TASTER EDITION
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
SUMMARY – FOR STRENGTH COACHES AND PERSONAL TRAINERS Bench press and push-up at The researchers concluded that the bench press and elastic-band-resisted push-up comparable levels of muscle activity produce similar levels of EMG activity in the pectoralis major or anterior deltoid muscles. results in similar strength gains Additionally, they concluded that both of these exercises produce similar strength gains as assessed in a Smith machine bench press test in resistance-trained individuals over a 6week training period. Early adaptations to six weeks of non-periodized and periodized strength training regimens in recreational males
The researchers concluded that in volume-matched resistance-training programs, there is no difference between periodized and non-periodized training methods (whether daily undulating or block periodization) over short periods of time for increasing muscular size. However, for increasing muscular strength, a daily-undulating periodized program may be optimal.
Effect of movement velocity during resistance training on neuromuscular performance
The researchers concluded that training at maximal velocity instead of half of maximal velocity during a linear periodized resistance-training program comprising back squats led to significantly better gains in both maximal back squat strength and countermovement jumping height. However, neither fast nor slow resistance-training using the back squat exercise improved sprint running time over 10m or 20m.
Effects of instability versus traditional resistance training on strength, power and velocity in untrained men
The researchers concluded that both traditional circuit resistance-training and unstable exercise circuit training are similarly effective for increasing muscular strength, power, and movement velocity in untrained males.
The effects of tapering on powerforce-velocity profiling and jump performance in professional rugby league players
The researchers concluded that a 21-day taper involving an immediate reduction from 3 – 4 days of resistance-training per week to a single day of resistance-training per week was effective for increasing maximal power output and loaded jump height performance in professional rugby league players.
Transference of traditional versus complex strength and power training to sprint performance
The researchers concluded that for improving short-distance (20m) sprint running performance in moderately trained subjects, the traditional model of periodizing training into successive blocks is superior to the complex model of training using all methods at the same time.
Effect of load on peak power of the bar, body and system during the deadlif
The researchers concluded that peak power output during the deadlift differs depending on whether the bar, body, or system variables are analyzed. System peak power output was significantly greater between 30 – 70% of 1RM than >70% of 1RM.
Neuromuscular response differences The researchers found that the lightest load produced the greatest power output and to power vs. strength back squat impulse but the shortest repetition duration during the explosive squats. They found that exercise in elite athletes peripheral fatigue occurred during the heavy and moderate conditions but not after the light loading condition. They noted that power output declined during the performance of the squats only in the heavy group. On this basis, they suggest that moderate-load squats might be best for power development. Intensity rankings of plyometric exercises using joint power absorption
The researchers concluded that ranking plyometrics exercises by joint peak power and by the sum of joint powers could be useful for strength and conditioning coaches or rehabilitation professionals looking to progress athletes, clients or patients over the course of a program with respect to a specific adaptation.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 2
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
SUMMARY – FOR SPORTS MEDICINE PHYSICIANS AND PHYSIOTHERAPISTS Do structural changes (e.g. collagen/matrix) explain the response to therapeutic exercises in tendinopathy: a systematic review
The reviewers concluded that there is no good evidence to support the association of observable structural changes with the beneficial clinical outcomes that are currently associated with therapeutic exercise overall. However, they also noted that there is some moderate evidence to support an association between structural changes and beneficial clinical outcomes in relation to conventional heavy resistance-training alone. They suggested that this may imply that the mechanisms by which eccentric exercise is effective are not primarily morphological but may instead include neural, biochemical and myogenic changes.
Intra and inter-rater reliability of the selective functional movement assessment (SFMA)
The researchers concluded that while intra-rater reliability for the SFMA was generally substantial-to-excellent irrespective of the exact scoring method used, inter-rater reliability was only poor-to-substantial.
Roller massager improves range of The researchers concluded that while both interventions improved flexibility, selfmotion of plantar flexor muscles without massage with a roller massager led to small improvements in force production subsequent decreases in force parameters relative to the static stretching condition at 10 minutes post-intervention. Specific and cross over effects of massage for muscle soreness – randomized controlled trial
The researchers concluded that massage using a foam rolling device reduces muscle soreness and increases pressure pain threshold at 48 hours post-workout. They concluded that there was also a tendency towards a soreness-reducing effect in the contralateral limb which may indicate the existence of a cross-over effect through central pathways.
Effects of kinesio-taping on skeletal muscle strength — a meta-analysis of current evidence
The reviewers concluded that application of kinesiological tape does not lead to strength gains in healthy adults.
Clinical effectiveness of kinesiological taping on pain and pain-free shoulder range of motion in patients with shoulder impingement syndrome – a randomized, double blinded, placebo-controlled trial
The researchers concluded that kinesiological taping produces an immediate improvement in pain during movement and in nocturnal pain in subjects with shoulder impingement syndrome.
No strong evidence that the addition of joint mobilisation to an exercise programme improves outcomes for shoulder dysfunction
The reviewers found that adding joint mobilization to a therapeutic program of exercise does not confer additional benefit in respect of pain measures for patients with shoulder dysfunction.
The effect of knee extensor open kinetic chain resistance training in the ACLinjured knee
The researchers concluded that low relative-load open kinetic chain knee extension exercise led to a reduction in anterior knee laxity in an ACL-injured knee compared to either a standard program or a standard program plus high relative-load open kinetic chain knee extension exercise.
The activity pattern of the lumbopelvic muscles during prone hip extension in athletes with and without hamstring strain injury
The researchers concluded that athletic individuals who have previously incurred a hamstring strain injury display greater levels of EMG activity in the medial hamstrings and the gluteus maximus than those who had not previously incurred a hamstring strain injury.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 3
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
INTRODUCTION Chris Beardsley says‌ There were a couple of themes we could have gone with for this edition but I quickly put a vote in for The Push-Up Edition, as I think this exercise gets a really poor showing in most programs. Despite being very easily loaded up with either elastic bands or weighted vests, too many people relegate it to conditioning or finishers, or just assume they have advanced beyond it. Here, we find that not only is the humble push-up able to go toe-to-toe with the bench press when loaded up using elastic resistance but it's also an extremely versatile exercise that can be tweaked to create different loading on each of the prime mover muscles or even on different heads of the pectoralis major itself. If these extraordinary features aren't enough to get you putng the push-up back into your programs (if it is not there already) then I don't know what is.
The Push-Up Edition In Bench press and push-up at comparable levels of muscle activity results in similar strength gains, the researchers evaluated EMG levels during a 6RM bench press and elasticband resisted push-up. In this trial, the researchers used surface electrodes to record EMG activity from the sternocostal head of the pectoralis major and from the anterior deltoid. They normalized these data using values obtained during maximum voluntary isometric contractions (MVIC) and expressed them as a percentage of the maximum EMG activity levels. The researchers reported that there was no significant difference in the EMG activity levels of either the pectoralis major or anterior deltoid muscles between the 6RM bench press and the elastic-band-resisted push-up. Indeed, the EMG activity levels in both muscles appeared almost identical. In the same study, but a second part, the researchers evaluated strength gains following a 5-week period in which either the bench press or push-up were performed but in which all other training variables (i.e. relative load, volume, rest, exercise technique and speed of movement) were controlled. The subjects were 30 university students with resistance-training experience and 1RM strength gains were assessed using a Smith machine bench press test. The training involved 2 sessions per week for 25 minutes per session in which the subjects performed 5 sets of 6 repetitions with 4 minutes of inter-set rest using the previously attained 6RM. The researchers found that both the bench press group and elasticband-resisted push-up group improved 1RM and 6RM significantly from pre- to post-testing. However, they did not detect any significant differences in the increase in strength between the two groups. Indeed, the increase in both groups was very similar, being 22% in the bench press group and 21% in the push-up group. In Muscle activation during push-ups with different suspension training systems, the researchers compared the EMG activity of the prime mover muscles (the pectoralis major, triceps brachii and anterior deltoid) during push-ups with and without suspension devices to create instability. They also compared the effects of different suspension devices, with one anchor, with two anchors, and with one anchor and a pulley system.
