Sports compression garments: the expectations vs the evidence
Research suggests that compression garments can be effective for improving muscle recovery after fatiguing exercise, but has shown little to indicate an athletic performance benefit.
A World Cup soccer player, a National Basketball Association point guard, a National Football League wide receiver, an Olympic gold-medal-winning short-track speed skater, a mixed martial artist, a professional wake-boarder. These are examples of elite-level athletes who wear compression garments with expectations of enhanced performance or muscle recovery.
These expectations are driven by compression gear companies who target professional and recreational athletes alike with website messages advising that the products will “take their sports performance and recovery to the next level,” as one site puts it. Published studies of compression garments, however, don’t fully support these claims.
In theory, sports compression garments improve performance during exercise and speed recovery afterward by improving vascular circulation, thus increasing oxygen delivery to muscles and removal of metabolic waste products such as lactic acid.
Research does indicate that compression can be effective for improving muscle recovery after fatiguing exercise, such as running a marathon. But, although multiple studies have looked at the effect of compression garments on sports performance, they have found little evidence of a performance benefit. And some researchers have found that the advantages of the garments primarily have to do with the wearer’s perception—raising the possibility of a placebo effect.
The degree to which marketing impacts the wearing of compression garments cannot be underestimated, according to Australian researchers in human movement science.
“There is little doubt that sports compression garments exploded on the scene and the ‘trend’ grew much faster than the scientific evidence,” said Peter Clothier, Ph.D, a lecturer in the School of Science & Health at the University of Western Sydney in Australia. “As with many trends in sports performance, the onus on the usage of devices such as compression garments is an individual one.”
Focusing on fit
The question of fit, or more specifically, the degree of compression provided by compression garments, is a common issue that has been raised in the peer review process and literature regarding the variable results. Specifically, a large majority of studies have not measured the exact amount of compression participants are receiving.
Experts say the fit is fundamental: If compression is not optimized, then the garment can’t do what it is proposed to do, regardless of whether that compression can actually make any physiological difference to an athlete. “It is possible that there may be an optimal degree of pressure that elicits beneficial or better effects,” Clothier said. “However, there is a lack of a valid and reliable scientific method to measure the pressure at the garment-skin interface. Several studies report attempts to quantify the degree of compression. However, these studies often fail to report the reliability of these measurements. Attempts to measure compression have occurred at a small number of easily accessible sites that are not representative of the net compression over the entire limb.”
Amitabh Gupta, PhD, a lecturer in Allied Health at the University of Western Sydney in Australia who coauthored a study on compression garments with Clothier, said a valid and reliable system would need to be developed to accurately measure total limb compression.
“To date, there are no such systems available,” Gupta said. “Therefore, the approach in our study1 was to follow manufacturer guidelines, which are the only method a consumer has to purchase an appropriately fitting garment.”
Jessica Hill is a PhD candidate studying recovery from muscle damage in endurance exercise and a sport and exercise physiology senior lecturer in the School of Sport, Health and Applied Science at St. Mary’s University in Twickenham, UK. She was the lead author on another compression garment study that appeared earlier this year in International Sports Engineering Association.2 The study addressed the variation in pressures exerted by commercially available compression garments.
“There was large variability in the way that the compression garment fits an individual,” Hill said. “They will not all be getting the same amount of compression. For me the biggest issue surrounding compression is whether the garment fits, and unfortunately, unless an athlete goes bespoke, it is going to be difficult to know if the garment fits properly. The fit of the garment is likely to be an important factor in how effective the garments are.”
Clothier and his colleagues studied the effect of compression garments on motor performance parameters and leg mechanical characteristics during rapid and repeated loading of a limb to exhaustion—a lower limb dynamic rapid loading task that utilized the stretch-shortening cycle.1
They assessed 38 recreationally active male participants with a mean age of 22 years who performed single-leg, on-the-spot hopping at a frequency of 2.2 Hz for up to three minutes or to volitional exhaustion. Biomechanical measures included total duration of hopping time and individual hop cycle characteristics, including spatioÂtemporal variables and leg mechanics.
