The effects of various durations of maximal voluntary isometric contractions on subsequent power performance
Date
2002
Authors
King, Adrian John Clinton
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Abstract
The purpose of this study is to 1) determine if a 2.5, 5, and 10 s maximal voluntary isometric contraction (MVIC) in the form of a squat can produce post-activation potentiation (PAP) and enhance subsequent squat jump (SJ) performance 2) determine if there is a relationship between MVIC duration and the degree of enhancement of SJ performance and 3) determine the persistence of the PAP phenomenon. Eleven physically active male subjects participated in this study and randomly completed four separate testing conditions. The three different durations of MVIC and a control condition (no MVIC) were performed on different days separated by at least 48 hours. Within each testing session, one set of five squat jumps were performed 15 min before and 4 and 6 min after a MVIC on a Kistler force platform. Jump height, ground reaction force, time to peak force, and impulse were derived from the force platform and analyzed. The 10 s MVIC produced significant decreases in SJ height 6 min following the contraction. The 10 s MVIC also produced significant decreases in impulse 4 and 6 min following the contraction. No other significant changes in any of the force plate data were observed. It is concluded that 2.5 and 5 s MVIC in the form of a squat were unsuccessful in producing a PAP of SJ performance and a 10 s maximal isometric squat may be detrimental to performance.