The one anchor system was created using a TRX device, the one-anchor with a pulley was created using an AirFit Trainer Pro, and the two-anchor system was created using a Jungle Gym XT. For subjects, the researchers recruited 29 young male university students who performed 3 push-ups in each of the 4 different suspension systems, as well as on the floor. The researchers found that for recruiting the triceps brachii, the most effective exercise was the suspension device with one anchor. For recruiting the anterior deltoid, the floor push-up was the most effective. For the pectoralis major, the twoanchor suspension device was better than all other options. Thus, each of the prime movers can be emphasized using a different push-up variation. Finally, in The effects of push-ups with the trunk flexed on the shoulder and trunk muscles, the researchers compared the EMG activity of the shoulder and trunk muscles in two push-up positions: standard push-ups and push-ups with 30 degrees of trunk flexion. By flexing the trunk, this position alters the angle at which the prime movers must push against the ground and also has an effect on the amount of work the core muscles must do in order to stabilize the trunk. For subjects, the researchers recruited 15 young adult males. They recorded the EMG activity of the clavicular and sternocostal portions of the pectoralis major, the serratus anterior, and the rectus abdominis. The researchers found that the EMG activity of the sternocostal part of the pectoralis major was significantly greater in the standard push-up position than in the trunk flexed position but the reverse was the case for the clavicular portion. Thus, different push-up variations were able to place a different amount of stress on different heads of the pectoralis major. It seems likely that there would have been a different amount of EMG activity in the anterior deltoid as well but this was not measured. All of this exciting research has important practical implications for both strength development and for muscular hypertrophy. In respect of strength development, we can see that the pushup exercise can easily be loaded effectively using elastic resistance bands and, in such conditions, that the movement pattern is very similar to the bench press. Thus, it likely makes a very useful assistance exercise for improving the bench press since it can probably be performed in higher volumes with lesser risk of injury. Indeed, the strength gains seen over a longterm training study showed that the push-up training transferred to the bench press test as effectively as bench press training itself. For muscular hypertrophy, we can see that different variations of the bench press can be used to place greater stress on different prime movers (by using unstable surfaces of varying kinds) and also on different heads of the pectoralis major (by using trunk flexion). Thus, it is a very versatile lift that should be in the toolbox of every strength and conditioning coach and personal trainer. With that, I shall leave you to the reviews. I hope you enjoy reading this edition and I look forward to seeing what next month's research holds! Chris.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 4
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
INTRODUCTION continued… Bret Contreras says…
Passive muscle length changes affect twitch potentiation in power athletes This is interesting stuff. There’s so much more to learn about PAP.
Transference of traditional versus complex strength and power training to sprint performance I really liked learning about the transfer effect correlation formula that the researchers used in this study. Very cool!
Sarcomere length organization as a design for cooperative function amongst all lumbar spine muscles I tried to address this in a T-Nation article a couple of years ago to explain why people round during deadlifts. The editors changed the title and made it seem as if I’m espousing round-back deadlifting, and the strength coaches were irate. Good times. Anyway, there are a few reasons why people may round (decreased hip ROM, increased passive support, decreased external hip extension moment, increased IAP, etc.), but another reason is that many of the core muscles are designed to operate best in flexion. Nevertheless, not everyone is stronger when rounding. I tested isometric DL strength on a force plate in different postures and it really depends on the subject.
Exercise selection to develop optimal explosive lunge movements for world-standard squash I appreciated the authors’ lunge progression model in this article.
Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters Hip extension is important out of the blocks.
Range of motion and leg rotation affect EMG activation levels of the superficial quadriceps muscles during leg extension I love this kind of stuff. I’ve actually been experimenting with this line of EMG research in my lab (garage gym) with various muscles.
Changes in contractile and elastic properties of the triceps surae muscle induced by neuromuscular electrical stimulation training I’ve always been intrigued by EMS, ever since I read the work of the late Charlie Francis. I sometimes dream of owning some crazy laboratory with athletes hooked up to all sorts of gadgets. EMS would be something I’d delve into.
Welcome back to another month of S&C Research! As usual, this month's research was terrific. Here are my favorite studies: Bench press and push-up at comparable levels of muscle activity results in similar strength gains This was a fascinating paper. I think that many strength coaches would have predicted the outcomes, but it’s always very nice to have a study to reference.
Regional differences in muscle activation during hamstrings exercise Last year I was involved in a study with my friend Jurdan Mendiguchia where we examined upper versus lower hamstring muscle damage in the lunge and eccentric leg curl using fMRI. Brad and I have been discussing hamstring EMG for years, so it’s nice to finally complete our study. We hypothesized that, similar to the MRI study with Jurdan, the SLDL would lead to greater upper hamstring activation while the lying leg curl would lead to greater lower hamstring activation, but we were only partially correct. The lying leg curl is superior to the SLDL for activating the lower hamstring fibers.
A systematic review and meta-analysis examining the effect of eating rate on energy intake and hunger Simply advising overweight/obese clients to eat slower can be a useful strategy to help them lose weight.
Muscle activation during push-ups with different suspension training systems Another intriguing push-up study. Suspension with two anchors for greatest pec activation.
The effects of 12 weeks of beta-hydroxy-beta-methyl-butyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebocontrolled study I’d like to see this study duplicated. Not trying to be Debbie Downer here, but these results are very impressive, and it’s hard to imagine that a supplement that never really caught on with serious lifters is responsible.
The effects of push-ups with the trunk flexed on the shoulder and trunk muscles It makes sense – flex the hips to create more of an “incline-press” type push-up to better recruit the upper pecs.
Effect of caffeine ingestion on torque and muscle activity during resistance exercise in men Very cool! Caffeine works, and it works even better for high speed activities.
Effect of load on peak power of the bar, body and system during the deadlif Very interesting! In my blogposts I’ve quoted past research (Swinton) showing that peak power in the deadlift occurs at very low loads (3040%), and based on this new research, I was in error. It’s important to look at the whole system (body plus bar). When the system is analyzed, the load that maximizes peak power in the deadlift is 70% of 1RM, but there’s no significant difference between 30% and 70%, so high power outputs are achievable with a broad range of loads, similar to that seen in Olympic lifts.
Specific and cross over effects of massage for muscle soreness – randomized controlled trial This is an excellent paper that shows that foam rolling works at least in part by central mechanisms.
Intensity rankings of plyometric exercises using joint power absorption This is a very useful study that indicates that a variety of plyometric exercises are needed to maximize the training effect on the primary joints involved in jumping and landing. Do changes in muscle architecture affect post-activation potentiation? I’m very intrigued by this line of research and am considering purchasing an ultrasound unit so I can conduct my own experiments.
The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee This study shows that leg extensions, a seemingly not-very-functional exercise, can be very functional depending on the goal (ex: improving knee laxity post ACL-injury). Perceived loading and muscle activity during hip strengthening exercises – comparison of elastic resistance and machine exercises Good to see here that you don’t have to spend thousands of dollars on adduction/abduction machines – some $10 bands can deliver a similar stimulus and save you a lot of space in the gym. I’ve always been big on band hip abduction work with my clients. Okay folks, that's all for this month, I hope you enjoy this edition! - Bret
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 5
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
CONTENTS 1. STRENGTH & CONDITIONING, POWER AND HYPERTROPHY........................................................................................... 9 1.
Bench press and push-up at comparable levels of muscle activity results in similar strength gains, Calatayud, Borreani, Colado, Martin, Tella, and Andersen, in Journal of Strength and Conditioning Research Publish Ahead of Print ................................................................ 10
2.
Early adaptations to six weeks of non-periodized and periodized strength training regimens in recreational males, by Souza, Ugrinowitsch, Tricoli, Roschel, Lowery, Aihara, Leão and Wilson, in Journal of Sports Science and Medicine, 2014 .................................11
3.
Strength gains afer ten-weeks of daily non-linear periodization between concurrent versus resistance training, by De Souza Bezerra, Paz, Rossato, Neto, and Miranda, in Medicina Sportiva, 2014................................................................................................................... 12
4.
Effect of movement velocity during resistance training on neuromuscular performance, by Pareja-Blanco, Rodríguez-Rosell, SánchezMedina, Gorostiaga and González-Badillo, in International Journal of Sports Medicine, 2014 ..................................................................13
5.
Effects of instability versus traditional resistance training on strength, power and velocity in untrained men, by Maté-Muñoz, Antón, Jiménez and Garnacho-Castaño, in Journal of Sports Science and Medicine, 2014 .................................................................................... 14
6.
Effects of traditional versus alternating whole-body strength training on squat performance, by Ciccone, Brown, Coburn, and Galpin, in Journal of Strength and Conditioning Research Publish Ahead of Print ...................................................................................................... 15
7.
The effects of tapering on power-force-velocity profiling and jump performance in professional rugby league players, by De Lacey, Brughelli, McGuigan, Hansen, Samozino, and Morin, in Journal of Strength and Conditioning Research Publish Ahead of Print .............16
8.
Increases in intracellular water explain strength and power improvements over a season, by Silva, Matias, Santos, Rocha, Minderico, and Sardinha, in International Journal of Sports Medicine, 2014 ................................................................................................................17
9.
