The most support was often provided to the PDP, followed by the YDP, and then the FP

A greater proportion of practitioners delivered the education topics ‘basics of macronutrients’, ‘basics of micronutrients’, and ‘eating for growth’ to the YDP in category 1 academies. However, the topics of ‘fuelling for games’, ‘fuelling for training’, ‘hydration’, ‘recovery’, and ‘supplements’ were delivered more to the PDP in all 4 categories. Players in the PDP were provided with breakfast, lunch, dinner, snacks, pre-match food, post-match food and fluids more frequently across all categories than younger academy players. Overall, the most common supplements provided were carbohydrates, followed by protein, electrolytes, vitamin D, and caffeine.

Anthropometrics were regularly measured (<1-3 months) in all category academies and all age groups.

“For me, this research reiterates the importance of two key points: a) investment in nutritional services in competitive sports settings, particularly in youth academies b) critical reflection on support offered to athletes.

“In my experience, most young players are willing to take on and implement strategies needed to make it to elite sport. It’s a key time to implement core nutritional principles, encourage enjoyment with cooking, and open engagement with nutritional support. It is not only for the players’ performance, but their growing and changing bodies as well. It is a crucial time for clubs to invest in nutritional support to create well-rounded high-quality players.

“In regards to how you help an athlete improve their experience and engagement with nutrition, it can take a more structured form. For example, asking athletes or staff for their opinions on your nutritional programme – or be as simple as evaluating your approach to a conversation. It’s an important tool that can be easily overlooked but underpins personal and professional development.”

C arbo hydrate fe ar, skinfo ld targets, and bo dy im age issue s in e lite fe m ale fo otball

Women’s football is growing rapidly in participation, opportunity, and professionalism. But the scope of research supporting female players is far from comparable to the men’s game. A recent audit showed the need for a ‘strategic and multidisciplinary research agenda to fill the gaps in female football research. A key area of concern was nutrition-related research, which was studied far less than other areas of sport and exercise science.

The lack of research in female football is concerning because female athletes are more susceptible to negative health outcomes associated with chronic low energy availability and relative energy deficiency in sport. Some of these negative health outcomes include disordered eating, low bone mineral density, irregular or total loss of periods, and extreme weight loss. A study by Morehen et al. (2022) showed that 88% of the England Lioness’ (recent European Champions) presented with low energy availability during a four-day training period. Additionally, although mean carbohydrate intake was 3.3g.kg-1, daily carbohydrate intake was not adjusted to daily physical training demands (i.e., an inability to fuel for the work required).

To help prevent under-fuelling in female football, it is important to understand the reasons that underpin it. On one hand, if budget allocations to nutrition and food are low, then actual provision of high-quality carbohydrates would be low and minimise the opportunity to fulfil nutritional strategies. Likewise, if a lack of education provided to the players and supporting staff on the importance of fuelling and current carbohydrate recommendations. Additionally, there may be underlying misconceptions of carbohydrates and sufficient fuelling in an environment where body composition is emphasised as a performance priority

Therefore, the aim of this study was to understand player and stakeholder perceptions of nutrition practices to improve the health and performance of female football players.

The research was gathered using semi-structured interviews with elite English female footballers (n=12), parents/guardians (n=9), technical coaches (n=9), sport scientists (n=7), nutritionists (n=5), and medical staff (n=5).

The interviews were split into three domains: (1) ‘Participant background and demographic’, (2) ‘Perceived impact of nutrition on performance with an emphasis on priorities and challenges’, and (3) ‘Female specific performance nutrition priorities and challenges’

Although the interviews followed this structure, questions were open-ended e.g., “what are your thoughts on…?” to gain the participants' opinion on these domains.

Following the collection of data, four themes were established that present a narrative of the nutrition culture within elite women s football:

1. fuelling is important but under-fuelling is common

2. carbohydrate confusion: do carbohydrates make me fat?