Each participant was tested under three conditions—garment, sham garment, and no garment—with the order of conditions randomized. The sham garment was designed to look and feel like the compression garment but did not actually provide compression.
Flight phase and contact phase duration, vertical displacement of the center of mass during the flight phase, and normalized vertical leg stiffness all were significantly different at the end of the hopping trial than at the start. However, there were no significant differences between conditions for any of the variables measured. The researchers concluded that commercially available compression garments, when fitted to manufacturer guidelines, did not enhance performance in a controlled, relatively short duration hopping task to exhaustion, compared with no garment and the sham garment.1
“There was also no influence of [the compression garment condition] on performance of a number of biomechanical measures as described by spatiotemporal characteristics and vertical stiffness,” Gupta said.
While compression garments did not improve performance, they also did not detrimentally affect performance, the researchers noted. Therefore, they said, the choice to use compression garments must be made based on the perceived cost-to-benefit ratio.
“The perceived benefits, such as comfort, may still sway the choice of whether to use a compression garment or not during their performance,” Gupta said. “This study did not demonstrate a change in leg mechanical characteristics, and interestingly did not demonstrate an increase in the duration of hopping. Although not surprising, it does add to the view that compression garments may not directly improve motor performance, however, and plausibly, they may play a role in comfort and recovery.”
Despite the lack of research supporting compression garments as performance enhancers, their popularity has been likened to the widespread appeal of kinesiology tape among athletes.
“The use of compression garments during sport is similar to the fashion of Kinesio tape,” said Stuart Armstrong, MD, a sports and exercise physician with Anglesea Sports Medicine in Hamilton, New Zealand, alluding to the fact that manufacturer claims about the physiological effects of elastic therapeutic tape also have proved difficult to substantiate (see “Elastic therapeutic tape: The search for evidence,” March 2015, page 37).
Possible placebo effects
Armstrong, like others who have studied the sports application of compression garments, said that any performance benefit is an imagined one.
“It will have a placebo effect if [athletes] believe it is helping their game, but there is no clinical evidence above and beyond this,” he said.
Scientists have said the challenge of blinding participants makes conducting studies on compression garments difficult, if not impossible. This leaves open the possibility of a placebo effect when measuring variables like subjective responses (eg, perception of muscle soreness) or subsequent exercise performance.
“That said, if evident, a positive effect is a positive effect,” said researcher Braid MacRae, MSc, who published a study on compression garments and exercise in Sports Medicine in 2011 while with the University of Otago in Dunedin, New Zealand.3 MacRae, who is currently with the Swiss Federal Laboratories for Materials Science and Technology (Empa) in St. Gallen, Switzerland, said the placebo effect should not be discounted.
“I think it would be foolish to overlook a placebo effect as an effect,” MacRae said. “If what you’re after is getting out the door for your next training session, and wearing compression garments helps do that, then I don’t see anything wrong with that. My advice for athletes would be quite practical. I believe you shouldn’t underestimate personal experience.”
Researchers in the US and abroad expressed similar positions.
“While it doesn’t appear that there are quantifiable physiologic changes when you wear [compression] garments, anecdotally, people do feel better and more confident when they wear them,” said Samuel R. Ward, PT, PhD, who is a professor in the departments of radiology, orthopaedic surgery, and bioengineering at the University of California, San Diego in La Jolla. “They feel like they have more support around something that was either injured or they feel as though it’s predisposed to injury. I think many people downplay the second part of that, which is not right. There’s a significant component of performance that is between your ears—the better people feel, the better they’re going to perform.”
Evidence for muscle recovery
Despite the lack of evidence for performance enhancement, the research has generated some evidence of beneficial effect in terms of muscle recovery. Armstrong, in fact, was the lead author of a randomized controlled trial of compression socks and their effects on functional recovery following marathon running that appeared last year in the Journal of Strength and Conditioning Research (JSCR).4
The compression garments came up to the knee and had a moderately strong compression gradient. They were fitted to 33 uninjured experienced maraÂthon runners based on shoe size and calf girth.4
“Essentially, my research showed that there is a benefit in the use of compression garments for recovery after an exhaustive sporting event,” he said. “Crucially, the compression garments weren’t worn during activity, but were worn following the completion of activity.”
