Stretching: Acute Effects on Strength and Power Performance

Strength and Conditioning Journal February 2000 STRETCHING (FLEXIBILITY TRAINing) has long been part of the warm-up routine for athletes. The use of stretching as part of the warm-up comes from the belief that stretching will aid in subsequent performance and help prevent injury. The type and degree of stretching used as part of a warmup routine varies among sports. Our observations of many strength/ power athletes (including elite weightlifters, powerlifters, track and field throwers, etc.) suggest that many of these athletes do little in the way of general stretching (especially the agonist muscle groups) or general warm-up. The pre-event and prepractice routines of these athletes consist more of sport-specific exercises done with light resistance and/or low velocity, slowly building up to full effort. This contradicts the suggestions of Arnheim (1), who states, “general warm-up procedures should consist of jogging or easy running, gradual stretching, and general exercises. These procedures should mobilize the body for action and make it supple and free. ” Many athletes and coaches also believe that light aerobic exercise augments the results of stretching. There is little empirical evidence that shows that warming up by light exercise (i.e., jogging) before stretching will significantly increase flexibility (20). The purpose of this paper is to examine the research considering the acute performance effects of stretching. Although little stretching typically takes place in the warm-up for strength/power sports, most of these sports (especially weightlifting) require a high degree of flexibility. In fact, many of these athletes do stretch both dynamically and statically. Most of the static stretching occurs immediately after workouts or competitions. As stated by Taylor et al. (17), “the extensive interest in stretching and the widespread use of stretching techniques in athletes, the arts, and general fitness programs are contrasted by the paucity of basic science information on stretching. ” Along with this lack of general information, few studies examined performance effects of stretching during warmup for strength/power athletes. There are, however, some theories that can be proposed from studies examining the effects of stretching on muscular properties. Changes in muscle contraction following stretching are likely caused by changes in the mechanical properties of the muscle/tendon unit or by changes in enervation and neuromuscular transmission. This article will concentrate on the acute mechanical effects of stretching. Muscle stiffness can be decreased with warm-up and stretching (11). The stiffness of a muscle is defined as the ratio of a change in force divided by the change in the length of the muscle during stretching (7). While a more compliant muscle-tendon unit may decrease injury potential (11), a decreased stiffness in the agonist may reduce power output and force production by somehow affecting the myototic reflex or the elastic properties of the muscle. Decreased stiffness may be associated with an increase in flexibility, but no change in muscle stiffness © National Strength & Conditioning Association Volume 22, Number 1, pages 44–47