engleski

Are acute effects of maximal dynamic contractions on upper-body ballistic performance load specific?

This study investigated the acute effects of upper-body maximal dynamic contractions on maximal throwing speed with 0.55 kg and 4 kg medicine balls. It was hypothesized that heavy preloading would transiently improve throwing performance only when overcoming the heavier of the two loads. Twenty-three male volunteers were randomly allocated into experimental (n=11) and control (n=12) groups. Both groups performed initial and final seated medicine ball throws from the chest and the maximal medicine ball speed was measured by means of a radar gun. Between the two measurements, the control group rested passively for 15 min, while the experimental group performed 3 sets of 3 repetition maximum bench presses. For the 0.55 kg load, a 2 × 2 repeated measures analysis of variance (ANOVA) revealed no significant effect of time × group interaction (P = 0.22), as well as no significant time (P = 0.22) or group (P = 0.72) effects. In contrast, for the 4 kg load, a significant time × group interaction (P = 0.004), as well as a significant time (P = 0.035), but not group (P = 0.77) effect was observed. Analysis of simple main effects revealed that the experimental group significantly (8.3% ; P < 0.01) improved maximal throwing speed with the 4 kg load. These results support our research hypothesis and suggest that the acute effects of heavy preloading on upper-body ballistic performance might be load-specific. In practical sense, our findings suggest that the use of upper-body heavy resistance exercise prior to ballistic throwing movements against moderate external loads might be an efficient training strategy for improving athlete’ s upper-body explosive performance.

complex training ; postactivation potentiation ; muscle power ; throwing

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