The physiological and performance effects of lower-body compression garments in high-performance cyc by SKINS

THE PHYSIOLOGICAL AND PERFORMANCE EFFECTS OF LOWERLOWER-BODY COMPRESSION GARMENTS IN HIGHHIGH- PERFORMANCE CYCLISTS

Ben Dascombe, BHMSc (Hons) MAAESS1 Aaron Scanlan, BHMSc1 Mark Osbourne, BHMSc (Hons)2 Brendan Humphries, PhD1 Peter Reaburn, PhD1

School of Health and Human Performance,, Central Queensland University 2

Centre of Excellence, Queensland Academy of Sport

Report Submitted: 4 December 2006

This research was funded by the Queensland Academy of Sport and Skinsâ&#x201E;˘ Compression Garments

TABLE OF CONTENTS INTRODUCTION Development of the Problem ........................................................................4 Purpose of the Study ....................................................................................6 Limitations of the Study .................................................................................7 Delimitations of the Study .............................................................................8 Summary ......................................................................................................9

METHODS Subjects ......................................................................................................10 Compression Garments ..............................................................................10 Exercise Testing .........................................................................................11 Incremental Test ................................................................................ 12 One-Hour Time Trial .......................................................................... 12 Physiology Measures ..................................................................................13 Blood Lactate ..................................................................................... 13 Heart Rate ......................................................................................... 14 Expired Gas Analysis ......................................................................... 14 Near-Infrared Spectroscopy ............................................................... 15 Statistical Analysis ......................................................................................17

RESULTS Incremental Tests .......................................................................................19 Power Output ..................................................................................... 20 Blood Lactate ..................................................................................... 20 Anaerobic Threshold .......................................................................... 21 2

Oxygen Consumption ........................................................................ 22 Muscle Oxygenation .......................................................................... 22 Blood Lactate Clearance .................................................................... 23 One Hour Time-Trials .................................................................................24 Power Output ............................................................................. 24 Work .......................................................................................... 25 Blood Lactate ............................................................................. 27 Oxygen Consumption ................................................................ 27 Muscle Oxygenation .................................................................. 28

DISCUSSION Effects of LBCG during the incremental test ...............................................29 Effects of LBCG on 1HTT performance ......................................................33 Limitations ...................................................................................................35 Summary ....................................................................................................36

SUMMARY AND FUTURE RECOMMENDATIONS...........................................38

FUTURE RECOMMENDATIONS ......................................................................40

REFERENCES ..................................................................................................42

CHAPTER 1

INTRODUCTION Development of the Problem In todayâ&#x20AC;&#x2122;s competitive sporting environment, athletic equipment is continually evolving to improve sport and exercise performance. The wearing of compression garments (CG) during training and competition has become increasingly popular in both recreational and elite athletes (Wallace et al. 2005).

Within clinical investigations, CG have been employed as an effective preventative and treatment tool for several medical conditions, including venous thrombosis (Agnelli, 2004; Ramzi & Leeper, 2004), venous ulcers (Fletcher et al. 1997; Simon et al. 2004) and lymphedema (Yasuhara et al. 1996; Brennan & Miller, 1998; Cohen et al. 2001; Oâ&#x20AC;&#x2122;Brien et al. 2005). Wearing CG primarily benefits clinical patients by improving venous circulation (Simon et al. 2004), reducing blood pooling (Morris et al. 2004) and enhancing fluid transfer within the lymphatic system (Puleo & Luh, 1995). Whilst these mechanisms support wearing CG to treat clinical conditions has been readily examined (Belcaro et al. 1990; Puleo & Luh, 1995; Mayrovitz & Larsen, 1997; Junger et al. 2000; Moffatt, 2002; Morris et al. 2004), their efficacy on athletic performance has not been thoroughly investigated.

Previous research has suggested that wearing CG offers several athletic benefits (Berry & McMurray, 1987; Chatard, 1998; Kraemer et al. 2000; Shim et al. 2001; Doan et al. 2003; Bernhardt & Anderson, 2005). While CG manufacturers have proposed numerous performance benefits, the majority of 4

these claims remain unsupported. Existing literature has suggested that wearing CG improves thermoregulation through more efficient blood redistribution responses (Johnson, 1998; Shim et al. 2001; Charkoudian, 2003; Doan et al. 2003). Further research has suggested that wearing CG reduces the risk of soft tissue

injury

during

explosive

activity

increasing

musculotendinous

temperature and restricting limb range of motion (Shim et al. 2001; Bernhardt & Anderson, 2005). Importantly, wearing CG has also been reported to improve muscle waste removal and [BLa-] clearance following high-intensity exercise (Berry & McMurray, 1987; Chatard et al. 2004; Lambert & Chow, 2004). Therefore, despite the wearing of CG being shown to benefit several physiological parameters, any proposed performance enhancements remain unsubstantiated (Chatard, 1998; Lambert & Chow, 2004).

While wearing CG has been suggested to improve athletic performance, limited data supports these claims (Kraemer et al. 1997; Chatard, 1998; Kraemer et al. 2000; Shim et al. 2001; Doan et al. 2003). Previously wearing lower-body compression garments (LBCG) has been shown to significantly improve both vertical jumping (Kraemer et al. 2000; Shim et al. 2001) and endurance running performance (Chatard, 1998; Lambert, 2005). More recent data from Lambert (2005) observed that wearing whole-body compression garments (WBCG) . significantly improved AnT and VO2max across an incremental test to exhaustion. While these performance benefits have been reported, the responsible mechanisms have not been definitively identified and as such, several plausible hypotheses have been put forward. The majority of these hypotheses appear to be related to the circulatory benefits associated with wearing CG. These benefits have been suggested to improve the delivery and utilisation of oxygen (O2) within the compressed musculature (Doan et al. 2003; Lambert & Chow, 2004; Lambert, 5

2005). However, limited data has been put forward to support these suggestions (Agu et al. 2004).

