A Literature Review done for my Masters in Sports Medicine (MsSpMed), University of Queensland, Australia 2017

• Introduction
• Results
• Discussion
• Effects of CG on Markers of Running Performance
• Heart Rate
• Rating of Perceived Exertion (RPE)
• Oxygen Uptake (VO2), Maximum Oxygen Uptake (VO2max) and Running Economy
• Lactate Threshold (LT)
• Time to Exhaustion (TTE)
• Limitations
• Recommendations
• Future Studies
• Impact on Current Practice
• Conclusion
• References

Introduction

The first men’s marathon world marathon record  was 3hours and 18minutes, set by Greek runner Kharilaos Vasilakos in 1986. A mere 3 decades later, the record has been brought down to 2hours, 2 minutes and  57seconds, set in 2014 by Kenyan Dennis Kimetto19. As running performances approach the limits of the human body, records are being broken with the smallest of margins, leading to research being done on methods to enhance human performance.

Compression stockings have been used for many years in the prophylaxis of deep vein thrombosis in the medical field. In high performance sports such as distance running, metabolites such as acidic hydrogen ions are produced during races and these are thought to decrease running performance when allowed to accumulate18. Mechanical pressure resulting from the application of external compression on the muscles increases the linear velocity of blood flow in the venous system17. It is hypothesized that this increased blood flow can improve the clearance of by-products and thus improve performance. Paula Radcliffe first popularised the use of compression stockings in running  when she broke the women’s marathon world  record with a time of 2 hours, 15 minutes and 25 seconds in the 2003 London Marathon20 while using them during the race.

This literature review aims to identify the effects of CG on running performance.

Results

A literature search was done on Pub Med to elicit recent studies on the effects of CG on performance enhancement. 13 randomised cross-over studies which compared running performance between experimental and control groups were found. The results are summarised in table 1.

Table 1. Studies investigating the effects of compression clothing (CG) on Performance Enhancement

Discussion

There is no convincing evidence that the use of CG improves running performance. This review will discuss the various markers which are frequently used to judge running performance and how use of CG may affect them.

Effects of CG on Markers of Running Performance

Heart Rate

Heart rate gives a good gauge on how hard the athlete is running. With all things equal, the lower the physical exertion, the lower the heart rate of the subject. The use of CG has been postulated to assist the skeletal muscle pump which in turn increases venous return14. With an increased venous return, based on the Starling’s law, the runner will experience a reduction in heart rate when running at the same speed. In this literature review, most studies did not find a significant impact on heart rate except for Dascombe et al.1 and Varela-Sans et al. 11 which found a significant lowering of heart rate at moderate and high intensity running respectively, however this was not correlated with any improvements in running performance itself.

As such, more studies need to be done to ascertain if heart rate when running at a certain speed is an accurate predictor of running performance.

Rating of Perceived Exertion (RPE)

Rating of perceived exertion is a subjective measurement of effort determined by the athlete. It can be highly dependant on the athletes’ knowledge of the presumed benefits of CG, and possibly resulting in the placebo effect. A previous study2 found that 93% of subjects felt that compression garments were “supportive” despite no improvement in performance markers. Even though one4 out of the five studies looking at the effects of CG on RPE found an improvement in RPE when using CG in a warm environment (32ºC), there is an element of possible bias present.

Due to its subjective nature, RPE may not be an ideal measurement for running performance. Further discussion on the use of a subjective marker and the possibility of a placebo effect will be done later.

Oxygen Uptake (VO2), Maximum Oxygen Uptake (VO2max) and Running Economy

Oxygen uptake by the body increases as running intensity increases because more oxygen is required for glucose metabolisation to produce energy. By measuring VO2, one can calculate running economy21. Conventionally, running economy is calculated by measuring steady state VO2 while running at a fixed speed (most commonly at 16km/h) and expressing it relative to body mass per minute (ml.kg-1min-1). Therefore, if the use of CG improves running performance, we will see a decrease in VO2 (or an increase in running economy)  when athletes are running at the same speed. This effect is postulated to be due to a  decrease in muscle oscillations to promote a lower energy expenditure (i.e. lessening muscle fatigue). Only one study7 found a reduction in VO2 when full lower limb CG was used. However, this effect was only seen when running at 12km/h but not at 10, 14 or 16km/h.

VO2max refers to the maximum amount of oxygen the body is capable of utilizing in 1 minute. This is usually measured by doing an incremental ramp test on the treadmill while measuring VO2 throughout the test. The runner is made to run increasingly faster or harder until the VO2 plateaus at the VO2max or until exhaustion. Varela-sanz et al.11 found a negative impact of CG on VO2max (~53 vs 62ml.kg-1min-1, p=0.09) while other studies did not find any significant differences among different conditions.

Oxygen Uptake (VO2), Maximum Oxygen Uptake (VO2max) and Running Economy are good objective markers of running performance and should be used in future studies.