Effect of sprint training – training once daily versus twice every second day, by Ijichi, Hasegawa, Morishima, Kurihara, Hamaoka & Goto, in European Journal of Sport Science, 2014....................................................................................................................................... 18
10. Transference of traditional versus complex strength and power training to sprint performance, by Loturco, Tricoli, Roschel, Nakamura, Abad, Kobal, Gil, and González-Badillo, in Journal of Human Kinetics volume, 2014 ................................................................................. 19 11. Acceleration and sprint profiles of a professional elite football team in match play, by Ingebrigtsen, Dalen, Hjelde, Drust & Wisløff, in European Journal of Sport Science, 2014.....................................................................................................................................................20 12. Exercise selection to develop optimal explosive lunge movements for world-standard squash, by Turner and Barker, in Strength and Conditioning Journal, 2014.......................................................................................................................................................................... 21
2. BIOMECHANICS AND MOTOR CONTROL...................................................................................................................... 22 13. Range of motion and leg rotation affect EMG activation levels of the superficial quadriceps muscles during leg extension, by Signorile, Lew, Stoutenberg, Pluchino, Lewis, and Gao, in Journal of Strength and Conditioning Research Publish Ahead of Print ..........................23 14. Regional differences in muscle activation during hamstrings exercise, by Schoenfeld, Contreras, Tiryaki-Sonmez, Wilson, Kolber, and Peterson, in Journal of Strength and Conditioning Research Publish Ahead of Print .................................................................................. 24 15. Muscle activation during push-ups with different suspension training systems, by Calatayud, Borreani, Colado, Martín, Rogers, Behm and Andersen, in Journal of Sports Science and Medicine, 2014 .................................................................................................................25 16. The effects of push-ups with the trunk flexed on the shoulder and trunk muscles, by Kang, Jung, Nam, Shin, and Yoo, in Journal of Physical Therapy Science, 2014....................................................................................................................................................................26 17. Effect of load on peak power of the bar, body and system during the deadlif, by Blatnik, Goodman, Capps, Awelewa, Triplett, Erickson and McBride, in Journal of Sports Science and Medicine, 2014 ...................................................................................................................27 18. Neuromuscular response differences to power vs. strength back squat exercise in elite athletes, by Brandon, Howatson, Strachan, and Hunter, in Scandinavian Journal of Medicine & Science in Sports, 2014 ..................................................................................................... 28 19. Intensity rankings of plyometric exercises using joint power absorption, by Van Lieshout, Anderson, Shelburne, and Davidson, in Clinical Biomechanics, 2014..................................................................................................................................................................................... 29 20. Do changes in muscle architecture affect post-activation potentiation? By Reardon, Hoffman, Mangine, Wells, Gonzalez, Jajtner, Townsend, McCormack, Stout, Fragala and Fukuda, in Journal of Sports Science and Medicine. 2014 .....................................................30 21. Passive muscle length changes affect twitch potentiation in power athletes, by Gago, Marques, Marinho, and Ekblom, in Medicine & Science in Sports & Exercise, 2014............................................................................................................................................................... 31 22. Muscle activity and spine load during pulling exercises – influence of stable and labile contact surfaces and technique coaching, by McGill, Cannon, and Andersen, in Journal of Electromyography and Kinesiology, 2014 ............................................................................ 32 23. Elevation and orientation of external loads influence trunk neuromuscular response and spinal forces despite identical moments at the L5-S1 level, by Ouaaid, Shirazi-Adl, Plamondon, and Arjmand, in Journal of Biomechanics, 2014 .............................................................33 24. Sarcomere length organization as a design for cooperative function amongst all lumbar spine muscles, by Zwambag, Ricketts, and Brown, in Journal of Biomechanics, 2014.................................................................................................................................................... 34
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
25. Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters, by Bezodis, Salo & Trewartha, in European Journal of Sport Science, 2014.............................................................................................................................. 35 26. Changes in contractile and elastic properties of the triceps surae muscle induced by neuromuscular electrical stimulation training, by Grosset, Canon, Pérot, and Lambertz, in European Journal of Applied Physiology, 2014 ...........................................................................36 27. Spinal and supraspinal motor control predictors of rate of torque development, by Johnson, Kipp, Norcross, and Hoffman, in Scandinavian Journal of Medicine & Science in Sports, 2014...................................................................................................................... 37
3. ANATOMY, PHYSIOLOGY AND NUTRITION...................................................................................................................38 28. A systematic review and meta-analysis examining the effect of eating rate on energy intake and hunger, by Robinson, Almiron-Roig, Rutters, De Graaf, Forde, Smith, Nolan, and Jebb, in American Journal of Clinical Nutrition 2014 ............................................................ 39 29. The effects of 12 weeks of beta-hydroxy-beta-methyl-butyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study, by Wilson, Lowery, Joy, Andersen, Wilson, Stout, Duncan, Fuller, Baier, Naimo and Rathmacher, in European Journal of Applied Physiology, 2014 ............................................................ 40 30. Creatine supplementation post-exercise does not enhance training-induced adaptations in middle to older aged males by Cooke, Brabham, Buford, Shelmadine, McPheeters, Hudson, Stathis, Greenwood, Kreider, and Willoughby, in European Journal of Applied Physiology, 2014.......................................................................................................................................................................................... 41 31. Considerations for protein intake in managing weight loss in athletes, by Murphy, Hector, and Phillips, in European Journal of Sport Science, 2014................................................................................................................................................................................................42 32. Effect of caffeine ingestion on torque and muscle activity during resistance exercise in men, by Duncan, Thake and Downs, in Muscle & Nerve, 2014.................................................................................................................................................................................................. 43 33. Carbohydrate availability and exercise training adaptation – too much of a good thing? Bartlett, Hawley, and Morton, in European Journal of Sport Science, 2014..................................................................................................................................................................... 44 34. Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation, and other metabolic risk factors – a randomized controlled trial, by Juanola-Falgarona, Salas-Salvado, Ibarrola-Jurado, Rabassa-Soler, Díaz-Lopez, Guasch-Ferre, Hernandez-Alonso, Balanza, and Bullo, in American Journal of Clinical Nutrition, 2014 ............................................................................ 45 35. Acute exercise ameliorates differences in insulin resistance between physically active and sedentary overweight adults, by Nelson and Horowitz, in Applied Physiology: Nutrition and Metabolism, 2014.............................................................................................................46 36. Ibuprofen treatment blunts early translational signaling responses in human skeletal muscle following resistance exercise, by Markworth, Vella, Figueiredo and Cameron-Smith, in Journal of Applied Physiology, 2014 ...................................................................... 47 37. The effects of two different doses of calcium lactate on blood pH, bicarbonate, and repeated high-intensity exercise performance, by Painelli, Da Silva, De Oliveira Junior, De Oliveira, Benatti, Rabelo, Guilherme, Lancha Junior, and Artioli, in International Journal of Sport Nutrition and Exercise Metabolism, 2014....................................................................................................................................................48
4. PHYSICAL THERAPY AND REHABILITATION...................................................................................................................49 38. Do structural changes (e.g. collagen/matrix) explain the response to therapeutic exercises in tendinopathy: a systematic review, by Drew, Smith, Littlewood, and Sturrock, in British Journal of Sports Medicine, 2014 ...................................................................................50 39. Current concepts of rotator cuff tendinopathy, by Factor and Dale, in The International Journal of Sports Physical Therapy, 2014 ........51 40. Intra and inter-rater reliability of the selective functional movement assessment (SFMA), by Glaws, Juneau, Becker, Di Stasi, and Hewett, in The International Journal of Sports Physical Therapy, 2014...................................................................................................... 52 41. Roller massager improves range of motion of plantar flexor muscles without subsequent decreases in force parameters, by Halperin, Aboodarda, Button, Andersen, and Behm, in The International Journal of Sports Physical Therapy, 2014 ................................................53 42. Specific and cross over effects of massage for muscle soreness – randomized controlled trial, by Jay, Sundstrup, Søndergaard, Behm, Brandt, Særvoll, Jakobsen, and Andersen, in The International Journal of Sports Physical Therapy, 2014 ................................................ 54 43. Clinical effectiveness of kinesiological taping on pain and pain-free shoulder range of motion in patients with shoulder impingement syndrome – a randomized, double blinded, placebo-controlled trial, by Shakeri, Keshavarz, Arab, and Ebrahimi, in The International Journal of Sports Physical Therapy, 2014.....................................................................................................................................................55 44. Effects of kinesio-taping on skeletal muscle strength — a meta-analysis of current evidence, by Csapo and Allegre, in Journal of Science and Medicine in Sport, 2014........................................................................................................................................................................ 56 45. No strong evidence that the addition of joint mobilisation to an exercise programme improves outcomes for shoulder dysfunction, by Brudvig, in British Journal of Sports Medicine, 2014................................................................................................................................... 57 46. The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee, by Barcellona, Morrissey, Milligan, Clinton, and Amis, in Knee Surgery, Sports Traumatology, Arthroscopy, 2014........................................................................................................ 58 47. Perceived loading and muscle activity during hip strengthening exercises – comparison of elastic resistance and machine exercises, by Brandt, Jakobesen, Thorborg, Sundstrup, Jay and Andersen, in The International Journal of Sports Physical Therapy, 2014 ...................59 48. Radiological examination of the hip clinical indications, methods, and interpretation – a clinical commentary, by Reis, Rabelo, Pereira, Polesello, Martin, Lucareli, and Fukuda, in The International Journal of Sports Physical Therapy, 2014 ................................................... 60
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
49. The activity pattern of the lumbopelvic muscles during prone hip extension in athletes with and without hamstring strain injury, by Emami, Arab, and Ghamkhar, in The International Journal of Sports Physical Therapy, 2014 ...................................................................61 50. The effect of hip abductor muscle fatigue on frontal plane knee projection angle during step landing, by Herrington, in International Journal of Athletic Therapy & Training, 2014.............................................................................................................................................. 62
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Strength and Conditioning Research STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
1. STRENGTH & CONDITIONING, POWER AND HYPERTROPHY
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Bench press and push-up at comparable levels of muscle activity results in similar strength gains, Calatayud, Borreani, Colado, Martin, Tella, and Andersen, in Journal of Strength and Conditioning Research Publish Ahead of Print
Background Electromyography (EMG) is a commonly-used method in sports science that can help researchers understand how strongly a muscle is contracting. Exercises that display high EMG levels in certain muscle groups are thought to be those that are most effective for developing those parts of the body. A corollary of this idea is that exercises that display similar EMG levels in certain muscle groups will lead to similar gains in muscular strength and size. The bench press and the push-up are two commonly-used, upper-body horizontally-directed pushing exercises. Many previous studies have ascertained that these two exercises are biomechanically quite similar. It is often thought that the bench press has an advantage over the push-up in that it can be performed with a wide range of relative loads. However, the push-up can also be externally-loaded in at least two ways: a weighted vest, and elastic resistance. It might therefore be expected that when using loading protocols where EMG activity levels are similar, performing either the push-up or the bench press would lead to similar strength gains.
