After engaging in physical activity, especially strenuous exercise, athletes at various levels of performance will often squeeze into super-tight “compression” garments – be they shorts, knee-high socks, sleeves, tops or tights – in an effort to boost performance and facilitate recovery. It is proposed that compression garments work by compacting the surface of the skin, thereby increasing blood circulation, which helps to deliver more oxygen to working muscles while enhancing the removal of waste by-products and muscle metabolites. As a consequence, companies like Skins, Under Armour and 2XU have blossomed as compression gear manufacturers, often claiming their products will improve recovery, increase muscular power and improve endurance in a variety of sports. Recently, a number of publications have reported contradictory results with regards to the influence of compression garments on these parameters, which raises an important question: can compression garments worn during and after exercise really aid recovery and/or enhance athletic performance?
Athletic training and competition frequently result in exercise-induced muscle damage (EIMD). The degree of this muscle damage depends on the exercise type, duration, intensity and habituation to exercise.1 Furthermore, exercise with an eccentric component, where the muscle lengthens while under tension, results in a greater magnitude of EIMD. This is due to the inflammatory response resulting from the mechanical damage or small tears caused to sarcomeres during eccentric loading. EIMD is characterised by symptoms such as temporary reduction in muscle strength, decreased rate of force development, reduced range of motion, swelling, increased feeling of soreness and the appearance of intracellular proteins in the blood.1
These symptoms can last for several days and may affect the capacity to train at the desired intensity in subsequent sessions or impact on competition performance. As a result, methods to reduce the negative symptoms associated with EIMD are widely sought by athletes.
How Does Compression Work?
Modern-day compression attire has evolved from medical practices, where compression garments are frequently used to treat clinical pathologies. Usually worn over the leg and foot, medical compression stockings have been used to control oedema or swelling, promote venous blood flow and prevent post-operative thrombosis for more than 50 years.2 This is achieved by creating a controlled gradient compression force to the leg (ranging from 20-40 mmHg), typically greatest at the ankle and diminishing over the length of the leg. The use of compression garments in sport has become increasingly popular due to claims they can improve recovery from strenuous exercise by creating an external pressure gradient, thus reducing the space available for swelling.1 More specifically, the principle of compression therapy is based on Laplace’s equation, which states that the pressure is directly proportional to the amount of tension and the number of layers applied and inversely proportionate to the limb circumference and width of material applied. As such, it has been shown compression garments require a minimum pressure of 18mmHg at the ankle and 8mmHg at the mid-thigh to mimic the hemodynamic effects of exercise and increase venous return.3
Compression Garments and Recovery
A recent meta-analysis examined the effects of compression garments on recovery from EIMD. The data of 12 studies with a combined number of 205 athletes (n = 136 men and n = 69 women) was reported. The results indicated compression garments are effective in enhancing a more rapid recovery in muscle function, muscle soreness and blood markers of muscle damage. Specifically, the results, which were obtained through the use of a visual analogue scale or Likert scale, showed the use of compression garments had a moderate benefit in reducing the experience of delayed onset muscle soreness (DOMS). It is suggested up to 66 per cent of athletes are likely to experience reduced DOMS with compression. Similarly, a moderate effect on recovery muscle strength (including measurements of isometric, isokinetic and isotonic muscle contractions) and explosive muscle power post-exercise was also recorded. The review demonstrated performance measures of strength and power recover at a faster rate in up to 69 per cent of athletes with the use of compression garments post-exercise.1 Creatine kinase (CK) obtained from capillary or venous blood is used extensively as a marker of muscle damage. The use of compression garments had a moderate effect on the reduction of CK post-exercise. Such reductions in CK observed with compression garments have been attributed to improved clearance of metabolites and enhanced repair of muscle.1
A group of Australian and New Zealand researchers set out to determine whether wearing below-knee compression socks for 48 hours immediately after running a competitive marathon would improve functional recovery as measured by a timed treadmill test to exhaustion 14 days following the event. Athletes participating in the Melbourne, Canberra and Gold Coast marathons in 2012 or 2013 were recruited and randomised into either the compression sock or placebo group.4 Participants (n = 33) completed maximal treadmill tests to exhaustion two weeks before and two weeks after their marathon. In the compression sock group, treadmill run to exhaustion time was increased by 2.6 per cent compared with a decreased treadmill run to exhaustion time (3.4 per cent) in the placebo group. The authors suggested the athletes in the compression sock group experienced better recovery within the 48 hours post event, which subsequently enabled them to perform better during the treadmill test.
Compression Garments and Running Performance
From the evidence, it appears compression garments have a positive impact on recovery variables, but what does the research say about running performance? According to a recent systematic review, compression garments had little or no positive effect on racing performance as reflected in times for marathon, half marathon, 15km, 10km, 5km and 400m events. Furthermore, physiological parameters such as maximal and submaximal oxygen uptake measured from a laboratory test, blood lactate concentration, cardiac parameters (including heart rate, cardiac output, and stroke volume) and body temperature were also unchanged by compression garments.5 In contrast, wearing compression garments saw improvements in running economy and biomechanical variables (i.e. ground contact time, step frequency, step length and swing time), enhanced clearance of blood lactate, improved psychological variables (including perceived exertion) and a reduction in markers of muscle damage (CK) and inflammation. The largest positive effect reported with the use of compression garments was reduced perceived muscle soreness and markers of inflammation post exercise.5 These findings show some research indicates compression garments may provide an ergogenic benefit during exercise and that others have been unable to support these findings. Importantly, as no studies have reported negative effects on exercise performance or perception of pain, the use of compression garments may provide a useful training tool for athletes across a wide variety of sports.2