THE EFFECTS OF BARBELL LOAD ON COUNTERMOVEMENT VERTICAL JUMP POWER AND NET IMPULSE

The aim of this study was to examine the effects of barbell load on countermovement vertical\ud jump (CMJ) power and net impulse within a theoretically valid framework, cognisant of the\ud underpinning force, temporal, and spatial components. Twenty-four resistance-trained rugby\ud union athletes (average ± SD: age: 23.1 ± 3.4 yrs; height: 1.83 ± 0.05 m; body mass: 91.3 ±\ud 10.5 kg) performed maximal CMJ under five experimental conditions in a randomised,\ud counterbalanced order: unloaded, and with additional loads of 25, 50, 75 and 100% of body\ud mass (BM). Peak power and average power were maximised during the unloaded condition,\ud both decreasing significantly (p < 0.05) as load increased. Net impulse was maximised with\ud 75% of BM, which was significantly greater (p < 0.05) than the unloaded and 100% of BM\ud conditions. Net mean force and mean velocity were maximised during the unloaded condition\ud and decreased significantly (p < 0.05) as load increased, whereas phase duration increased\ud significantly (p < 0.05) as load increased. As such, the interaction between barbell load and\ud the underpinning force, time and displacement components should be considered by strength\ud and conditioning coaches when prescribing barbell loads