Lactate Threshold (LT)

Lactate is produced as a by product in anaerobic cellular respiration where glucose is directly broken down in the absence of oxygen to give energy and lactate. Lactate threshold (LT) is the pace at which the runner’s blood concentration of lactate begins to exponentially rise. In endurance running, the higher the pace that the LT is at, the faster the athlete can race at without utilising anaerobic respiration which is a less efficient pathway of energy production. The one study which studied the effects of CG on LT found that the LT of runners improved by between 2.1% to 6.2% with the use of below knee compression socks9.

Future studies should utilise lactate threshold as a performance marker to provide more data for comparison.

Time to Exhaustion (TTE)

Time to exhaustion is typically recorded from the start of the run at submaximal velocity (which can be either velocity at VO2max or a predetermined velocity) until volitional exhaustion. One limitation of using TTE as a measurement of performance improvement is that it does not allow for pacing which is a key component of running performance. In a race where an athlete attempts to run a fixed distance in a time as short as possible, he may be able to draw strength knowing that there is an end point in sight. However, in the TTE test, the end point is variable, taking this mental aspect of running performance out of the equation. This can affect the applicability of these results to real-life racing.

In this literature review, studies have found conflicting effects of the use of CG on TTE. Future studies can consider using other objective performance markers that will provide better real-life applicability.

Limitations

There are several limitations in the study designs that should be highlighted and addressed in future studies.

Placebo Effect

It is pertinent to note that it is difficult to create a placebo for compression clothing because participants are bound to feel the lack of compression of the garments provided to them in the control setting. Thus, one may query whether the few positive findings on running  performance obtained in these studies might at least partially be dependant on the increased motivation of the participants who have a preconceived idea that compression will help them in their performance. As Kemmler et al.9 pointed out, this would be difficult to determine although physiological parameters that suggest voluntary increased exertion such as a higher maximum heart rate would concurrently be present in these studies that showed positive results. This was not fully discussed in the studies but will greatly impact the way results are interpreted.

Hill et al.25 who studied on the effects of CG on athletic recovery attempted to get around this psychological mindset by introducing a sham ultrasound treatment for the control group. This could be a possible way to let participants think that they are provided with an alternative form of performance enhancement.

Future studies should investigate physiological parameters to determine the presence of the placebo effect as well as to blind participants using novel techniques.

Ecological Validity

Most of the studies employed the use of a treadmill to make runners run at a certain speed and attempt to measure performance via different modalities. This provides a much controlled setting in which tests can be carried out in which can be easily replicated for all participants. However, it is also well established that running on a treadmill changes running kinematics such as the reduction of peak impact force compared to overground running on stiff surfaces. Thus, these results may not be fully applicable to runners who train and race on the roads. Ali et al.6,8 attempted to get around this by doing a field-based 10km road time trial for its participants. Pace was maintained for the participants by having investigators ride beside them on bicycles throughout the trial. Vecruyssen et al.12 also designed a 15.6km cross country course to carry out the tests.

However, it is understandable that objective measurements such as VO2 requires sophisticated equipment that can only be used while the runner is on the treadmill. Nevertheless, this limitation should thus be kept in mind when applying research results to elite runners training for road and track races.

Recommendations

Future Studies

Higher quality studies should be carried out to determine the relationship between the use of CG and running performance. Attempts should be made to overcome the placebo effect as well as to design a study that has a high ecological validity. With regards to performance indicators, more focus can be placed on objective markers such as lactate threshold and oxygen uptake instead of subjective markers such as Ratings of Perceived Exertion.

Impact on Current Practice

There is currently limited evidence that the use of compression garments while running can improve performance. In my practice, I will not specifically advocate the use of compression garments in athletes. However, should they feel comfortable when wearing them, I will not discourage them as there is a role of the placebo effect which can increase their motivation to do well.

Another common question by runners is which type of compression garments should they wear – high knee compression socks, quadriceps only compression or full length tights? Only one study5 compared the differences in performance when using different forms of compression and found no performance benefits in using either of them. Thus, this would again depend highly on the subject’s own comfort.

As I practice in a tropical climate, I am also concerned about compression garments, which inadvertently reduces exposed skin area for cooling, as a risk factor for heat injuries. It is widely accepted that excessive clothing wear can result in thermal insulation and subsequent detriment exercise performance and increase the risk of heat injuries15, 16. Only one study4 investigated the effects of CG on running performance in heat, finding no difference in skin or rectal temperature observed at 32ºC. However, it is important to note that while participants in the study only exercised for 30minutes , runners may take more than 2 hours to complete a marathon.  There is still thus a possible risk of heat exhaustion when the duration of exercise increases. Therefore, I would discourage runners from using compression garments in a tropical climate, especially those that cover a large skin area. However, should a runner still chooses to wear CG on race day, I would recommend that he or she go through period of acclimatisation by wearing them on their training runs.

Conclusion

Till date, studies have not been entirely convincing in their results to suggest a positive impact on running performance by the use of CG. However, several weaknesses limit the interpretation of the results and more high quality studies should be done in this field.

