sábado, 23 de julio de 2011

Journal of Strength and Conditioning Research

Effects of Plyometric Training and Recovery on Vertical Jump Performance and Anaerobic Power.

1Health and Human Performance Laboratory, Virginia Commonwealth University, Richmond, Virginia 23284; 2Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27858; 3University of Kansas, Department of Health, Sport and Exercise Sciences, Lawrence, Kansas 66044.

The ability to produce explosive lower-body power can be an important factor in the performance of many athletic activities. Sports that require jumping, throwing, or sprinting rely heavily on the strengthspeed or power of the athlete (1, 3, 19, 22). Plyometrics are used to improve power output and increase explosiveness (1) by training the muscles to do more work in a shorter amount of time (12). This is accomplished by optimizing the stretch-shortening cycle, which occurs when the active muscle switches from a rapid eccentric muscle action (deceleration) to a rapid concentric muscle action (acceleration; 14, 19, 22).

The rapid eccentric movement creates a stretch reflex that produces a more forceful concentric muscle action (14, 22) than could otherwise be generated from a resting position (19). The faster the muscle is stretched, the greater the force produced, and the more powerful the muscle movement (5, 22). Plyometric exercises that exploit the stretch-shortening cycle have been shown to enhance the performance of the concentric phase of the movement (8) and increase power output (11). Traditionally, plyometric exercises include variations of bounding, hopping, and jumping drills. However, true plyometric training requires the rapid prestretch (eccentric movement) of the muscle and maximal effort of the athlete during the concentric muscle action. This type of plyometric training can be found in various forms of depth jumps and box jumps (14).

The effects of plyometric training on performance enhancement have been studied for several years. The literature spans a wide variety of assessments, including the effects of plyometrics on athletes and nonathletes (22), on aerobic performance (19), and on muscle fiber size (19), as well as its effectiveness as a standalone training program (6, 22) or as part of a combined program concurrent with aerobic training (19); resistance training (5, 6, 23); or electrostimulation (18). Research has found plyometrics to be effective in increasing muscle power output (12) and vertical jump performance (24).

To our knowledge, no studies have addressed the effects of different durations of a plyometric training program on improvements in power output. From a training perspective, it is important to determine the appropriate training duration necessary to elicit peak athletic performance. We also want to know if the absence of plyometric training during a recovery period would influence vertical jump performance and anaerobic power. The purpose of this study was to determine the effects of a 4-week and a 7-week plyometric training program followed by a 4-week recovery period of no plyometric training on vertical jump performance and anaerobic power.
Journal of Strength and Conditioning Research, 2003, 17(4), 704–709 
(c) 2003 National Strength & Conditioning Association.

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