The aim of the study was to show whether compression socks worn for 48 hours after running a marathon could improve functional recovery 14 days later. The runners were measured by a timed treadmill test to exhaustion two weeks prior and two weeks following each marathon. The group wearing the compression socks, which were designed to give a compressive value between 35 and 45 mm Hg when fitted per the manufacturer’s instructions, increased the runners’ time to exhaustion by 2.6%. The placebo group, wearing the sham garment—a no-seam diabetic sock designed to be in the 4- to 5-mm Hg range (enough comÂpression to keep the sock up)—decreased their time by 3.4%.4
“I was surprised I was actually able to show a difference in running performance two weeks following a marathon in the compression group versus the noncompression group,” said Armstrong, who noted that compression garments need to be medical grade rather than fashion-accessory grade. He recommended a level between 35 and 45 mm Hg for athletes. He also noted the importance of fit.
“Fit of the garments is incredibly important, and I know from the study I did, even though the compression socks were fitted to the participants, they were off the shelf and there was a wide variety of actual compressive values obtained in the athletes,” he said.
Another study investigating the effects of compression on recovery following marathon running indicated perceived lower levels of muscle soreness. Hill was the lead author on the study that appeared last year in JSCR.5
“Compression garments appear to reduce the severity of symptoms associated with muscle damage and have been indicated to accelerate recovery of muscle function,” she said.
Twenty-four runners were divided into two groups. One group wore lower limb compression tights for 72 hours after completing a marathon. The other group received one 15-minute treatment of sham ultrasound after the marathon. Perceived muscle soreness, maximal voluntary isometric contraction (MVIC), and serum levels of markers for muscle damage (creatine kinase [CK] and C-reactive protein [C-RP]) were assessed at various points. Perceived muscle soreness was significantly lower in the compression group than the sham group 24 hours after the marathon. There were no significant group effects for MVIC, CK, and C-RP.5
The study concluded that, while the use of a lower limb compression garment improved subjective perceptions of recovery, there was neither a significant improvement in muscular strength nor a significant attenuation in markers of exercise-induced muscle damage and inflammation.5 The other factor Hill said should be noted is that the individuals who took part in this study were experienced runners completing high weekly training volumes. Therefore, they were unlikely to experience very high levels of muscle damage, even after a marathon, and were likely to recover more quickly than less intense runners.
“If we had used a more inexperienced group of individuals we may have found different results,” Hill said. “We conducted a systematic review and meta-analysis of studies investigating the efficacy of compression and identified that the use of compression appears to reduce the severity of symptoms associated with exercise-induced muscle damage following strenuous exercise.”
That meta-analysis was published in the September 2014 issue of the British Journal of Sports Medicine.6 Hill and her researchers used an electronic search of the literature, ending in August 2012. They used three online databases (MEDLINE/PubMed, SportDiscus, and ISI Web of Knowledge) using a combination of terms.
Caveats and considerations
While sports compression garments aren’t a magic bullet and likely won’t help an athlete run faster or jump higher, they may enhance performance through perceived benefit and they may help in recovery.
“As a general rule in medicine, particularly in orthopedics, when people have pain or instability, compression provides some improvement in symptoms,” Ward said.
Additionally, Clothier and Gupta pointed out that, while their study concluded compression garments did not promote performance in a controlled short-duration hopping task, their findings did not necessarily translate into a lack of efficacy.
“In no way do we suggest that the wearing of commercially available [compression garments] could not enhance sporting performance, especially in relation to other movements, sporting activities or from a thermoregulatory, neuromuscular, physiological, or psychological perspective,” Clothier said.
He added that, because it’s possible that garments may affect other parameters than those measured, it is also plausible that the reported benefits of garments involve aspects of motor performance that do not directly relate to biomechanics.
By P.K. Daniel, Lower Extremity Review - August 2015