What did the researchers do? The researchers performed a two-part study. Firstly, they evaluated EMG levels during a 6RM bench press and elasticband resisted push-up. In this trial, the researchers used surface electrodes to record EMG activity from the sternocostal head of the pectoralis major and from the anterior deltoid. They normalized these data using the mean root mean square (RMS) values obtained during maximum voluntary isometric contractions (MVIC) and expressed them as a percentage of the maximum EMG activity levels. The MVIC position for the sternocostal head of the pectoralis major was the bench press with the elbow flexed to 90 degrees and the shoulder abducted to 45 degrees. The MVIC position for the anterior deltoid was shoulder flexion at 90 degrees in a seated position using an upright posture with no back support. Secondly, the researchers evaluated strength gains following a 5-week period in which either the bench press or push-up were performed but in which all other training variables (i.e. relative load, volume, rest, exercise technique and speed of movement) were controlled. The study was performed in 30 university students with resistance-training experience and 1RM strength gains were assessed using a Smith machine bench press test. The training involved 2 sessions per week for 25 minutes per session in which the subjects performed 5 sets of 6 repetitions with 4 minutes of inter-set rest using the previously attained 6RM. The load was not progressed through the training period.
What happened? Comparison of EMG activity The researchers reported that there was no significant difference in the EMG activity levels of either the pectoralis major or anterior deltoid muscles between the 6RM bench press and the elastic-band-resisted push-up. Indeed, the EMG activity levels in both muscles appeared almost identical. Comparison of strength gains The researchers found that both the bench press group and elastic-band-resisted push-up group improved 1RM and 6RM significantly from pre- to post-testing. However, they did not detect any significant differences in the increase in strength between the two groups. Indeed, the increase in both groups was very similar, being 22% in the bench press group and 21% in the push-up group.
What did the researchers conclude? The researchers concluded that the bench press and elasticband-resisted push-up produce similar levels of EMG activity in the pectoralis major or anterior deltoid muscles. Additionally, they concluded that both of these exercises produce similar strength gains as assessed in a Smith machine bench press test in resistance-trained individuals over a 6-week training period.
Limitations The study was limited in that the researchers did not record the EMG activity of the triceps brachii, which is also a key prime mover in the bench press and push-up exercise. Additionally, it is unfortunate that the researchers only tested the use of elastic bands and not weighted vests.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 10
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Early adaptations to six weeks of non-periodized and periodized strength training regimens in recreational males, by Souza, Ugrinowitsch, Tricoli, Roschel, Lowery, Aihara, LeaĚƒo and Wilson, in Journal of Sports Science and Medicine, 2014
Background Periodization has been proposed to lead to superior gains in muscular strength and size when applied to resistancetraining programs. There are two main periodization approaches, the classic model, which progresses from highvolume, low-relative load training to low-volume highrelative load training over time, and the more modern undulating periodization model, which alternates between high-volume low-relative load training and low-volume high-relative load training within a much shorter training cycle. The classic model can be further subdivided into the linear periodization model, which progresses volume and relative load consistently by reducing volume and increasing relative load on a week-by-week basis, the reverse linear periodization model, which progresses volume and relative load consistently by increasing volume and decreasing relative load on a week-by-week basis, and the block periodization model, which follows a similar pattern but uses similar loading protocols for longer cycles and makes changes in parameters in a step-wise fashion (hence “block� periodization). These blocks are designed to achieve specific training goals and are often referred to by their names, such as strength, hypertrophy, and power. Although linear and block periodization have distinctly different origins and were designed separately, they are often confused in both the literature and by coaches. Similarly, the modern undulating periodization model can be further subdivided into weekly undulating periodization, which involves changes between high-volume low-relative load training and low-volume high-relative load training on a week-by-week basis within a single month, and daily undulating periodization, which involves changes between high-volume low-relative load training and low-volume high-relative load training on a day-by-day basis within a single week. Daily undulating periodization is much more commonly used and studied than weekly undulating periodization. Despite the common use by coaches of most if not all of these periodization methods, they have rarely been compared for enhancing gains in strength and size during resistance-training and where they have been compared they are rarely compared against a nonperiodized control group. Thus, it is difcult to be confident about the ability of the different periodization methods for improving gains in muscular strength and size.
What did the researchers do? This researchers wanted to investigate the effects of different periodization methods during a 6-week period of resistance-training on increases in muscular strength and
size in 37 recreationally-active male physical education students who regularly played sports such as soccer, volleyball, and basketball but who were not resistancetrained. Muscular strength was assessed by reference to 1RM squat in a Smith machine. Muscular size was assessed by reference to quadriceps muscle cross-sectional area measured by magnetic resonance imaging (MRI) at baseline and 48 hours after the last training session. The resistancetraining programs comprised two exercises, Smith machine squats and machine knee extensions. In each program, a 2minute inter-set rest was used and a 3-minute rest was taken between exercises. Both exercises were performed with constant speed, 2-second eccentric and 2-second concentric phases and through a 90-degree range of motion at the knee joint. The subjects were allocated into nonperiodized, traditional periodization, and daily undulatingperiodization groups, who all performed the same volume of training over the whole period. While the exact type of traditional periodization was not specified, it appears to have been of a block format rather than a linear format.
What happened? Muscular strength gains The researchers noted that 1RM squat strength increased significantly only in the non-periodized group (by 17.0%) and in the daily undulating periodization group (by 12.9%) but not in the traditional periodization group. However, their chart showed that the traditional periodization group also significantly increased 1RM squat strength, albeit to a slightly lesser extent (by 7.7%). Muscular hypertrophy The researchers found that muscular size increased significantly and similarly in all of the training groups. The non-periodized group increased by 5.1%, the traditional group by 4.6%, and the daily undulating group by 5.2%.
What did the researchers conclude? The researchers concluded that in volume-matched resistance-training programs, there is no difference between periodized and non-periodized training methods (whether daily undulating or block periodization) over short periods of time for increasing muscular size. However, for increasing muscular strength, a daily-undulating periodized program may be optimal.