3. skinfold culture, body image issues and social media pressure

4. nutrition support: the current challenge and future solution

Theme 1

Most players (n=9/12) understood it was important to meet fuelling recommendations. One player commented on how energised they felt on the pitch after meeting the recommended carbohydrate intake before game day. Other stakeholders, such as coaches (n=5/9), parents (n=6/9), sport scientists (n=5/7), and medical staff (n=4/5), identified fuelling as the No. 1 performance priority. Despite this, many players and stakeholders were confused about how to fuel before a game (e.g., understanding the carbohydrate recommendations). Additionally, some concerns were raised on player health and wellbeing that is consistent with chronic low energy availability and relative energy deficiency in sport. A sport scientist mentioned “there are players in the club who have never actually had a cycle while I’ve been at the club”. Another medical staff member mentioned that players were “lethargic on the pitch” putting “them at an injury risk”.

Theme 2

As an extension of the previous conversation, many participants perceived that players were under-fuelling due to not consuming enough carbohydrates to meet the recommendations. Some staff members mentioned players had a ‘fear of carbohydrates’ and even used the term ‘carbphobic . One player mentioned “sometimes I just don’t want to eat carbs because I know they will make me fat”. Misunderstandings were also presented by parents, as a sports scientist was “asked by a parent if her daughter, aged 18, should go on a low carbohydrate diet”.

Theme 3

The challenge to simultaneously fuel whilst also meeting body composition targets was reported as a contributing factor to under-fuelling. Players’ body composition was regularly (4-8 weeks) assessed using weighing scales and skinfold, which adds to the perceived pressure to meet body composition targets. One player commented “well if I’m in red now, how am I going to get into green? The only way to get into green is not eating, eating minimally”. This, along with social media influence and pressures from some stakeholders, resulted in players being concerned with body image. A player mentioned they had “seen it (under-fuelling) first-hand affect people to a point where it’s actually ruined their careers because they’ve been more obsessed with what they look like than their football”.

Theme 4

There was a considerable difference in the sport sciences provision, particularly in nutrition-related services, between domestic-level clubs and the international team. This meant players coming to the international set-up had varying levels of nutritional knowledge. Additionally, other stakeholders also showed a lack of nutritional knowledge. This could have added to unhelpful comments from staff members which could have contributed to the previous three themes. For example, a player mentioned “you had a manager, for example, who was telling people they needed to lose weight and, you know, that’s not a

good conversation to have, not just with anyone but with a female athlete ‘cause, you know, that can have really, really bad effects on someone s mental state”. Additionally, players would seek nutrition support online and from other less nutrition-qualified stakeholders, such as sport scientists and parents. A nutritionist mentioned that correcting false nutrition-related information players had read online was “a challenge in itself”.

P ractical Takeaways

This study shows it is just as important to educate stakeholders on the importance of nutrition and implemented nutrition practices, as it is to educate the players. A performance nutritionist is one person in a multi-disciplinary team, so it is important the message around nutrition remains consistent between staff members. This can also be used to a nutritionist’s advantage, as other staff members can check on players to ensure nutritional guidelines are being met. For example, ensuring that players had eaten some food before training or consumed their recovery shake posttraining.

Approaching topics around weight, body composition, and body image between men s and women’s sports is very different. This study highlighted the importance of sensitivity around these topics in female sport. In my own applied practice, I prefer to focus on the term functional mass, rather than body fat when talking about body composition changes.

Despite this, body composition and weight still needs to be monitored in female sport; however the approach towards it and how the results are interpreted needs to be altered. An example of this is linking changes in body composition to performance parameters - for example increasing muscle mass (and therefore increasing weight) with improvements in 1 rep max squats. Also blinding the number of the weight scales to ensure players can’t see the figure. When interpreting body composition and weight results, ensure the focus is on performance and making the athletes more functional.

Developing relationships with individual players is probably the most important aspect to ensure honest and open conversations can be had around nutrition and body image. Players need to be able to trust you to open up about these topics and trust is built between two people communicating with each other regularly

James’ C o mme nts

“Outside of the athletic environment, the societal and social media pressures that women face have been thoroughly documented. Therefore, it is not surprising that those pressures translate to a female athletic environment (and are arguably amplified due to the monitoring and emphasis on body composition). This study brings light to those pressures and perceptions and collates them into a tangible report.”