Wearing CG has been suggested to improve the delivery and utilisation of oxygenated blood to the working muscle within and surrounding the compressed musculature (Agu et al. 2004; Lambert, 2005). These researchers suggested that this proposed increase in O2 transport and utilisation may allow greater decreases in mOxy within the compressed musculature (Agu et al. 2004). While some investigators have proposed that these circulatory improvements may benefit aerobic metabolism during exercise (Lambert, 2005), other researchers have reported that increases in O2 delivery do not necessarily facilitate greater extraction of O2 within the working muscle (Sirna et al. 1998; Grassi 2005). Therefore, given the proposed circulatory, metabolic and performance benefits of wearing CG during exercise, their application in endurance sports appears to be of great interest to athletes, coaches and sports science researchers (Chatard, 1998; Lambert & Chow, 2004).

Purpose of the Study The current study has three main purposes, including:

To examine the effects of LBCG on physiological performance measures . such as AnT and VO2max, across an incremental cycling test;

To examine the effects of LBCG on endurance cycling performance across a 1HTT in high-performance cyclists, and;

To identify any physiological mechanisms that may be related to any observed performance benefits related to the wearing of LBCG.

Limitations of the Study The following limitations apply to the current study: 1. Subject motivation Subject motivation could not be objectively controlled within the present

study,

and

subjects

were

given

standardised

verbal

encouragement during every test.

2. Subject preconceptions Subjects may have had preconceptions concerning the use of LBCG, prior to testing, and subjects were educated on the lack of data supporting or demonstrating any performance claims.

3. Compression consistency Each participant was required to wear the same LBCG during all testing sessions.

4. Representative nature of the NIRS probe The NIRS probe was placed over a standardised motor point of the vastus lateralis muscle, and changes in NIRS measures were representative of changes within the entire thigh.

5. Subject compliance Subject compliance with diet and training was unable to be completely controlled throughout the duration of the testing period. Subjects were provided set dietary and exercise guidelines for 48 h prior to each testing session to follow. 7

Delimitations of the Study The following delimitations apply to the current study: 1. Subject inclusion criteria Subject inclusion criteria accounted for influential factors such as age, gender and cycling training.

2. Circadian variation The times of testing were standardised for all subjects and matched as closely as possible to their regular training/competing schedules to account for circadian variances.

3. Environmental influences All testing was performed within similar environmental conditions within the same testing laboratory. All tests were completed within standardised laboratory conditions at <22 Âą 2 ÂşC and <70% relative humidity.

4. Limited subject sample size The current study was very time-demanding and limited to highperformance cyclists. As a consequence, a small number of subjects (n=12) was utilised for the present study.

5. Gender restriction of subjects Subjects recruited for the current study were restricted to males to restrict any gender or hormonal factors that may influence the results.

6. Sport restriction of subjects Subjects recruited for the current study were restricted to highperformance cyclists and triathletes currently in training.

Summary Previously, wearing CG during sport and exercise has been reported to . improve [BLa-] clearance, AnT and VO2max (Chatard et al. 2004; Lambert, 2005). It has been suggested that the use of CG increases the delivery and utilisation of O2 within working muscles (Lambert, 2005), but no research has investigated this mechanism. Furthermore, numerous researchers have proposed that wearing CG may improve endurance sport and exercise performance (Chatard, 1998; Lambert & Chow, 2004; Lambert, 2005; Ali et al. 2006), but limited existing research has reported such benefits (Chatard, 1998). The present study aims to fill a number of gaps within current research through examining the physiological and performance effects of LBCG during endurance cycling.

CHAPTER 2

METHODS Subjects Twelve male cyclists (( X ± SD) age: 20.5 ± 3.6 yr; height: 177.5 ± 4.9 cm; . body mass: 70.5 ± 7.5 kg; V O2max: 55.2 ± 6.8 mL•kg-1•min-1) volunteered to participate in the present study. All subjects were competitive cyclists completing at least 300 km of cycling per week. Prior to participation, each subject was informed of the procedures and provided their written consent. Subjects were also screened for any medical contraindications that may have excluded them from participation. All research practices were granted approval by a University Human Ethics Committee.

Compression Garments The LBCG used in the present study were unisex full-length tights (Sport Skins Classic, SkinsTM, Campbelltown, NSW) and were comprised of 76% Nylon and Meryl Microfibre, and 24% Roica Spandex. Each LBCG was custom-fit using a mathematical algorithm based on subject stature and body mass. The LBCG ran from the superior aspect of the medial malleolus of the ankle to fractionally superior to the iliac crest. The LBCG were hypercompressive, with the fabric expanding to almost 100% of body dimensions while exerting graded compression forces on the underlying tissue. The pressures exerted by the LBCG in the present study were measured using a Kikuhime pressure monitor (TT MediTrade, SorØ, Denmark). The LBCG exerted average pressures of 9.1, 14.8, 17.6 and 19.3 mmHg over the posterior gluteus maximus, medial vastus lateralis (VL), medial gastrocnemius and medial ankle, respectively (see Figure 10

1). The control condition was provided by wearing regular, loose underwear briefs (Brief Cotton, Jockey International, Victoria, Australia).

9.1 ± 1.9 mmHg

14.8 ± 2.6 mmHg

17.6 ± 3.3 mmHg

19.3 ± 3.5 mmHg

Figure 1: Compression gradient of the LBCG used in the current study ( X + SD).

Exercise Testing Prior to each testing session, subjects were instructed to maintain their regular training regime and eat a high-carbohydrate diet. Initially, subjects . completed repeat step-wise incremental tests to assess AnT and VO2max as per the methods of Craig et al. (2000). Subjects also completed repeat 1HTT to provide individual measures of endurance cycling performance. All exercise testing was performed on an electro-magnetically braked cycle ergometer (Excalibur, Lode, Groningen, The Netherlands). During testing familiarisation, each cyclist’s position was matched to their own personal bicycle configuration. 11

Subjects wore their own shoes and cleats throughout all testing occasions. Subjects were required to maintain a cadence between 90-100 RPM throughout all testing. All tests were completed within standardised laboratory conditions at 22 ± 2 ºC and <70% relative humidity. All exercise testing sessions were separated by at least 48 h, and performed at the same time of day to avoid circadian variances.