Limitations The study was limited by the short duration of the trial, which was only 6 weeks. A longer period of time may have allowed more substantial differences to emerge between the groups and allow the benefits of periodization, which include the use of variety to avoid staleness, to become more clear. Additionally, the study was limited by not using resistance-trained subjects and therefore the gains in strength and size may have been primarily a function of the subjects rather than of the programs themselves.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 11
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
The effects of tapering on power-force-velocity profiling and jump performance in professional rugby league players, by De Lacey, Brughelli, McGuigan, Hansen, Samozino, and Morin, in Journal of Strength and Conditioning Research Publish Ahead of Print
Background Rugby league is a popular team sport involving high-speed running and collisions. In addition, players complete a large amount of low intensity activity (i.e. walking and jogging) during any given match. Therefore, the qualities required for high-level performance in rugby league include strength, power, muscular size, sprint running ability, and endurance. Generally, professional rugby league players play a match every 5 – 10 days in-season. This allows time to recover from the previous game, train, and prepare for the following game. The playing year in professional rugby league is divided into two halves, a 6-month in-season (plus 1-month period of play-offs if applicable) and an off-season. While the schedule in-season does not lend itself to long tapers, there are occasions where tapering is possible, beneficial and desirable in order to maximize performance. Tapering is a programmed reduction in training volume in order to maximize performance at a specific event taking place at a specific time. All of the mechanisms by which tapering exerts beneficial effects are not well understood. Some studies have indicated that in addition to allowing athletes to recover from accumulated fatigue, tapering may also have certain beneficial effects on muscle fiber type and muscle architecture. However, such changes require further investigation as the available studies in this area are few and far between. Nevertheless, it is generally accepted that tapering is effective largely because of the principle that fatigue masks fitness. Thus, athletes performing heavy training loads may not be able to demonstrate their full potential because of accumulated fatigue. A taper is designed to reveal the performance gains that have been achieved through training without allowing any detraining to occur. Thus, tapers often retain high-intensity elements but dramatically reduce training volume. Additionally, tapers can have different structures. For example, one common way to differentiate between tapers is whether they are structured with a linear reduction in volume or an exponential reduction. Despite their widespread use in many sports, however, tapers have not been widely studied and it is unclear whether tapers of the same duration and structure have the same effects on all performance variables, for example across the force-velocity spectrum.
What did the researchers do? The researchers wanted to investigate the effects of a preseason taper on power-velocity and force-velocity profiles and jump performance in 7 professional National Rugby League players. The researchers took measurements using a force plate while the subjects performed concentric squat
jumps using ascending loads of 25, 50, 75, 100% of bodyweight before and after a 21-day taper prior to the start of the in-season. The researchers used these data to calculate maximum possible force production, power output, and velocity capability in each of the subjects, as well as the force-velocity relationship. As in many tapers, the volume of resistance-training was reduced while relative loading remained high and conditioning was not altered. During the off-season, resistance-training was performed 3 – 4 times a week averaging for 60 minutes per session, while field-based sessions were performed 4 times per week for 60 minutes per session. In the taper, resistance-training was reduced to 1 session per week of 45 minutes and field sessions remained at pre-taper levels. The off-season training program was structured in a traditional block periodization model. In the first 7-week block, the athletes aimed to create increases in muscular size, performing higher numbers of repetitions (6 – 15) at moderate loads (65 – 83% of 1RM). In the second 6-week block, the athletes aimed to improve strength, using moderate repetitions (3 – 6) with heavy loads (80 – 95% of 1RM). The final block comprised the 3-week taper, which was aimed at maintaining strength and power gains, with low-tomoderate repetitions (2 – 6) and heavy loads (82 – 90% of 1RM).
What happened? Jumping performances The researchers found that from pre- to post-taper, loaded jumping heights at each load increased with moderate effect sizes. The size of the improvement was similar for each load. Calculated changes in force-velocity The researchers found that maximum force appeared to display only a small increase. There did not appear to be any meaningful improvements in either maximum velocity or in the slope of the force-velocity curve. Nevertheless, there was a moderate increase in maximum power output.
What did the researchers conclude? The researchers concluded that a 21-day taper involving an immediate reduction from 3 – 4 days of resistance-training per week to a single day of resistance-training per week was effective for increasing maximal power output and loaded jump height performance in professional rugby league players.
Limitations The study was limited in that the researchers did not compare different structures of taper, such as a step-wise reduction in the number of training sessions per week. Additionally, the study was limited in that the researchers did not test maximal strength or changes in muscular size.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 12
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
+ 9 MORE STUDIES IN THIS SECTION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 13
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
2. BIOMECHANICS AND MOTOR CONTROL
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 14
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Muscle activation during push-ups with different suspension training systems, by Calatayud, Borreani, Colado, Martiﾌ］, Rogers, Behm and Andersen, in Journal of Sports Science and Medicine, 2014
Background Unstable surface training is a relatively-new training modality that was originally introduced in order to provide already-trained individuals with a new and challenging modality that would lead to further improvements in muscular performance. However, since its introduction, it has been challenged on the basis that the loads that must be used in many unstable surface exercises are too low to produce adaptations. Nevertheless, a small number of specific exercises have been found to produce high levels of electromyographic (EMG) activity in prime mover muscles, such as the glute bridge with suspended feet, which involves much greater hamstrings EMG activity than the standard glute bridge. Additionally, many unstable surface exercises involve greater core muscle activity than their stable equivalents. Unstable surface training can be performed using various different devices, including Swiss balls, BOSU balls, and rocker boards, but suspension training may be the most flexible of all of these because it can most easily be used for both upper- and lower-body exercises. Common suspension devices include the TRX system but also, traditionally, gymnastic rings. Indeed, the push-up can be performed using gymnastic rings to make it an unstable surface exercise. However, its use in this respect has not previously been investigated.
What did the researchers do? The researchers wanted to compare the EMG activity of the prime mover muscles (the pectoralis major, triceps brachii and anterior deltoid), of synergists (the upper trapezius) and of the lumbopelvic musculature (the rectus femoris, rectus abdominis, and lumbar erector spinae) during pushups with and without suspension devices to create instability. They also wanted to compare the effects of different suspension devices, with one anchor, with two anchors, and with one anchor and a pulley system. The one anchor system was created using a TRX device, the oneanchor with a pulley was created using an AirFit Trainer Pro, and the two-anchor system was created using a Jungle Gym XT. For subjects, the researchers recruited 29 young male university students who performed 3 push-ups in each of the 4 different suspension systems, as well as on the floor in the standard push-up position. Thus, it is noted that the researchers did not normalize the relative loading used in each of the different push-up conditions by calculating a maximum effort for each condition. However, the researchers did normalize the EMG activity to a maximum voluntary isometric contraction (MVIC) for each of the muscles that were analyzed.
What happened? The researchers found significant differences between at least two of the tested conditions for all of the muscles. For recruiting the triceps brachii and the upper trapezius, the most effective exercises were the suspension devices with one anchor, while the floor push-up was the least effective. For recruiting the anterior deltoid, the reverse was the case, with the single-anchor suspension devices displaying lowest levels of EMG activity and the floor push-up displaying the most. For the pectoralis major, the two-anchor suspension device was better than all other options. For the rectus abdominis, all suspension device options were better than the floor but there was little difference between the suspension devices.
What did the researchers conclude? The researchers concluded that using a suspension system is effective for increasing the levels of rectus abdominis EMG activity during the push-up, if this is desirable. Additionally, there seem to be important differences in the muscle activity of the prime movers between the different push-up variations, with the floor push-up being most effective for the anterior deltoid, a two-anchor suspension device being best for the pectoralis major, and the singleanchor suspension devices being best for the triceps brachii. Thus, it may be optimal to use a variety of different suspension options during the push-up for taxing all of the prime movers.
Limitations The study was limited in that the same relative load was not used in each exercise. Therefore, the differences in muscle activity could have arisen because certain of the exercises were much harder to perform.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 15
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
The effects of push-ups with the trunk flexed on the shoulder and trunk muscles, by Kang, Jung, Nam, Shin, and Yoo, in Journal of Physical Therapy Science, 2014
Background The push-up is a classic, closed-kinetic chain, upper-body exercise for strengthening the pectoralis major, triceps brachii, and anterior deltoid musculature. As such, it has been investigated in numerous studies and several of its variations have been compared, including the effects of altering hand and wrist position, the effects of placing the palms different distances apart, the effects of changing the height of the legs, and the effects of performing push-ups on unstable surfaces. However, no previous study has investigated the effects of changing trunk flexion angle. It is possible that this could have effects on both the trunk and prime mover muscle activity.
What did the researchers do? The researchers wanted to compare the muscle activity of the shoulder and trunk muscles in two push-up positions: standard push-ups and push-ups with 30 degrees of trunk flexion. By flexing the trunk, this position alters the angle at which the prime movers must push against the ground and also has an effect on the amount of work the core muscles must do in order to stabilize the trunk. For subjects, the researchers recruited 15 young adult males. They recorded the electromyographic (EMG) activity of the clavicular and sternocostal portions of the pectoralis major, the serratus anterior, and the rectus abdominis during push-ups under the two conditions.
What did the researchers conclude? The researchers concluded that slight variations on the same exercises can lead to selective activation of different parts of the same muscle. It is noteworthy that different push-up variations caused preferential recruitment of a specific part of the pectoralis major, as this has important ramifications for bodybuilders. Similarly, the fact that the serratus anterior is more active during the flexed-trunk push-up variation is also important, as the serratus anterior is a key muscle that is involved in shoulder stability. Programs that are used to develop shoulder stability can therefore use this push-up variation to good effect.
