Abstract

Background/Objectives: The purpose of this study was to compare differences in positive lower limb joint work contributions during the concentric phase of the countermovement jump (CMJ) at various levels of perceived effort (PE). Methods: Twenty-four recreationally active individuals (12 males: age = 23 ± 5.0 y, weight = 83.8 ± 14.5 kg, height = 1.8 ± 0.1 m; 12 females: age = 23 ± 2.0 y, weight = 62.6 ± 12.0 kg, height = 1.6 ± 0.1 m) completed fifteen CMJs while kinematic and ground reaction force data were obtained. Jump height (JH), lower limb total work (Wtotal), and individual ankle (%ankle), knee (%knee), and hip (%hip) joint work contributions were calculated for 100% (PE100), 75% (PE75), 50% (PE50), and 25% (PE25) perceived effort jumps. Results: One-way repeated measures ANOVA tests (α = 0.05) indicated JH and Wtotal were significantly different across all perceived effort levels. The %ankle increased significantly as PE decreased, and %hip decreased significantly as PE decreased. The %ankle and %hip were not significantly different between PE50 and PE75 conditions, and %knee did not differ across PE levels. Conclusions: Reducing PE altered lower limb joint work contributions during the concentric phase of the CMJ by increasing %ankle and decreasing %hip. In addition, decreases in PE did not correspond proportionally to reductions in JH or Wtotal, suggesting that effort does not map linearly onto mechanical output during the CMJ.

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