Incremental Test Subjects performed repeat step-wise incremental tests to exhaustion to . determine the effects of wearing LBCG on AnT and V O2max. Prior to each incremental test, subjects performed a warm-up protocol of 3 min at 100 W and a further 2 min at self-selected variable power output (PO). The incremental test consisted of 3 min stages, commencing at 100 W and increasing by 50 W each stage as per the methods of Craig et al. (2000). Test termination was determined using the criteria proposed by Howley and colleagues (1995), which involves the observation of any two of the following [: (1) volitional exhaustion; (2) attainment of age-predicted maximal HR (220-age); (3) Respiratory Exchange Ratio value . >1.15; or (4) plateau in VO2 (increase < 2 mL•kg-1•min-1) despite an increase in work load]. AnT was calculated using the 4 mmol•L-1 ADAPT method using the . SASI macro from the [BLa-], HR and VO2 data (South Australian Sports Institute, . Adelaide, Australia). VO2max was defined as the highest 30 s rolling average of . V O2 at the completion of the incremental test. Following completion of the incremental test, subject pedalled at 50 W at a cadence of 70 RPM in order to assess [BLa-] clearance following maximal intensity exercise.

One-Hour Time Trial Each subject also performed two randomized 1HTT on separate occasions to examine the effects of LBCG on actual cycling performance. Prior to each 1HTT, subjects undertook a 5 min warm-up at 100 W and then a further 2 min at selfselected variable PO. Each 1HTT was started at the condition-specific PO attained at each individualâ&#x20AC;&#x2122;s AnT from the repeat incremental tests. During the 1HTT, subjects were freely able to manipulate their PO using a custom-made electronic switch, which was integrated to the ergometer control box and positioned on the ergometer handlebars. Subjects were encouraged to maintain a cadence of between 90-100 RPM throughout the 1HTT, and standardised verbal encouragement was given across each test.

Throughout the 1HTT, PO, cadence and accumulative work were recorded at 1 Hz using custom-written Labview software (National Instruments, Austin, Texas, USA) on a personal computer connected to the ergometer control box. Absolute and relative ( per kg BM-1) measures of mean power, peak power and total work were interpreted as measures of cycling performance. This 1HTT protocol has previously been shown to be reliable in both the mean power (TEM: 7.93 W; TEM%: 4.61%) and total work (TEM: 1.492 x 104 J; TEM%: 0.01%) measures within this testing laboratory.

Physiology Measures Blood Lactate Blood lactate concentration ([BLa-]) was determined from capillary blood samples drawn from hyperaemic fingertips throughout testing. Samples were drawn into 30 ÂľL heparinised capillary tubes (Bacto Laboratories, Liverpool, NSW) and measured using an AccusportTM Lactate Analyser (Boehringer 13

Mannheim, Germany). Prior to testing, the Accusport™ analyser was calibrated using a lactate control solution (Boehringer Mannheim, Germany). Capillary blood samples were taken during the last 30 s of every second work stage during the incremental test and every 15 min across the 1HTT.

Peak [BLa-] was

analysed 3 min following the termination of the incremental test. [BLa-] measures were also taken 5 and 10 min following the completion of the incremental test in order to measure the rate of [BLa-] clearance following maximal intensity exercise.

Heart Rate Heart rate (HR) was continually recorded at 5 s intervals throughout the incremental and 1HTT tests using a Polar s610i HR monitor (Polar Electro, Oy, Kempele, Finland). HR data was downloaded to a personal computer for posttesting analysis using Polar Precision Performance Software v4.0 (Polar Electro, Oy, Kempele, Finland).

Expired Gas Analysis Expired gas measures were continuously measured throughout the incremental test and during the final 5 min of every 15 min period across the 1HTT. Breath-by-breath analysis of expired gas measures were performed using a Medgraphics CPX/D system (Medgraphics®, Parkway, USA). Expired gas was collected using a preVentTM pneumotach (Medgraphics®, Parkway, USA) and transported through sample lines, where O2 and CO2 concentrations were measured by high-response analysers (O2: Zirconia [<80 msec; ± 0.03% O2]; CO2: intra-red absorption [<130 msec; ± 0.05% CO2]). Participants wore a mouthpiece with saliva trap and nose clip during all respiratory gas testing (Medgraphics®, Parkway, USA). Prior to each test, the preVentTM pneumotach was calibrated with a 3 L syringe (Medgraphics®, Parkway, USA) and the 14

analysers calibrated with gases of known concentrations (Reference: 21 ± 0.2% O 2;

Calibration: 12.1 ± 0.2% O2, 5.05 ± 0.1% CO2) according to the

manufacturer’s instructions. Real time display of gas concentration and flow measures for each test were performed and displayed using a personal computer. . The reliability of expired gas measures at VO2max was acceptable for the current testing laboratory (TEM: 0.21 L•min-1; TEM%: 5.25%).

Near-Infrared Spectroscopy Muscle oxygenation (mOxy) of the VL muscle was monitored across both the incremental and 1HTT tests. mOxy was measured using a custom-built continuous wave near infra-red spectroscopy (NIRS) device. A probe, consisting of six light filament bulbs, two optical filters at 760 (760fs10-12.5; Andover Corporation, Salem, New Hamshsire, USA), and 850 nm (850fs10-12.5; Andover Corporation, Salem, New Hamshsire, USA) and two photodetectors (OPT301, Burr-Brown, Dallas, Texas, USA) was used to determine relative changes in oxyhemoglobin and hemoglobin concentrations during exercise testing. The distance between the diodes and photodetectors was 4 cm, and remained consistent across all tests. The probe was positioned 14 cm from the lateralsuperior border of the patella and placed over the belly of the VL. Prior to application of the probe, skinfold thickness was measured using Harpenden skinfold calipers (John Bull Instruments, UK) to the nearest 0.1 mm to ensure the signal was not distorted by excessive subcutaneous adipose tissue. All hair from the area under and immediately around the site of probe application was also shaved. A clear OpsiteTM (Smith & Nephew, London, UK) dressing was placed on the skin, underneath the photodetectors to prevent distortion caused by the accumulation of sweat. Once positioned, the probe was taped to the leg and securely bandaged to prevent movement and ensure no visible light was 15

detectable by the photodetectors. Minimal compressive forces were applied to the thigh during the application of the bandage as to not influence the observed effect of compression on the mOxy measures. All leads from the NIRS device were secured using tape to reduce any movement artifact.

