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Sports clothing: how lycra affects performance
The lure of enhanced performance and recovery means that compression clothing is becoming increasingly popular among sportsmen and women. But does this type of clothing really deliver the goods? Andy Harrison and Kevin Thompson look at the evidence
There’s no strict definition of what precisely what constitutes compression clothing, but common to all these garments is a very elastic quality, courtesy of the high Lycra content. When wearing compression clothing, the material clings tightly to the skin, quite literally squeezing the muscles below but without discomfort. The higher the Lycra content, the stronger this compression effect is, with anecdotal reports suggesting that around 70% Lycra content producing an optimum effect.
The early studies on compression clothing mainly looked the reduction of thrombosis in hospitalised patients, but when it was found that these garments increased venous blood flow to the extremities of the body, sports scientists began to investigate the effect of compression clothing on athletic performance. For example, one study showed that volleyball players wearing compression clothing were able to maintain maximal jumping power for longer than without1. Then in 2003, another study demonstrated that explosive/sprint athletes wearing compression shorts suffered less muscle oscillation during the landing phase and were able to increase their countermovement jump heights compared with ordinary shorts2. There’s evidence that these benefits occurred as a result of enhanced perception of joint movement and spatial location, via neural feedback (known as proprioception).
Compression clothing and aerobic activities
Recent research also indicates that compression clothing may confer a physiological advantage during sub-maximal exercise. In a study on six endurance-trained runners, scientists looked at the effects of compression tights (compared to non-compressive elastic tights and ordinary shorts) on the oxygen cost while running at speeds from 10-16kmh, followed by a 15-minute run at 80% of VO2max3. The findings were as follows:
• At 12kmh, the oxygen cost of running in compression tights was less than in shorts, with similar, but non-significant trends noted at other speeds;
• At 80% of VO2max, the rise in oxygen consumption from the 2nd minute to the end of the run while wearing the compression tights was less than both that of elastic tights and shorts.
Scientists have speculated that the benefits of compression clothing on aerobic performance may be due to reduced muscle oscillation (from running impact) and increased support of the active muscles, with the applied pressure acting to support the fibres of the muscle in the direction of their contraction.
Can compression clothing enhance recovery?
Because compression clothing is known to enhance venous return via an improved ‘muscle pumping’ action, scientists have investigated whether this could also lead to enhanced lactate removal and faster recovery. In one study, six subjects ran on a treadmill and cycled on a stationary bike at 110% of VO2max (ie producing large amounts of lactate) with and without compression stockings4. After both running and cycling, post-exercise blood lactate was significantly lower when wearing compression stockings. However, the researchers speculated that this was because the stockings caused retention of lactate in the muscles, rather than enhanced lactate removal.
Meanwhile a New Zealand study looked at the effects of compression clothing on immediate, 36 and 84-hour recovery in elite rugby players by measuring a marker of muscle damage called creatine kinase5. Compared to contrast water therapy, and low-intensity active cool-down, compression clothing was equally effective in lowering blood creatine kinase levels at all of the time points and significantly better than passive recovery. This could be especially advantageous for athletes who for whatever reason are unable to undergo an active cool-down after training or competition. Similar measurements of reduced muscle damage markers when wearing compression clothing have been obtained from studies on two sets of eccentric action arm curl exercises in untrained women6 and in men7. In both cases, post-exercise swelling and soreness were reduced and the subjects were also able to increase the rate of recovery in force production in the second set.
Does compression clothing hinder certain aspects of exercise performance?
Power-lifters have long used extreme compression wraps around certain joints for stability and to enhance 1-rep max lifting capability. The levels of compression used in the new generation of compression clothing is much lower, but there exists the possibility that even small amounts of external resistance from this type of clothing could add to energy costs of higher rep and endurance exercise, and so hinder performance.
To investigate this US scientists measured the external resistance produced by compression clothing during 3 sets of 50 knee extension/flexion movements and squatting at 70% of 1-rep max8. They concluded that the levels of compression typically provided by compression clothing were not detrimental to force production or to the energy costs during extended work in the muscles involved. In fact, the opposite may even be true as other studies have indicated that compression shorts and tights can assist the eccentric action of the opposing muscles (eg in the hamstrings when running, at the end of the recovery phase)2,9. Moreover, yet more studies have indicated that compression clothing may even enhance exercise performance via increased cooling as a result of an increased transfer of sweat from the skin to the surface of the clothing where evaporation can take place10.
Far from being a mere fashion accessory, the evidence suggests that compression clothing can enhance performance and recovery in vigorous exercise via reduced muscle oscillation and increased proprioception and modification of lactate transport. Compression clothing also has the advantage of being easy to use, relatively inexpensive and legal. However much research remains to be done on the optimum levels of compression for different sporting requirements, so watch this space!
1. J Sport Con Res, 1996; 10, 180-183
2. J Sport Sci, 2003; 21, 601-610
3. Int J Sports Med, 2006; 27, 373-378
4. Am J Physical Med, 1987; 66, 121-132
5. Br J Spts Med, 2006; 40, 260-263
6. J Sports Rehab, 2001; 10, 11-23
7. J Orthop Spts Phys Ther, 2001; 31, 282-290
8. J Sport Con Res, 1998; 12, 211-215
9. Sports Med, 1997; 23, 397-404
10. Eur J Appl Physiol, 1998; 78, 487-493
Original article by Andy Harrison and Kevin Thompson
Summary by Andrew Hamilton BSc Hons MRSC ACSM