Limitations The study was greatly limited in that it did not record the muscle activity in the anterior deltoid and triceps brachii. It would have been very useful to know which of these variations led to superior activity in these other prime movers. Additionally, the study was limited in that the same relative load was not used in each exercise.
What happened? Differences in prime mover muscle activity The researchers found that the EMG activity of the sternocostal part of the pectoralis major was significantly greater in the standard push-up position than in the trunk flexed position but the reverse was the case for the clavicular portion. However, overall, the EMG activity of the clavicular head appeared to be greater than that of the sternocostal head in both variations. Differences in scapular stabilizer muscle activity The researchers found that the EMG activity of the serratus anterior was significantly greater in the flexed position than in the standard position. Differences in trunk muscle activity The researchers found that the EMG activity of the rectus abdominis was significantly greater in the standard push-up position than in the trunk flexed position. However, the EMG activity of this muscle was relatively low compared to the activity of the prime movers (15 – 20% compared to 55 – 84%).
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 16
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Neuromuscular response differences to power vs. strength back squat exercise in elite athletes, by Brandon, Howatson, Strachan, and Hunter, in Scandinavian Journal of Medicine & Science in Sports, 2014
Background Elite athletes typically perform resistance-training with a range of loads, in order to develop the ability to produce force at different points on the force-velocity curve. Indeed, several studies have found that force is enhanced most at the velocity used during training. Additionally, the literature is clear that heavier loads are more beneficial for maximal strength gains compared to lighter loads. However, whether there is a single load that can maximize power outputs across a range of velocities more than others is unclear from the available long-term training evidence. It is therefore unclear whether performing non-ballistic resistance-training with light or moderate loads is superior for power development to heavy loads. While long-term trials are the gold-standard for assessing the changes in a desired outcome measure like muscular power, acute trials are also helpful where they provide indications of factors that need to be investigated. While most acute trials have focused on an assessment of power output, this may not be the most useful measurement when considering the longterm adaptations that arise from the workout. Therefore, measurements of fatigue might be useful to understand as well. While electromyography (EMG) can be used to understand aspects of fatigue, the exact nature of the fatigue is not easy to ascertain using this technique. Muscular fatigue is subdivided into two aspects, central and peripheral. Central fatigue refers to processes that occur proximally to the neuromuscular junction, while peripheral fatigue refers to processes that occur distally to the neuromuscular junction. It is most straightorward to think of central fatigue as occurring spinally or supra-spinally and peripheral fatigue as occurring within the muscle itself. The central activation ratio (CAR) and evoked peak twitch force (PTF) can separate out the central fatigue (i.e. motor neuron firing) and peripheral fatigue (e.g. excitationcontraction coupling) elements of overall fatigue. PTF is typically calculated as the peak change in force during passively stimulated muscular contractions (i.e. the muscle is relaxed prior to the electrical stimulus) from the prestimulated values recorded in a dynamometer. CAR is typically calculated in a similar way but is different in two key respects. Firstly, the electrical stimulation of the muscle is performed while the muscle is contracting and not relaxed. Secondly, it is calculated as the ratio of peak voluntary force (prior to the stimulation) to the peak electrically stimulated force and not as the change. These measurements are useful in this context, as it is possible that heavy, moderate and light loads lifted with maximal velocity could lead to different components of overall fatigue and therefore give rise to differing responses.
What did the researchers do? The researchers wanted to explore the nature of the fatigue responses in 10 elite track and field athletes to maximal explosive back squats with heavy, moderate, and light loads. The subjects performed 10 sets of 5 maximal back squat repetitions. Before and after each trial, the researchers measured knee extension maximal isometric voluntary contraction (MIVC), EMG activity of the knee extensors, rate of force development (RFD), PTF and CAR using a dynamometer, surface electrodes and electrical stimulation pads. During the trials, the researchers also measured kinematic variables by using a linear transducer on the barbell and an electrogoniometer to capture knee angle.
What happened? Measurements during the squats The researchers found that power output and impulse increased in a load-specific manner during the squats from light > moderate > heavy. In contrast, for repetition duration, the order was heavy > moderate > light. The researchers found that power output declined throughout the test only in the heavy group. Measurements afer the squats The researchers reported that each of MIVC and RFD were significantly altered after each loading condition. They found that PTF (PTF = the measurement of peripheral fatigue) was only altered after the heavy and moderate conditions. In each case, the changes were load-specific in the order heavy > moderate > light. CAR did not alter as a result of any of the tests.
What did the researchers conclude? The researchers found that the lightest load produced the greatest power output and impulse but the shortest repetition duration during the explosive squats. They found that peripheral fatigue occurred during the heavy and moderate conditions but not after the light loading condition. They noted that power output declined during the performance of the squats only in the heavy group. On this basis, they suggest that moderate-load squats might be best for power development.
Limitations The study was limited in that it was not volume-matched and when using heavy loads it would normally be expected to use a smaller number of sets in order to maintain a similar volume to the conditions using light or moderate loads. Moreover, the study was limited in that it was an acute investigation and we therefore do not know whether training with moderate loads would lead to superior gains in power output over a long-term period.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 17
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
+ 12 MORE STUDIES IN THIS SECTION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 18
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
3. ANATOMY, PHYSIOLOGY AND NUTRITION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 19
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
A systematic review and meta-analysis examining the effect of eating rate on energy intake and hunger, by Robinson, Almiron-Roig, Rutters, De Graaf, Forde, Smith, Nolan, and Jebb, in American Journal of Clinical Nutrition 2014
Background Previous observational studies have noted an association between being overweight or obese and a faster speed of eating. Thus, it is possible that eating speed may be one reason why some individuals become overweight or obese. Indeed, some clinical interventions have even made recommendations that overweight or obese individuals eat more slowly. However, differences in eating rate have not been consistently observed between overweight or obese individuals and normal weight individuals in a controlled environment. Therefore, a meta-analysis of the available results is required in order to identify the prevailing trend.
What did the reviewers do? The reviewers performed a systematic review and metaanalysis of the effect of eating rate on energy intake during experiments in controlled environments that manipulated eating rate and observed its effects on energy intake, selfreported hunger, or both. The reviewers identified 3 different types of study. Type 1 studies manipulated eating rate and measured the resulting energy intake. Type 2 studies were the same as type 1 studies but also measured self-reported hunger. Type 3 studies manipulated eating rate while keeping energy intake constant but then measured self-reported hunger at a later time. The reviewers only incorporated studies with human subjects without a clinically defined eating disorder.
Type 3: self-reported hunger afer consuming a fixed meal The reviewers observed 4 studies that investigated selfreported hunger after eating a fixed meal at either a fast or slow rate. The final time point that was measured for hunger varied between the studies and was 180 minutes post-meal for 2 studies and 210 minutes post-meal for 2 studies. However, the reviewers did not detect any significant effect of eating rate on post-meal hunger.
What did the reviewers conclude? The reviewers concluded that slower eating rates lead to a significant reduction in energy intake but does not appear to alter self-reported hunger either immediately post-meal or 2 – 3 hours post-meal. The reviewers therefore concluded that reducing eating rate may be an effective behavioral strategy for decreasing energy intake to prevent or treat obesity.
Limitations The review was limited in that a considerable degree of heterogeneity that was observed in the results, which was not accounted for. Why there was such a difference in findings between individual studies is not clear and other factors seem to be involved. Identifying these factors could open up new and useful avenues in the research into overweight and obesity.
What did the reviewers find? Studies included The reviewers reported that their initial search produced 733 results but after screening the titles and abstracts there were only 76 publications of interest. After screening fulltexts and looking through the references of these papers, the reviewers ended up with 22 studies, which were analyzed as types 1, 2 or 3 as described above. Type 1: the effect of eating rate on energy intake The reviewers noted that there were 21 studies that fell into the type 1 category. They noted that these studies together reported a significant and small-to-medium-sized effect of eating rate on energy intake. Thus, in the fast eating rate conditions, the subjects displayed a higher energy intake than those in the slow eating rate conditions. Type 2: self-reported hunger afer consuming a meal The reviewers noted that of the 21 type 1 studies, 11 also measured and reported hunger at meal completion and were therefore also classified as type 2 studies. They found that there was no significant effect of eating rate on hunger. This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 20
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study, by Wilson, Lowery, Joy, Andersen, Wilson, Stout, Duncan, Fuller, Baier, Naimo and Rathmacher, in European Journal of Applied Physiology, 2014
Background Several previous studies have found that supplementation with the leucine metabolite, beta-hydroxy-beta-methylbutyrate (HMB) during periods of chronic (long-term) resistance-training can increase gains in both muscular strength and size. However, most of the studies that have reported positive results have been performed in untrained individuals and the gains appear to be most marked during the early phase of training. Nevertheless, by investigation of the mechanisms, it is thought that HMB helps improve adaptations from resistance-training through enhanced recovery of damaged skeletal muscle tissue. Recently, HMB became available in a free acid form (HMB-FA) which is thought to lead to superior bioavailability. However, no long-term studies have been performed using this type of HMB.