The NIRS device was interfaced with a Labview NI DAQPad-6015 A/D card (National Instruments, Austin, Texas, USA), and recorded at 1 Hz. Custom written Labview software (National Instruments, Austin, Texas, USA) was written to display and record both the 760 and 850 nm signals during testing. mOxy was calculated as the difference between the 760 and 850 nm wavelengths. Calibration of the NIRS system was performed immediately prior to exercise at both the 760 and 850 nm wavelengths. Prior to each test, the mOxy signal was manually adjusted to 0 Âą 0.01 mV, in order to consider changes in mOxy relative to this point. Each wavelength had variable gain and was pre-amplified using instrumentation amplifiers. All calibration procedures were performed with the subject in the seated position on the ergometer, with their right leg at the bottom of the crank cycle. During calibration, all NIRS signals were stabilised for at least 30 s prior to testing. mOxy measures were continually recorded throughout all testing.

After the completion of each exercise test, a cuff ischemia protocol was performed on each subject to maximally deoxygenate and hyperoxygenate the VL muscle in order to quantify changes in mOxy. Cuff ischemia was undertaken after a 5 min recovery period, and involved the rapid inflation of a thigh cuff above the probe to 240 mmHg to apply suprasystolic pressure. The pressure was maintained until the mOxy signal reached a nadir, where upon the cuff was rapidly released to induce a hyperaemic response. The nadir value of the mOxy 16

signal was taken as 0% oxygenation, whereas the peak hyperaemic response was taken as 100% oxygenation. All successful mOxy values derived from . testing were normalized within this scale. The reliability of mOxy measures at V O2max was acceptable for the current testing laboratory (TEM: 3.81%; TEM%: 10.80%).

Statistical Analysis Means and standard deviations ( X Âą SD) were calculated for all descriptive, physiological and performance measures in the present study. In order to reduce the likelihood of a Type I error, a Greenhouse-Geisser adjustment was completed to ensure the sphericity of all measures. The continuous variables were examined using a Kolmogorov-Smirnov test of homogeneity to ensure that all data were normally distributed.

Firstly, traditional statistics using differences in group means were used to identify any effect of the LBCG. Paired sample t-tests were used to determine . significant conditional differences in AnT and VO2max from the incremental tests. Paired sample t-tests were also used to assess any difference in the mean physiological and performance measures from the 1HTT. A 2 (condition) x 4 (time) Repeated Measures Analysis of Variance (RMANOVA) was used to examine changes in the physiological and performance characteristics across the 1HTT. A Least Significant Differences (LSD) post-hoc comparison was used to identify any individual significant differences across the 1HTT. The magnitude of the observed differences across conditions and time was quantified using effect size statistics (Îˇ2) as described by Cohen (1992), where 0.6, 1.2 and 2.0 are representative of moderate, large and very large effects, respectively. All traditional statistical analyses were performed using Statistical Package for 17

Social Sciences software (SPSS Inc., Chicago, Illinois, USA). Statistical significance was accepted at p<0.05.

Secondly, modern statistics were used to identify practical significant differences using the spreadsheet and methods of Hopkins (2002). All modern statistical

analyses

were

performed

using

Microsoft

Excel

(Microsoft

Corporationâ&#x201E;˘, Redmond, Washington, USA). Confidence limits for the true mean values of effects were estimated with the unequal-variances statistic computed between the control and LBCG conditions. The spreadsheet provides the 95% confidence limits and calculates the likelihood that the true effects are practically beneficial, neutral or detrimental for the smallest worthwhile change. If the likelihood of benefit and detriment were both larger than 5%, the true effect was considered as unclear. If the likelihood of benefit and detriment were equal to or less than 5%, quantitative probabilities of their practical significance were assessed qualitatively as follows: < 1%, almost certainly not; 1-5%, very unlikely; 5-25%, unlikely; 25-75%, possibly; 75-95%, likely; 95-99%, very likely; and >99%, almost certainly (Spencer et al. 2006). The smallest worthwhile change for the performance variables of interest in the current study was approximately equal to the typical error of measurement of the laboratory-based 1HTT test that was utilised (Spencer et al. 2006). Such exercise performance tests, where the TEM is approximately equal to the smallest worthwhile change, have been rated as suitable (Pyne 2003). To assess the probability that the effects for the physiological variables of interest in the current study were practically significant, the smallest worthwhile changes were calculated as one-fifth of the betweensubject standard deviation for each condition (Spencer et al. 2006).

CHAPTER 3

RESULTS Incremental Tests The below results summarise the effects of wearing LBCG on endurance physiological and performance measures during repeat incremental tests. All results from the incremental tests are summarised in Table 1 below.

Table 1: The physiological and performance measures from the incremental tests in the control and LBCG conditions

Measure

Control

LBCG

RPO @ AnT (W•kg-1BM)

3.53 ± 0.78

3.68 ± 0.80*

PO @ AnT (W)

245.9 ± 55.7

259.8 ± 44.6*

HR @ AnT (b•min-1) . VO2 @ AnT (mL•kg-1•min-1)

163.5 ± 21.4

162.3 ± 20.0

40.4 ± 6.9

40.0 ± 4.7

Peak [BLa-] (mmol•L-1)

11.2 ± 1.9

11.6 ± 2.8

HRmax (b•min-1) . PO @ VO2max (W) . VO2max (mL•kg-1•min-1)

196.0 ± 11.5

195.4 ± 8.7

387.5 ± 37.7

391.7 ± 35.9

55.2 ± 6.8

53.5 ± 6.5

Peak mOxy (%)

24.2 ± 13.0

26.0 ± 18.3

* Likely to be practically significant (η2=0.6)

Power Output The results from the present study demonstrated no statistically or . practically significant improvement at the maximal power output at which VO2max . . (pVO2max) was achieved at. The average pVO2max in the control condition was . 387.5 ± 37.7 W whereas the LBCG condition demonstrated a similar pVO2max (391.7 ± 35.9 W).