“Additionally, because this study reports on the elite England women’s pathway football squads, I think it adds an additional importance on these topics. These pressures and perceptions are being experienced by some of the top athletes in female sport, who have the most up-todate support and access to top-quality staff members and provisions. But this just shows that a shift in approach around nutrition, body composition, and body image in female sport needs to change at the top of the sport, to be able to filter down.

“There is a lot to be learned from this study Women’s sport is growing rapidly, and therefore the support teams surrounding them are growing too. It is so important that those staff members supporting female athletes understand the unique pressures and perceptions they face and provide the education to their athletes as early as possible (a great podcast and video in this area is below).”

C hange s in the skin characte ristics asso ciate d with de hydratio n and re hydratio n

O BJE C TIV E

It is well known that a >2% loss of body mass from sweating could impair endurance performance and 3% could negatively impact resistance exercise performance and sport-specific technical skills.

For years, in sport, practitioners have monitored hydration status using objective methods such as body mass change and pocket (handheld) urine specific gravity refractometers. However, body mass can only be used if baseline body mass is measured reliably prior to exercise, and urine specific gravity can only be measured using urination - thus it cannot monitor dehydration in real time.

The subepidermal (beneath the skin) moisture content and the biomechanical properties of the skin are considered as major components of skin turgor (skin elasticity). It is thought that changes in skin turgor reflect subepidermal moisture conditions, and therefore potentially assess dehydration status in real time.

With this in mind, this study aimed to assess the effects of dehydration and rehydration on the skin characteristics in young healthy men in order to see if skin characteristics could be a tool to measure hydration status.

WHAT THE Y DID

In a randomised cross-over study design, 20 young healthy men (aged 25 years) were recruited to complete three trials (separated by at least three days) after exercise. The trials were:

1. no fluid intake

2. ad libitum (as much or as often as necessary or desired) intake and

3. programmed fluid intake

On the evening prior to the trial, participants consumed 500ml of commercialised sports drink (6.2% carbohydrate) and another 500ml of the same drink 120 minutes prior to the trial. The exercise trial involved cycling at 60 RPM and 60% of heart rate reserve (i.e. the difference between a resting heart rate and maximum heart rate) for 20 minutes followed by a five-minute resting period. This was repeated until participants reached 2% body mass loss in a climate-controlled room at 35°C (95°F ) and 30% relative humidity

Body mass was measured at each resting period. Biomechanical properties of the skin were measured using a handheld dermal phase metre device at the corner of the eye, the medial side of the forearm, the back of the hand between the first and second fingers, and the anterior abdomen. Using this device, measurements were taken three times at each point and measured for pliability, portion of the viscoelasticity, and the total recovery of the skin pre and post intervention.

Blood samples were also measured for the following: Urea nitrogen, serum osmolality, sodium, potassium, chlorine, creatinine, haemoglobin, haematocrit, arginine vasopressin, and atrial natriuretic peptide to see if haematocrit data correlates with properties of the hand.

P ractical Takeaways

This study was the first to investigate the effect of dehydration and rehydration on the TDC and biomechanical properties of the skin upon instrumental measure, and not manual testing. This provides practitioners a tool to measure when out of the laboratory and in real world scenarios (i.e., the side of a pitch, or in the mountains with a cycling team).

This study confirmed the decline in aerobic capacity by dehydration and immediate recovery with sufficient rehydration. Therefore, it is important to ensure your athlete starts exercise performance sufficiently hydrated (fluid pre-exercise, light coloured urine, no dry mouth) and has an individual rehydration strategy in place (i.e. chocolate milk, a cold slushy and a sports drink).

Changes in the TDC and the biomechanical properties of the skin correlated with the body water and dehydration-associated indicators in the serum and urine.

Skin characteristics, particularly on the hand, may be useful in the assessment of dehydration; however, further studies regarding the aspiration probe, dehydration method, and exercise type are required.

WHAT THE Y FO U N D

The study showed there were significantly higher values of pliability and viscoelasticity and lower values for the total recovery on the hand skin in the hydrated trial compared to the dehydration trial. All changes in the tissue dielectric constant correlated significantly with markers in the blood, total body water, serum osmolarity and body mass.

The study confirmed ad libitum drinking (Ad libitum 0.88 L programmed 1.72 L) could not adequately recover hydration status; thus, it is necessary for dehydration prevention to determine the amount of fluid intake using objective indicators related to dehydration in real time.