What did the researchers do? The researchers explored the effects of supplementing with HMB-FA on changes in muscular strength, power, and size in 24 resistance-trained male subjects. They measured strength gains by reference to 1RM tests in the bench press, squat, and deadlift. Lean body mass was assessed using a lunar Prodigy dual-energy X-ray absorptiometry (DEXA) apparatus and muscle thickness was measured by ultrasonography of the vastus lateralis and vastus intermedius. Peak power output was measured both during a cycling Wingate test and also during a countermovement jump performed on a force platorm. In addition to these measures of strength, power and size, the researchers also explored how the supplement would affect markers of muscle damage and catabolic hormone levels during an overreaching cycle. The researchers randomly assigned the subjects to receive either 3g per day of HMB-FA or a placebo. Both supplement protocols were divided equally into 3 servings and the first serving was consumed 30 minutes pre-exercise while the other two servings were consumed with the mid-day and evening meals. The subjects trained in 3 phases. Phase 1 comprised a daily undulating periodized resistance-training program, 3 days per week (weeks 1 – 8). Phase 2 comprised an overreaching cycle in which subjects trained 5 days per week and also performed an additional day of power testing (weeks 9 – 10). Phase 3 comprised a taper (weeks 11 – 12). Compliance with the training program was 100% for all subjects who completed the study.
What happened? Muscular strength The researchers reported that the use of HMB-FA led to significantly superior gains in strength when the changes in bench press, squat, and deadlift 1RM were all combined over the 12-week training (77.1 ± 18.4 vs. 25.3 ± 22.0 kg) in comparison with the placebo group. The individual lift improvements in the HMB and placebo groups were 25% and 5% for the squat, 12% and 3% for the bench press, 16% and 9% for the deadlift, and 18% and 6% for total strength. These differences were also significant. Muscular power output The researchers reported that the use of HMB-FA led to significantly superior gains in vertical jump power (991 ± 168 vs. 630 ± 167 W) in comparison with the placebo group. The percentage improvement was also significant, at 19% compared to 12%. The increase in cycling Wingate test peak power was also significantly greater in the supplement group, by 18% compared to 12%. Muscular size The researchers reported that the use of HMB-FA led to significantly superior increases in lean body mass (7.4 ± 4.2 vs. 2.1 ± 6.1 kg) in comparison with the placebo group. The increase in quadriceps muscle thickness in the HMB-FA group was also significantly greater. Markers of muscle damage and catabolic hormones During the overreaching cycle, the researchers reported that HMB-FA led to significantly smaller increases in creatine kinase levels (−6 ± 91 vs. 277 ± 229 IU/l) as well as cortisol (−0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl) in comparison with the placebo.
What did the researchers conclude? The researchers concluded that HMB-FA leads to superior gains in muscular strength, power and size when administered in conjunction with long-term resistancetraining, and may also have beneficial effects during periods of overreaching by reducing levels of creatine kinase (a marker of muscle damage) and of cortisol (a catabolic hormone) but whether such indicators are reflective of any reduced risk of overtraining is unclear.
Limitations The study was limited in that it is unclear whether the markers of overreaching that were affected by the supplement relate in any meaningful way to inferior recovery, the risk of non-functional overreaching, or the risk of overtraining. The study was also limited in that the research was funded in part through a grant from Metabolic Technologies Inc. and some of the researchers involved in the paper were employees of that business.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 21
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation, and other metabolic risk factors – a randomized controlled trial, by JuanolaFalgarona, Salas-Salvado, Ibarrola-Jurado, Rabassa-Soler, DiĚ az-Lopez, Guasch-Ferre, Hernandez-Alonso, Balanza, and Bullo, in American Journal of Clinical Nutrition, 2014
Background Despite significant interventions in relation to public health, obesity is a major concern and has been associated with an increased risk of various non-communicable diseases, including hypertension, dyslipidemia, type II diabetes cardiovascular disease, and cancer. Public health strategy has involved both exercise and dietary interventions to reduce obesity and overweight. Dietary interventions have traditionally focused on two main issues: macronutrient profile and total energy intake. A standard recommendation for a dietary intervention to reduce obesity or overweight is to consume an energy deficit along with a macronutrient ratio comprising >50% of calories from carbohydrates, <30% of calories from fat, and the remaining proportion from protein. However, there is no consensus in the literature regarding the optimal macronutrient breakdown. In addition, this focus on increasing carbohydrates and reducing fats and largely ignoring protein is now clearly outdated, as there is growing evidence that increased protein consumption during periods of weight loss leads to significantly greater lean mass retention and consequently superior losses in fat mass. Nevertheless, there is still interest in comparing dietary interventions focusing on the relative quantities of carbohydrate and fat. In this regard, it is interesting that a recent meta-analysis of randomized controlled clinical trials found no differences in respect of weight loss between low-carbohydrate nonâ&#x20AC;&#x201C;energyrestricted diets with energy-restricted low-fat diets. Moreover, it was concluded that the low-carbohydrate diets led to superior improvements in lipid profiles. In contrast, a meta-analysis of epidemiological studies found that low-carbohydrate diets were associated with an increased risk of all-cause but not cardiovascular mortality. Thus, there appear to be other factors involved. Some researchers have suggested that the concept of glycemic index (GI) should be used to further define the type of carbohydrates that are consumed, with some being described as high-GI and others as low-GI. In this context, it has been suggested that low-GI diets may be superior to high-GI diets for weight loss. However, to date there is little evidence to support any difference in effects of either highGI or low-GI diets on conditions of overweight or obesity.
What did the researchers do? The researchers wanted to investigate the effects of two different moderate-carbohydrate diets in comparison with a low-fat diet on weight loss and satiety, inflammation, and other metabolic risk markers in a 6-month, randomized,
parallel, controlled clinical trial in 122 overweight and obese adults. The two moderate-carbohydrate diets differed in respect of their GI, in that one involved the consumption of low-GI foods and the other involved the consumption of high-GI foods. All diets contained 18% protein, the low-fat diet contained 52% of calories from carbohydrates and 30% from fat, the low-GI and high-GI diets both contained 42% of calories from carbohydrates and 40% of calories from fat. Thus, it is important to note that there was no low-carbohydrate diet group in this study. The researchers randomly assigned the subjects to one of these three isocaloric, energy-restricted diets for the duration of the intervention. Before and after the intervention, the researchers measured body mass index (BMI) as their primary marker of weight loss, as well as various health measures, including fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of beta cell function (HOMA-B), hunger, satiety, lipid profiles, and other inflammatory and metabolic risk markers.
What happened? Changes in BMI The researchers found that reductions in BMI were greater in the low-GI group than in the low-fat group but there was no difference in the change in BMI between the high-GI and low-fat groups. Changes in health markers The researchers found that the decrease in fasting insulin, HOMA-IR, and HOMA-B were all significantly greater in the low-GI group than in the low-fat group. There were no differences between groups in respect of hunger, satiety, lipid profiles, or other inflammatory and metabolic risk markers.
What did the researchers conclude? The researchers concluded that when performed in conditions of energy-restriction, a moderate-carbohydrate diet (40% fat, 42% carbohydrates) may be more effective than a high-GI diet with identical macronutrient profile and a low-fat diet (30% fat, 52% carbohydrates) at reducing body mass index. They also noted that it may also be superior for controlling glucose and insulin metabolism. Whether a low-carbohydrate diet or a high-protein diet would have outperformed any of these options, however, is unclear.
Limitations The study was limited in that it only compared two relatively moderate-to-high carbohydrate diets by macronutrient content and did not compare higher protein diets or low-carbohydrate diets in the same conditions. Additionally, BMI was used instead of actual changes in fat mass and therefore either muscle mass or water content changes could have led to discrepancies.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 22
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
+ 7 MORE STUDIES IN THIS SECTION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 23
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
4. PHYSICAL THERAPY AND REHABILITATION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 24
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Roller massager improves range of motion of plantar flexor muscles without subsequent decreases in force parameters, by Halperin, Aboodarda, Button, Andersen, and Behm, in The International Journal of Sports Physical Therapy, 2014
Background Myofascial release is a form of manual therapy that is increasingly becoming used by physiotherapists and manual therapists for the treatment of various conditions, including musculoskeletal pain. Myofascial release involves the use of hands, knuckles or elbows or other tools to exert pressure on the muscles and fascia of the body. It is thought that by exerting pressure on the muscles and fascia, areas of hardened muscle and/or fascia can be encouraged to relax. A number of different mechanisms have been proposed to explain how this process might occur but there is currently no strong consensus in favor of any single mechanism. Selfmyofascial release is a subset of myofascial release techniques in which pressure is applied by the individual to themselves rather than by a therapist. Foam rolling is one of the most common types of self-myofascial release in use at present. A limited number of studies have found that foam rolling is effective for increasing flexibility, as measured by joint range of motion (ROM) in acute trials. Moreover, studies have also suggested that foam rolling does not lead to acute reductions in performance measures, such as maximal strength, power output, or jumping ability, as is frequently found following static stretching interventions. Thus, it is possible that foam rolling could be a superior method of improving flexibility prior to sports performance or training, where this is required.