Blood Lactate No statistical or practical significant effect of LBCG was observed in the [BLa-] across the repeat incremental tests as demonstrated in Figure 1 below. Predictable significant effects of time were observed in [BLa-] in both the control and LBCG conditions. 16

[BLa -] (mmol/L)

LBCG CONT 12

0 100W

200W

300W

400W

Peak

Power Output (W)

Figure 1:

Average (± SD) [BLa-] curves across the incremental tests in both the control and LBCG conditions.

Anaerobic Threshold No statistical improvement was observed in the power output at AnT with the wearing of LBCG in the present study. However, using modern statistics a practical improvement (86;12;2%: η2=0.6) was observed in the PO at AnT in the LBCG condition. Predictably, the relative power output (kg•BM-1) at AnT was also likely (78:19:3%; η2=0.6) to be greater while wearing LBCG. On average, the PO at AnT increased by ~15 W by wearing LBCG. A typical right-ward shift in the [BLa-] curve and difference in the PO at AnT between the control and LBCG conditions is shown as Figure 2. 16 LBCG

[BLa -] (m m ol/L)

CONT

~ 15 W

10 8 6

AnT

4 2 0 0

100

200

300

400

500

Power (W)

Figure 2:

Representation of a right-ward shift in the lactate curve between the control and LBCG conditions in a single subject (subject 8).

Oxygen Consumption . The present results demonstrated no difference in VO2 at AnT between the control (40.4 ± 6.9 mL•kg-1•min-1) and LBCG (40.0 ± 4.7 mL•kg-1•min-1) . incremental tests. Similarly, no significant improvement was observed in VO2max between the control (55.2 ± 6.8 mL•kg-1•min-1) or LBCG conditions (53.5 ± 6.5 . mL•kg-1•min-1). The average V O2 response across the incremental tests are shown in Figure 3. 70

VO2 (ml/kg/min)

CONT LBCG

50 40 30 20 100

150

200

250

300

350

400

450

Power Output (W)

Figure 3:

. The average (± SD) VO2 responses across the incremental tests in both the control and LBCG conditions.

Muscle Oxygenation . No significant effect of LBCG was observed in the mOxy at VO2max across the incremental tests (CNTL: 24.2 ± 13.0%; LBCG: 26.0 ± 18.3%). A representation of the changes in mOxy across the incremental tests in the two conditions is shown below as Figure 4.

Recovery

Incremental Test

Cuff Ischemia

100 CONT LBCG

mOxy (%)

80 60 40 20 0 0

Time (min)

Figure 4:

A typical representation of the mOxy responses in the control and LBCG conditions across the incremental tests (subject 8).

Blood Lactate Clearance No statistically significant effect of LBCG was demonstrated in [BLa-] clearance following the completion of the exercise test. However, a possible practical effect (73;23;5%; Îˇ2=0.6) in the absolute clearance of [BLa-] in the 10 min following termination of the incremental test. No such effect of LBCG was observed after 3 and 5 min of recovery. These results are demonstrated below in Figure 5.

8.0

[BLa -] (mmol/L)

6.0

LBCG CONT

4.0 2.0 0.0 -2.0 3

Time after Peak (min)

Figure 5:

Change in [BLa-] following the completion of the incremental test ( X ± SD) (* possible practical effect (η2=0.6))

One Hour Time-Trials The results presented below summarise the effects of wearing LBCG on endurance physiological and performance measures across a 1HTT. All results are summarised in Table 2 below.

Power Output No statistically or practically significant difference was observed in the mean power output (MPO) across the 1HTT in the control (225.8 ± 46.2 W) and LBCG (226.2 ± 50.0 W) conditions. The relative mean power output (rMPO) was also similar between the two conditions (CNTRL: 3.18 ± 0.77 W•kg-1; LBCG: 3.18 ± 0.74 W•kg-1). The peak power output (PPO) was also similar between the two conditions (CNTL: 301.8 ± 56.2 W; LBCG: 298.8 ± 51.4 W). Similarly, no significant effect of time was observed in MPO, rMPO or PPO in either the control 24

or LBCG conditions. The average power output profile from the two conditions is shown below as Figure 6.

300 LBCG CONT Power (W)

250

200

150 0

Time (min)

Figure 6:

The average power output across the 1HTT in both the control and LBCG conditions.

Work No difference was reported in the total work between the control (8252.7 ± 1690.0 kJ) and LBCG (8264.2 ± 1829.6 kJ) in the current study. Similarly, no difference was observed in relative total work between the two conditions (CNTL: 11.64 ± 2.82 kJ•kg-1; LBCG: 11.61 ± 2.70 kJ•kg-1). No significant effect of time was observed in either condition for absolute or relative work completed during 15 min intervals across the 1HTT.

Table 2: Physiological and performance measures across the 1HTT in the control and LBCG conditions (n=10)

Control

LBCG

0 - 15 min

15 - 30 min

30 - 45 min

45 – 60 min

Overall

0 - 15 min

15 - 30 min

30 - 45 min

45 – 60 min

Overall

3.6 ± 1.0

4.3 ± 2.5

4.2 ± 2.9

7.8 ± 3.7

5.0 ± 2.6

4.7 ± 1.8

4.0 ± 1.4

4.5 ± 1.4

7.0 ± 2.8

5.0 ± 1.9

163.2 ± 20.9

171.8 ± 19.7

165.5 ± 21.3

171.8 ± 19.7

165.3 ± 7.5

161.6 ± 21.2

166.1 ± 20.7

167.0 ± 19.8

171.9 ± 19.4

166.6 ± 7.2

VO2 (mL•kg-1•min-1)

39.3 ± 8.1

37.8 ± 6.9

37.9 ± 6.6

39.6 ± 7.9

38.0 ± 3.9

39.8 ± 6.5

38.6 ± 6.3

37.2 ± 4.8

40.7 ± 5.5

39.3 ± 3.7

mOxy (%)

42.3 ± 7.9

63.3 ± 19.9

55.0 ± 16.1

48.3 ± 18.6

52.2 ± 12.2

48.4 ± 5.9

58.7 ± 9.5

61.8 ± 12.2

49.0 ± 2.7

57.3 ± 8.2*

MPO (W)