Relating to the hand, all changes in the biochemical properties were significantly correlated with changes in body mass, haematocrit and urine specific gravity

The present study showed the changes in skin characteristics correlated with the body water and dehydration-associated indicators in the serum and urine, thus suggesting skin characteristics may be useful in the assessment of dehydration.

“Hydration has been an interesting topic of discussion at all clubs I have ever worked at. The classic questions around dehydration and cramp always crop up and as far as I am aware there is no conclusive evidence to show hydration is linked to cramping. Having said this, it always surprises me how many players do not drink enough and seem to under-appreciate the impact 2% dehydration can have on performance.

“I always try to encourage my players to have a glass of water next to their bed to drink when they first wake up, sip fluids throughout the day little and often, and to trust their thirst mechanism - if they feel like they have a dry mouth, then drink. Additionally, milk is always a winner in the heat and with hydration levels has been shown to hydrate better than water!

“The tool used in the study provides a handy way to measure skin characteristics; however, I am not convinced this is the best use of time for most nutritionists at clubs - a nutritionist might better spend their time educating players on what to eat, how much to eat and at what times of the day.”

Injury P reve ntio n & Re hab

This month ’ s top research on injury prevention and rehabilitation.

S ingle vs. double leg counter movem

W hich provides a better or more acc of asy mmetry ?

S ingle vs. do uble le g co unte r m ov e m e nt jum p:

The double leg and single leg countermovement jumps (CMJ) are staples in the performance and return-to-sport world after lower extremity injury The argument for the single leg CMJ is that it can provide information on an injured limb in isolation when assessing movement quality, as well as a valid measurement of a limb’s strength and power The argument for the inclusion of the double leg counter movement jump is that higher forces can be spread across both legs and can better reveal off loading and compensatory strategies of an injured limb.

The purpose of this article summary was to compare jump performance qualities in the single vs double leg CMJ, as well as to determine if this information can enhance exercise prescription and progression decisions through rehabilitation and return to sport.

P ractical Takeaways

The double leg CMJ test was discussed in detail as to why it is a core test that should be assessed in athletes post anterior cruciate ligament reconstruction (ACLR). In addition, researchers discussed why the single leg CMJ is also a valuable tool to be used in conjunction.

The different demands of each jump test were identified and as a result provide different objective information that will help clinicians assess movement quality in athletes’ lower extremity injuries.

Asymmetries were resolved quicker in single leg jumps versus double leg because the overall magnitude of force, depth of countermovement, and speeds of loading were decreased compared to bilateral jumps (ie. an athlete at six months postoperation may show a 90% limb symmetry index (LSI) in a single leg (SL) CMJ but a 70% LSI on a double leg (DL) CMJ).

Double leg activities provide more options to unload the previously injured knee, primarily via inter-limb compensatory or avoidance strategies.

Decrements in performance of an uninjured limb undermine the value of a LSI as seen in hop tests during return-to-sport. It does not mean that the underlying functional deficits have been fully analysed and addressed.

In the post-ACLR athlete, attention to observed force reduction and deceleration qualities with varied load, loading rates and velocity demands is warranted to better understand individual response to loading during rehabilitation, as well as informing prescription.

The DL-CMJ generates a single, rapid and simple test to implement, making it an essential practical tool for frequent monitoring during and post return-to-sport, as well as athlete performance to identify asymmetries and strategies.

Inadequate acceleration in the countermovement descent is like testing car brakes at 5mph; yes it provides information, but would you consider data obtained under those conditions valuable in informing decisions you need to make on the readiness of those brakes for use on the highway at 70mph?.

“For clinicians and coaches without the ability to use force plates, I recommend using the ‘My jump 2’ app. It is a quick and easy way of obtaining valuable data for quantifying the DL and SL CMJ (See HERE). Landing asymmetries are a secondary risk factor for subsequent ACL injuries, so eccentric control and deceleration should be a staple and trained in rehabilitation.”

“From this article summary, I think it is important to understand that one CMJ is not necessarily better than the other - they both provide different data on athlete readiness and both should be included in the return-to-sport decision making process.”

Then check the se out...