Ankle plantar flexion torque The researchers found that neither roller massage nor static stretching significantly altered plantar flexion torque at 1 and 10 minutes post-intervention but there was a significant difference between interventions, as there was a non-significant trend for torque to increase in the roller massage condition and a non-significant trend for torque to decrease in the static stretching condition.
What did the researchers conclude? The researchers concluded that while both interventions improved flexibility, self-massage with a roller massager led to small improvements in force production relative to the static stretching condition at 10 minutes post-intervention.
Limitations The study was limited in that the researchers did not also measure dynamic performance such as by way of the countermovement jump, which is more commonly used to assess the effects of static stretching or other acute interventions on sports performance.
What did the researchers do? The researchers assessed the effects of static stretching and roller massage on ankle dorsiflexion ROM and plantar flexion torque in 90 degrees of knee flexion and neutral ankle position in 14 recreationally-trained male subjects. The ankle dorsiflexion ROM of the subjects was tested using an in-line lunge test against a wall on two separate occasions in a randomized cross-over design, pre- and posteither the static stretching or roller massage interventions. The post-intervention measurement was taken at both 1 and 10 minutes after the intervention was performed. Both interventions were performed for 3 sets of 30 seconds with 10 seconds of inter-set rest.
What happened? Flexibility The researchers found that both roller massage (3.6 â&#x20AC;&#x201C; 4.4%) and static stretching (5.0 â&#x20AC;&#x201C; 5.4%) significantly increased ankle dorsiflexion ROM both at 1 and 10 minutes postintervention but there was no significant difference between interventions.
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 25
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
Specific and cross over effects of massage for muscle soreness – randomized controlled trial, by Jay, Sundstrup, Søndergaard, Behm, Brandt, Særvoll, Jakobsen, and Andersen, in The International Journal of Sports Physical Therapy, 2014
Background Delayed onset muscle soreness (DOMS) is frequently experienced by athletes and recreational trainees when exposed to either novel resistance-training workouts or a large volume of eccentric muscle actions. Symptoms include soreness, tenderness upon palpation, and stiffness during movement. DOMS appears to occur reliably between 12 – 24 hours post-workout, with soreness peaking around 48 hours post-workout. There is a lack of consensus regarding the underlying mechanisms that cause DOMS. Some researchers have considered DOMS to be caused entirely by exercise-induced muscle damage (EIMD). EIMD is similarly characterized by muscle soreness, muscle swelling, an increase in intramuscular protein and passive muscle tension, and also involves a reduction in muscular strength and range-of-motion. In this model, EIMD causes various disruptive changes, including sarcomere damage, calcium accumulation, protein degradation, and increased osmotic pressure. These changes lead to the sensitization of nociceptors and other pain receptors, which leads to the sensation of DOMS being experienced. A number of different interventions have been tested for reducing both EIMD and DOMS. There is some evidence to support the use of massage and limited evidence to support the use of self-myofascial release with a foam roller. The mechanisms by which massage or self-massage might be effective for reducing DOMS are not well-understood and various possibilities are currently being explored by researchers. One possibility is that the mechanism occurs via central adaptation of pain perception. Given that a cross-over effect between limbs occurs routinely in acute trials for fatigue and in chronic trials for training, it might be expected that an acute effect of pain perception might occur in response to self-massage if the mechanism by which it exerts part or all of its effects occur through central adaption.
soreness in the hamstring muscles of both legs using a visual analogue scale, the researchers tested their pressure pain threshold through palpation, and the researchers also tested their hamstring flexibility by a one-legged sit-andreach test. At this visit, the subjects in the control group experienced no further intervention but the subjects in the massage group received foam rolling treatment on one leg only. Measurements of soreness, pressure pain threshold and flexibility were taken before and at 0, 10, 30 and 60 minutes post-foam rolling treatment.
What happened? Effect of foam rolling The researchers reported that the massage group displayed significantly reduced soreness and greater pressure pain threshold compared with the control group at 0, 10 and 30 minutes post-massage. Additionally, flexibility, as measured by the sit-and-reach test, was greater at 0 minutes postmassage but the effects were lost at 10 minutes. Cross-over effect The researchers reported that at the 10 minute point postmassage there was a significant reduction in soreness of the non-massaged limb but this effect was lost by the 30minute point.
What did the researchers conclude? The researchers concluded that massage using a foam rolling device reduces muscle soreness and increases pressure pain threshold at 48 hours post-workout. They concluded that there was also a tendency towards a soreness-reducing effect in the contralateral limb which may indicate the existence of a cross-over effect through central pathways.
Limitations The study was limited in that the self-massage technique was not compared with any other modality for reducing muscle soreness. Additionally, the study was limited in that there was no test of performance. It would have been interesting to see whether the self-massage affected maximal force production or jumping ability.
What did the researchers do? The researchers investigated the acute effect of massage with a Thera-band roller massager on hamstring muscle soreness directly in one leg and also the potential crossover effect to the non-massaged leg in 22 healthy but untrained subjects. The subjects were randomly allocated into a massage group and a control group. On one day, all subjects performed 10 sets of 10 repetitions of stiff-legged deadlifts with a kettlebell, separated by 30 seconds of rest with a tempo of 1 – 2 seconds for the concentric and eccentric phases of each repetition. Around 48 hours postworkout, the subjects returned and rated the level of This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 26
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee, by Barcellona, Morrissey, Milligan, Clinton, and Amis, in Knee Surgery, Sports Traumatology, Arthroscopy, 2014
Background The anterior cruciate ligament (ACL) is often injured in sport and is the main passive structure that prevents anterior translation of the tibia at the knee. ACL loading has been measured during various different movements and it has been reported that during open kinetic chain knee extension exercise, the size of the ACL loading is directly related to the absolute load used in the exercise. Additionally, long-term studies of ACL rehabilitation patients have found that where larger loads are achieved over a progressive resistance-training program involving open kinetic chain knee extension exercise, this leads to a reduction in anterior knee laxity. A reduction in anterior knee laxity could be beneficial for decreasing the risk of ACL injury long-term in either individuals who have already incurred an ACL injury or in individuals with genetic predisposition to greater knee joint laxity, which places them at increased risk of ACL rupture.
Physical function changes The researchers found no significant improvements in single-leg hop with single-leg landing or with two-leg landing in any of the groups and there were no significant differences between groups.
What did the researchers conclude? The researchers concluded that low relative-load open kinetic chain knee extension exercise led to a reduction in anterior knee laxity in an ACL-injured knee compared to either a standard program or a standard program plus high relative-load open kinetic chain knee extension exercise.
Limitations The study was limited in that the researchers only measured two tests of physical function that are not strongly associated with strength of the quadriceps. Tests of knee or leg extension strength, whether open or closed chain, might have been better indicators of the functional success of the interventions.
What did the researchers do? The researchers investigated the effect of different relative loads during open kinetic chain knee extension resistancetraining programs on anterior knee laxity and function in 58 subjects with ACL injuries. The subjects were randomized to 1 of 3 training groups for a 12-week intervention. One group performed a standard rehabilitation program. A lowrelative load group and a high-relative load group both performed the same program but also performed seated open kinetic chain knee extension resistance-training for 2 sets of 20RM or 20 sets of 2RM, respectively. Before and after the 12-week intervention, the researchers measured anterior knee laxity as well as physical function and knee joint range-of-motion (ROM). The measurement of anterior knee laxity was performed using a knee joint arthrometer. The two physical function tests comprised a single-leg horizontal hop with two-leg landing and a single-leg horizontal hop with single-leg landing.
What happened? Anterior knee laxity The researchers found that the low-relative load group displayed a reduction in anterior knee laxity between preand post-testing compared to both the standard program and to the high-relative load group. The anterior knee laxity decreased by around 5mm in the low relative load group but remained broadly the same in the other two groups. Knee joint ROM The researchers found a significant improvement in knee joint flexion ROM but not for knee joint extension ROM. There was no significant difference between groups. This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 27
Strength and Conditioning Research
STRENGTH & CONDITIONING RESEARCH
TASTER EDITION (BASED ON AUGUST 2014)
+ 10 MORE STUDIES IN THIS SECTION
This document is copyright Strength and Conditioning Research Limited, 2014. Subscribe at the website HERE!
Page 28