216.5 ± 42.7

220.7 ± 45.7

218.0 ± 46.9

231.7 ± 49.1

225.8 ± 46.2

223.9 ± 47.6

226.5 ± 51.5

222.0 ± 50.3

232.4 ± 53.4

226.2 ± 50.0

PPO (W)

264.7 ± 54.7

233.9 ± 48.1

246.9 ± 60.1

279.3 ± 67.3

301.8 ± 56.2

276.2 ± 42.7

252.1 ± 65.1

241.7 ± 66.0

277.8 ± 70.8

298.8 ± 51.4

Total WO (kJ)

208.1 ± 40.6

202.7 ± 41.2

200.3 ± 42.5

214.1 ± 47.0

825.3 ± 169.0

211.1 ± 45.0

203.5 ± 46.4

200.1 ± 45.4

211.7 ± 4.9

826.4 ± 182.9

[BLa-] (mmol•L-1) HR (bpm)

* possibly practically significant (η2=0.6)

Blood Lactate No difference was observed in mean [BLa-] in either the control (5.0 ± 2.6 mmol•L-1) or LBCG (5.0 ± 1.9 mmol•L-1) across the 1HTT in the present study. No significant effect of time was observed in [BLa-] in either experimental condition across the 1HTT. Figure 7 shows the average [BLa-] across the 1HTT in both conditions.

8 6

[BLa ] (mmol/L)

LBCG CONT

4 2 0 15

Time (min) Figure 7:

[BLa-] values across the 1HTT in the control and LBCG conditions ( X ± SD)

Oxygen Consumption . No significant effect of LBCG was observed in mean VO2 across the 1HTT (CNTL: 38.0 ± 3.9 mL•kg-1•min-1; LBCG: 39.3 ± 3.7 mL•kg-1•min-1). No significant . effect of time was reported in VO2 across the 1HTT in either condition.

Muscle Oxygenation No statistically significant effect of LBCG was observed in mOxy across the 1HTT. However, wearing LBCG (57.3 ± 8.2 %) appeared to facilitate a possible (62:28:10%; η2=0.6) improvement in mean mOxy compared to the control (52.2 ± 12.2%) across the 1HTT. Given the similar power output and higher mOxy levels during the 1HTT, this result may be suggestive that wearing LBCG facilitates greater muscular efficiency. No significant effect of time was observed in mOxy across the 1HTT in either condition. A typical representation of the mOxy trends in both the control and LBCG conditions across the 1HTT is shown below.

Cuff Ischemia 1HTT

100

LBCG CONT

80 mOxy (%)

Recovery

60 40 20 0 0

Time (min) Figure 8:

A typical representation of the mOxy responses in the control and LBCG conditions across the 1HTT (subject 8).

CHAPTER 4

DISCUSSION The purpose of the current investigation was to examine the effects of LBCG on endurance physiological and performance measures in high-performance cyclists. To date, no research had examined the effects of wearing LBCG on endurance cycling performance, and limited data having reported their effects on any such athletic performance (Ali et al. 2006; Chatard, 1998). The results of the present study demonstrated no statistically significant effect of wearing LBCG in any physiological or performance measures across the incremental or 1HTT tests. However, modern statistics suggested practically significant physiological benefits in both power output at AnT and average mOxy reported across the incremental and 1HTT tests, respectively in the LBCG condition. However, neither likely effect corresponded to any significant improvement in endurance cycling performance.

Effects of LBCG during the incremental test No statistically significant effect of wearing LBCG was observed in any physiological measure across the repeat incremental tests. However, wearing LBCG produced likely practical significant improvements in both the relative (W kg BM-1) and absolute (W) PO at AnT. These observed increases in the PO at AnT may be due to the proposed improvements in circulatory associated with wearing LBCG. The observed increase in AnT may reflect greater diffusion and oxidisation of La- outside the working muscle as a result of improved circulation to the working muscle.

Previous research has suggested that LBCG significantly increases venous circulation by improving the linear velocity of venous flow, reducing venous wall distension and improving venous valve function (Agu et al. 2006; Saltin et al. 1998). These benefits may subsequently enhance clearance of deoxygenated blood and waste products towards central portions of the body (Moffat, 2002). Such improved circulation and removal of waste products may help to reduce the accumulation of anaerobic by-products within the working muscle which are often related to metabolic fatigue (Myers and Ashley, 1997). The accumulation of hydrogen ions (H+), from lactic acid dissociation, has been reported to impair muscle contraction and influence high-intensity exercise performance (Myers and Ashley, 1997). Therefore, the circulatory benefits associated with LBCG may help to facilitate greater removal of BLa- and H+ from the working muscle to nonactive central and peripheral tissues for removal. The improved transportation of these waste products to non-active tissue and organs may allow an improved rate of oxidation during and following high-intensity exercise (Myers and Ashley, 1997).

Alternatively, the improvements in the PO at AnT in the LBCG condition may have resulted from the application of compressive forces which may have restricted the transport of blood and metabolites from within the muscle during exercise. If excessive compression is applied, arterial circulation may be reduced which may slow the removal of waste products from the working muscle (Moffat, 2002). This compression effect may have demonstrated a lowered [BLa-] and slower diffusion of BLa- out of the muscle at identical power output between the two tests and as such, biased the AnT power output calculations. This proposed effect is novel, but appears worthy of further research. Given that the power output at AnT has previously been suggested to be a valid predictor of 30

endurance cycling performance (Amann et al. 2004; Berran et al. 2006), the observed increases in the present study are of great interest to both athletes and coaches.

The current study contrasts previous investigations that have reported significant improvements in aerobic capacity while wearing CG (Lambert, 2005). Previously, Lambert (2005) reported that wearing full body compression . garments produced a significant 40% increase in VO2 at AnT and a 10% increase . in VO2max across an incremental test in recreational athletes. The investigator . hypothesised that these increases in VO2max were the result of an increased utilisation of O2 within the working muscle, which was facilitated by the circulatory benefits. The results of the present study demonstrated no significant increase in . . V O2 at AnT or V O2max in the LBCG condition. Further, the hypothesis of . Lambert (2005) put forward to explain their observed increase in VO2max with WBCG was contradicted changes in mOxy being similar across the repeat incremental tests in the current study.

