Compression clothing and blood lactate Andy Harrison BSc, MSc is a physiologist who works as athlete services manager for the English Institute of Sport Kevin Thompson PhD is a physiologist who works as regional manager for the English Institute of Sport The favorable effects of compression clothing on the muscle pumping action of the cardiovascular system have led scientists to speculate whether increases in venous return could assist in the removal of blood lactate from exercising muscles. In one of the first exercise-related trials, scientists tested six male college students to determine the effects of wearing compression stockings on exercise response(4). The students completed both a treadmill (VO2max test) and bicycle ergometer (3 separate 3-minute bouts at 110% of their VO2max) assessments. The results from both tests showed a decrease in post-exercise lactate concentration when the compression clothing had been worn during the exercise. The investigators concluded that the compression stockings were increasing the lactate retained in the muscles, thereby reducing the amount released into the blood. The garments used in the above studies are commercially designed for long-term wear in sports and training. It is common practice, however, for power lifters to use tightly bound wraps around various joints of the body to enhance force production. Anecdotally, the use of ‘super-suits’ in power lifting appears to enhance high force development for 1RM lifts. Such ‘suits’ are considered extreme compression as lifters can only tolerate them for short periods. The level of compression exerted by the garments discussed in this article is much lower. A team of American scientists investigated whether even this lower level of compression added a significant external resistance to the actions of the contracting musculature whilst exercising(5). Active subjects were asked to complete isokinetic knee extension/flexion movements (3 sets of 50 maximal efforts) and their maximal number of squats (at 70% 1RM). The primary finding from the study was that the comfortable compression levels found in the commercial garments did not have a negative effect on force production or total work capacity of the thigh muscles. This study suggests that the use of commercially available compressive shorts does not add any significant amount of resistance to repetitive muscle actions, that would add an additional fatigue factor leading to diminished performance. In fact, other studies have reflected that any small opposing torque may reduce injury by assisting the action of the hamstrings, eg at the end of the recovery phase whilst running(2,6). Further injury prevention may be afforded by compression clothing via the reported reduction in muscle oscillation on landing from a jump(2). In addition to the above, there is evidence to suggest that compression clothing may improve exercise performance by reducing the impact of hot and/or humid conditions on the body’s thermoregulatory system(7). It is well documented that heat strain as a result of an elevated core body temperature can cause a reduction in exercise performance. In humans, the primary means of cooling the body during exercise is through the evaporation of sweat from the skin surface. Increases in skin and core temperature and a reduction in cooling efficiency are observed when clothing interferes with the evaporation of sweat from the skin. It has been suggested that compression clothing assists the rate of evaporation by facilitating a faster transfer of sweat from the skin to the fabric. Once there, the sweat can be transported through the fabric and dispersed more quickly and evenly over a larger area allowing evaporation to be maximised. If this is the case then athletes would feel cooler during exercise and perceive the activity as being less difficult. -Dr. K
Posted on: Tue, 13 Aug 2013 20:45:49 +0000
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