Compression garments unproven, but athletes say they boost performance
Despite a lack of scientific evidence, pressure garments are becoming increasingly popular with athletes of all abilities, writes Jeanette Wang
Can socks really make you faster? Judging from the field at the Ironman World Championships in Hawaii two weekends ago, many of the world's fittest athletes - sporting knee-high socks or calf guards - seem to think so.
It's a look that would make Pippi Longstocking proud, and the fashion police cringe. But these aren't just any socks. They're made of special body-hugging fabric that exerts various degrees of pressure along the limb. This is said to improve blood circulation and reduce the wobble in muscles and tendons that occurs during repetitive exercise, resulting in reduced muscle pain and fatigue, and enhanced performance and recovery.
Compression garments were initially only worn by performance-seeking elite athletes. But in recent years, they have become a wardrobe staple among fitness enthusiasts of all abilities.
There has been a real increase in the number and type of compression garments on offer - from socks to tights and tops - and more brands are making an appearance in Hong Kong. Sales have been going up, too, according to several local sports shops.
"We've seen a significant increase in the popularity of compression garments, especially over the past 18 months," says Bruce Pye, managing director of Sports World, which began selling compression garments in late 2010. "This, of course, boils down to marketing and education," he says.
Kirsty Hulme, managing director of Sure Step Asia Pacific, exclusive Hong Kong distributors of Australian athletic apparel 2XU, says the brand's sales in Hong Kong have been increasing 50 to 60 per cent year on year, driven by the growth in sales of compression garments.
The 2XU compression range, tested by the Australian Institute of Sport, has expanded from about five styles in 2009 to more than 100 at present, thanks to the recent introduction of a new coloured compression line. Hulme says the launch of this vibrant range is a sign that the leisure market has caught on to compression garments, and indicates an increasing understanding and appreciation for the benefits of this type of clothing.
Runners and triathletes aren't the only ones wearing them either. Rowers, fencers, racquet sport players, basketball players, golfers, soccer and rugby players are also sporting them - and, Hulme says, even ladies who brunch.
Compression garments are not new. They've been used in the medical field for more than 50 years for treatment of poor blood flow in post-surgery patients, says Lo Ka-kay, senior sports officer with the Hong Kong Sports Institute.
"The compressive effects of these garments are used to improve recovery by promoting venous blood flow, decreasing venous stasis and preventing thrombosis in post-operative patients," she says.
Compression stockings have also been recommended for sufferers of deep vein thrombosis to prevent blood clotting during long-haul flights.
However, when it comes to enhancing athletic performance, studies have produced mixed results.
University of Oxford researchers did an extensive review of studies on compression garments. In their report, "Mythbusting Sports and Exercise Products", in last year's BMJ (formerly the British Medical Journal), they concluded: "There is a lack of evidence to support use of compression garments to improve sporting performance.
"Muscle soreness seems to be reduced if garments are worn for 24 hours after exercise, but objective measures of recovery are less consistent, and compression garments seem to work no better than other recovery strategies such as low grade exercise or contrast bathing."
In a more recent review, German sports scientists from the University of Wuppertal report in the International Journal of Sports Physiology and Performance that compression clothing had "small effect sizes" during exercises for short-duration sprints (10 to 60 metres), vertical jump height, extending time to exhaustion, and time trials (three to 60 minutes).
There were "small to moderate effect sizes" in recovery of maximal strength and power, reductions in muscle swelling and perceived muscle pain, blood lactate removal and increases in body temperature.
Not all compression garments are equal. They come in different fabrics, knits, pressures and styles. Should you go for waist-to-ankle tights or the short style that ends above the knee? For the calves, do sleeves or socks work better? And which brand should you buy?
Lo says it's possible that in studies that found no benefit of compression garments, the pressure of the elastic tights may not have been sufficient. Conversely, if the pressure is too high it could impede blood flow to muscles during exercise and cause discomfort.
"It seems the tensile force of the compression garment must be optimised for enhanced performance and recovery," she says.
But Lo adds that most studies do not specify the pressure of the compression garment in different body areas, and that makes comparing results difficult. The Hong Kong Sports Institute process of studying the ideal pressure of compression garments for different areas of the lower body, for athletes of different sports and for performance and recovery.
"Performance and physiological indicators such as exercise economy, lactate reduction at prolonged sub-maximal speed, rate of perceptions of muscle soreness and thermal sensation are measured during exercise and recovery period with or without use of compression garments," says Lo.
"We are still processing the data, but preliminary feedback is positive."
Whatever the science proves, if you believe that compression works, then it may very well work for you.
In a 2010 study, Abigail Laymon, a researcher at Indiana University's department of kinesiology, put 16 highly trained male distance runners through a treadmill test to ascertain the benefits of lower leg compression.
It turned out that the subjects who experienced improvement in their running economy while wearing the compression garment were more likely to have a favourable attitude towards compressive wear. They believed that by wearing the garment, they performed better.
"Overall, with these compressive sleeves and the level of compression that they exert, they don't seem to do much," Laymon says.
"However, there may be a psychological component to compression effects. Maybe if you have this positive feeling about it and you like them, then it may work for you. It is a very individual response."
Newly crowned Ironman world champion Frederik Van Lierde seems to believe in it, even though pulling on his compression calf guards after the opening 3.8-kilometre swim cost him precious time. The Belgian eventually powered through the 180-kilometre bike ride and 42.2-kilometre run to win the Hawaii race in 8:12:29.
Andrew Dawson, a Hong Kong trail runner, uses compression tights and calf guards while running, and compression socks under his workwear to aid recovery the day after a long run.
"From what I've read, there's a lack of scientific studies on compression gear, but my theory is that it can't do anything bad, so I may as well give it a go," he says. "I do tend to feel better when I've worn compression socks for recovery."