The present results support the recent observations of Bernhardt and Anderson (2005) who reported no effect of LBCG (49.88 ± 8.34 mL•kg-1•min-1) on . VO2max compared to loose shorts (49.64 ± 8.34 mL•kg-1•min-1) during a multistage fitness test. These researchers suggested that the LBCG in their study exerted inadequate pressure to facilitate substantial changes in blood flow that . has been suggested to be required to increase VO2max. Previously, it has been suggested that 18 mmHg and 8 mmHg of compression are required at the ankle and mid-thigh, respectively in order to elicit an increase in venous return and associated hemodynamic responses (Lawrence and Kakkar 1980). The LBCG used in the present study exerted greater compression (~19 and ~17 mmHg at 31

the ankle and mid-thigh, respectively) than this suggested threshold, but still . failed to elicit any benefits in V O2 or mOxy. Nevertheless, it has also been suggested and demonstrated that increases in O2 to the working muscle does . not necessarily correspond to increases in VO2 and mOxy (Grassi, 2005). Rather, these researchers have suggested that the capacity to extract and utilise O2 within the working muscle during exercise is the limiting factor for these measures. Therefore, while wearing LBCG may increase venous return and cardiac output, it is likely that this will not translate into increases in . VO2max or changes in mOxy within the working muscle. However, other factors . have also been suggested to influence changes in V O2 during submaximal exercise, including blood redistribution and thermoregulatory processes, which may also be influenced by wearing LBCG (Bhambhani et al. 1999; Kawagucki et al. 2006).

The current results demonstrated faster [BLa-] clearance following the completion of the incremental tests in the LBCG condition. The results showed that [BLa-] had decreased by around ~5 mmolâ&#x20AC;˘L-1 in the LBCG compared to 4 mmolâ&#x20AC;˘L-1 in the control condition. Previous, wearing LBCG has been reported to speed [BLa-] clearance following high-intensity exercise in a number of investigations (Berry & McMurray, 1987; Chatard et al. 2004; Lambert & Chow, 2004). These researchers have suggested that the improved venous return from the working muscle associated with wearing LBCG is responsible for the improved [BLa-] clearance. As discussed above, the increased circulation (both arterial and venous) through the working muscle may help to facilitate greater Ladiffusion out of the muscle and transport it to peripheral muscles and organs for oxidation or gluconeogenesis (Chatard et al. 2004). While the positive effect of

wearing LBCG on [BLa-] clearance has been reported previously, the current study supports these previous findings.

In summary, the present data does not support the previous findings of a . significant improvement in V O2max through wearing CG (Lambert, 2005), but does suggest that the power output at AnT is improved by wearing LBCG. However, while this result has the potential to suggest a likely improvement in endurance cycling performance, no such corresponding benefit was observed across the 1HTT. Further, wearing LBCG also demonstrated a likely benefit in [BLa-] clearance following maximal intensity exercise in the present study, most likely due to their hemodynamic benefits. However, while these findings are important for athletes and coaches, as to whether they correspond to performance enhancements is of greater value.

Effects of LBCG on 1HTT performance The present data demonstrated no statistically significant improvements in any physiological or performance measures in the LBCG condition during the 1HTT. Using modern statistics, possible practical significant higher mOxy was observed across the 1HTT which may reflect an improvement in efficiency, but this did not correspond to any 1HTT performance benefits.

The possible practical significant higher mOxy observed with the wearing of LBCG across the 1HTT contrasts previous research hypotheses (Lambert, 2005). The current results demonstrated that wearing LBCG produced a greater average tissue O2 saturation across the 1HTT, which may suggest either an increase in muscular efficiency across the 1HTT or less O2 utilisation within the working muscle. Given that the PO across the 1HTT was similar between 33

conditions, it can be suggested that the LBCG facilitated greater muscular efficiency (as defined by W per unit (%) of mOxy). Previously, it has been hypothesised that wearing CG enhances O2 delivery and utilisation to and within working muscles, which would have appeared as lower mOxy values (Lambert, 2005). The difference in mOxy observed in the current study suggests that wearing LBCG enhanced muscular efficiency rather than O2 utilisation within the active tissue. Similar responses with wearing CG have been observed in endurance running performance (Bringard et al. 2006). Bringard and colleagues (2006) observed an increased metabolic efficiency at a given submaximal workload in six trained runners through wearing LBCG. The researchers proposed that reductions in muscle oscillation and circulatory benefits were responsible for the observed improvements in efficiency. However, while these measures were not measured in the current study, and given the biomechanical differences between running and cycling it may be possible that wearing LBCG facilitates a physiological mechanism to enhance metabolic efficiency. Despite not being related to improvements in cycling performance, these results are promising, and suggest further research is required to identify any such ergogenic mechanisms.

To date, no research had investigated the effects of wearing LBCG on endurance cycling performance, and the present study observed no significant benefits in 1HTT performance. Previously, investigations have reported on the effect of LBCG on endurance running performance, and produced equivocal results (Ali et al. 2006; Chatart, 1998). Ali and colleagues (2006) reported no significant effects of LBCG on 10 km running time in 14 young running-based male athletes. In contrast, Chatard (1998) reported a significant 31 s decrease in 5 km running time in ten competitive runners by wearing LBCG. The investigators 34

suggested that the improved performance benefit was a result of decreased stride length, resulting from the elastic nature of the garment. This may have limited excessive knee extension during the swing phase of the running cycle and consequently improving running efficiency. Therefore, the difference in the performance results between the current study and that of Chatard (1998) may reflect the biomechanical differences between cycling and running modalities. Given the absence of a stretch-shortening cycling during the cycle stroke, the elastic potential of the LBCG may not have had an effect during the cycle stroke.

No difference was observed in any physiological measure across the 1HTT between the control and LBCG conditions. The similar physiological intensities observed across the 1HTT support the near identical power and work outputs across the two conditions. However, the physiological measures are not suggestive of any reason that may have lead to an increase in muscular efficiency across the 1HTT, as a similar benefit in efficiency was not observed in any other physiological measures. These parameters were taken as measures of endurance cycling performance, and as such, no significant improvement as observed in performance facilitated by wearing LBCG in the present study.