References

1. Dascombe BJ, Hoare TK, Sear JA, Reaburn PR, Scanlan AT. The effects of wearing undersized lower-body compression garments on endurance running performance. Int J Sports Physiol Perform. 2011 Jun;6(2):160-73.
2. Sperlich B, Haegele M, Kruger M, Schiffer T, Holmberg H-C, Mester J. Cardio-respiratory and metabolic responses to different levels of compression during submaximal exercise. Phlebology. 2011;26(3):102–106.
3. Ali A, Creasy RH, Edge JA. Physiological effects of wearing graduated compression stockings during running. European Journal of Applied Physiology. 2010;109(6):1017–1025.
4. Goh SS, Laursen PB, Dascombe B, Nosaka K. Effect of lower body compression garments on submaximal and maximal running performance in cold (10°C) and hot (32°C) environments. European Journal of Applied Physiology. 2010;111(5):819–826.
5. Sperlich B, Haegele M, Achtzehn S, Linville J, Holmberg H-C, Mester J. Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes. Journal of Sports Sciences. 2010;28(6):609–614.
6. Ali A, Caine MP, Snow BG. Graduated compression stockings: Physiological and perceptual responses during and after exercise. Journal of Sports Sciences. 2007;25(4):413–419.
7. Bringard A, Perrey S, Belluye N. Aerobic energy cost and sensation responses during Submaximal running exercise - positive effects of wearing compression Tights. International Journal of Sports Medicine. 2006;27(5):373–378.
8. Ali A, Creasy RH, Edge JA. The effect of graduated compression stockings on running performance. Journal of Strength and Conditioning Research. 2011;25(5):1385–1392.
9. Kemmler W, Stengel S von, Köckritz C, Mayhew J, Wassermann A, Zapf J. Effect of compression stockings on running performance in men runners. Journal of Strength and Conditioning Research. 2009;23(1):101–105.
10. Rider BC, Coughlin AM, Hew-Butler TD, Goslin BR. Effect of compression stockings on physiological responses and running performance in division III collegiate cross-country runners during a maximal treadmill test. Journal of Strength and Conditioning Research. 2014;28(6):1732–1738.
11. Varela-Sanz A, España J, Carr N, Boullosa DA, Esteve-Lanao J. Effects of gradual-elastic compression stockings on running economy, Kinematics, and performance in runners. Journal of Strength and Conditioning Research. 2011;25(10):2902–2910.
12. Vercruyssen F, Easthope C, Bernard T, et al. The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise. European Journal of Sport Science. 2012;14(2):144–150.
13. Stickford AS, Chapman RF, Johnston JD, Stager JM. Lower-leg compression, running mechanics, and economy in trained distance runners. International Journal of Sports Physiology and Performance. 2015;10(1):76–83.
14. Mayberry JC, Moneta GL, De Frang RD, Porter JM. The influence of elastic compression stockings on deep venous hemodynamics. Journal of Vascular Surgery. 1991;13(1):91–100.
15. BROWNLIE L, MEKJAVC I, BANISTER E. Thermoregulation in athletic racing apparel. The Annals of physiological anthropology. 1987;6(3):145–155. doi:10.2114/ahs1983.6.145.
16. Gavin TP. Clothing and Thermoregulation during exercise. Sports Medicine. 2003;33(13):941–947. doi:10.2165/00007256-200333130-00001.
17. Ido K, Suzuki T, Taniguchi Y, et al. Femoral vein stasis during laparoscopic cholecystectomy: Effects of graded elastic compression leg bandages in preventing thrombus formation. Gastrointestinal Endoscopy. 1995;42(2):151–155. doi:10.1016/s0016-5107(95)70072-2.
18. Chatard J-C, Atlaoui D, Farjanel J, Louisy F, Rastel D, Gu�zennec C-Y. Elastic stockings, performance and leg pain recovery in 63-year-old sportsmen. European Journal of Applied Physiology. 2004;93(3):347–352. doi:10.1007/s00421-004-1163-9.
19. Marathon world record progression. Wikimedia Foundation; December 15, 2015. https://en.m.wikipedia.org/wiki/Marathon_world_record_progression. Accessed January 10, 2016.
20. Caesar E. What was the secret of Paula Radcliffe’s exceptional London marathon? The Guardian. June 30, 2015. http://www.theguardian.com/lifeandstyle/the-running-blog/2015/jun/30/secret-paula-radcliffe-2003-london-marathon. Accessed January 10, 2016.
21. Barnes KR, Kilding AE. Running economy: Measurement, norms, and determining factors. Sports Medicine - Open. 2015;1(1).
22. Bernhardt T, Anderson GS. Influence of moderate Prophylactic compression on sport performance. The Journal of Strength and Conditioning Research. 2005;19(2):292.
23. Lawrence D, Kakkar VV. Graduated, static, external compression of the lower limb: A physiological assessment. British Journal of Surgery. 1980;67(2):119–121.
24. Davies V, Thompson KG, Cooper S-M. The effects of compression garments on recovery. Journal of Strength and Conditioning Research. 2009;23(6):1786–1794.
25. Hill JA, Howatson G, van Someren KA, Walshe I, Pedlar CR. Influence of compression garments on recovery after marathon running. Journal of Strength and Conditioning Research. 2014;28(8):2228–2235.