Limitations The

absence

any

significant

physiological

performance

improvements in the LBCG condition may also have resulted from a number of methodological limitations. Firstly, the pressure of the LBCG used in the present study may have been inadequate to facilitate the proposed physiological changes related to hypothesised performance benefits. The LBCG in the current study were fitted according to stature and body mass rather than individual body segment dimensions, and consequently the exerted compression varied across 35

subjects. Previous data has suggested that significant improvements in mOxy are only observed in LBCG that exert between 25-35 mmHg of compression at the ankle (Agu et al. 2004), whereas the LBCG used in the present study only exerted 19 mmHg at the ankle. However, LBCG that exert 19 mmHg and 17 mmHg at the ankle and mid-thigh, respectively have been shown to increase venous return (Lawrence and Kakkar 1980). Importantly, no research has investigated as to the critical level of compression that is required to facilitate any proposed physiological and performance benefits in endurance exercise. Future research should aim to investigate as to whether a critical compression threshold of LBCG is exists to facilitate significant performance or efficiency benefits.

A second limitation of the present study was the use of LBCG, rather than whole body compression that previous investigations have employed to show endurance benefits (Lambert, 2005). During cycling at intensities above 60% . , whereas the upper body (trunk VO2max, the lower-body receives 70% of total Q and arms) receives up to 30% (Calbet et al. 2006). Therefore, the use of whole body compression may have facilitated greater circulatory improvements and to the working muscles, which in turn may have elicited greater increases in Q

improvements in endurance performance. To date, no data has compared the differences in endurance physiological and performance responses between whole-body and lower-body compression, and future research should address this problem.

Summary In summary, the present study observed no significant improvements in any endurance physiological or performance measure in high-performance cyclists. The current data demonstrated that wearing LBCG appeared likely to 36

improve both AnT across the incremental test, and muscular efficiency across a 1HTT. The most plausible mechanism behind these practical benefits is improved circulation within the working muscles, but future research is required to investigate this hypothesis. This is the first study to specifically examine the effects of LBCG on endurance cycling performance, and no significant improvements in any physiological or performance measures were observed.

CHAPTER 5

SUMMARY The primary purpose of the present investigation was to examine the effects of LBCG on physiological and endurance performance measures in highperformance cyclists. A secondary purpose was to identify any physiological mechanisms related to observed improvements in performance with the wearing of LBCG across a 1HTT.

Twelve young male competitive cyclists (( X ± SD) age: 20.5 ± 3.6 yr; . height: 177.5 ± 4.9 cm; body mass: 70.5 ± 7.5 kg; V O2max: 55.2 ± 6.8 mL•kg-1•min-1) volunteered to participate in the current study. Subjects underwent a familiarization session prior to testing. Subjects then performed repeat incremental tests and 1HTT in a randomized order under control (underwear) and LBCG (Sport Skins Classic, SkinsTM, Campbelltown, NSW) conditions. . During all exercise testing, [BLa-], HR, V O2 and mOxy were measured for . analysis. AnT and VO2max were taken as important physiological performance measures from the incremental tests. Absolute and relative PO and total work were taken as measures of endurance cycling performance from across the 1HTT. Significant condition effects between the control and LBCG conditions were analysed using traditional (p<0.05) and modern (% of positive: neutral: negative effect) statistics.

The results of the present investigation suggest that the LBCG condition did not significantly improve the majority of the physiological or performance measures of endurance cycling performance examined. However, likely practical 38

significant (86:12:2%; η2= 0.6) improvements were observed in the PO at AnT in the LBCG condition (259.8 ± 44.6 W) compared to the control (245.9 ± 55.7 W) condition. Similarly, wearing LBCG produced a likely practical improvement (73;23;5%; η2=0.6) in [BLa-] clearance following the completion of the incremental test. Possible practical significant (62:28:10%; η2=0.6) improvements were also observed in muscular efficiency in the LBCG condition across the 1HTT. This improvement in efficiency was represented through higher average mOxy in the LBCG condition (57.3 ± 8.2%) compared to the control condition (52.2 ± 12.2%) despite similar 1HTT PO and total work measures. The most likely explanation for the observed practical effects of LBCG in the current study and waste product is the proposed improvements in venous circulation, Q removal, previously reported to result from wearing CG. Regardless, the reported physiological benefits associated with the wearing of LBCG do not correspond to significant improvements in endurance cycling performance across a 1HTT. The current study is the first study to examine the effects of wearing LBCG on physiological and performance measures in endurance cyclists. The results from the current study suggest that wearing LBCG do not significantly improve endurance cycling performance, but may facilitate some possibly or likely physiological benefits.

CHAPTER 5

FUTURE RECOMMENDATIONS The results from the current study concerning the physiological and performance effects of LBCG in high-performance cyclists has lead to several suggestions for future research in order to further examine their effects. These questions largely relate to critical compression levels, garment types and regional blood flow measurement.

Critical Levels of Compression To date, no research has investigated the critical level of compression that is required to facilitate the proposed benefits in the physiological and/or performance responses reported. Future research investigating the effects of wearing CG needs to incorporate the assessment of a range of pressures exerted by CG, so that it may be determined as to whether a compression threshold is required to facilitate specific physiological and performance responses.

Types of Compression Garments The current investigation examined the effects of only LBCG on endurance cycling performance, and did not aim to report upon the effects of whole-body compression. Future research is warranted to examine the physiological and performance effects of different compression coverage given that the upper portion of the body receives considerable blood flow during high-intensity cycling (Calbet et al. 2006).

Regional Blood Flow Measurements Existing literature researching CG suggests that improvements in circulation and blood redistribution are major physiological mechanisms underpinning their benefits in endurance activities (Berry & McMurray, 1987; Kraemer et al. 2001; Shim et al. 2001; Chatard et al. 2004; Lambert, 2005; Bringard et al. 2006). To date, no research has examined the effects of CG on regional blood flow changes within working muscles during high-intensity exercise. Further research should examine the effects of CG on changes in regional blood flow and circulation within their methodological procedures to investigate this as a mechanism behind improved performance.

CHAPTER 6

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