Purpose: To analyze the effects of different inertial loads on power production and power maintenance, as well as the number of sessions required for proper familiarization during the flywheel quarter-squat.
Methods: Twenty-four high-level handball players attended 4 testing sessions consisting of 4 sets of 10 repetitions using 4 different inertial loads (0.025, 0.050, 0.075, and 0.100 kg·m2). In addition, a 5th set of 15 repetitions was performed. Both concentric and eccentric peak power and the eccentric:concentric ratio were recorded.
Results: The results showed the need to perform 3 sessions for a proper familiarization (ie, outcomes stabilization). The inertial load of 0.025 kg·m2 led to greater concentric peak power compared with the other inertial loads (from likely to most likely greater values). Both 0.025 and 0.050 kg·m2 inertial loads entailed greater eccentric peak power compared with 0.075 and 0.100 kg·m2 (most likely greater). Conversely, the 0.025-kg·m2 inertial load showed a lower eccentric:concentric ratio, presenting negative effects (most likely lower values) compared with the inertial loads of 0.050, 0.075, and 0.100 kg·m2. Participants were able to perform 5-12 repetitions per set without significant peak power output decrements.
Conclusions: This study highlights the importance of performing at least 3 sessions to obtain a stable measure during flywheel squat exercise. Lower inertial loads (0.025 kg·m2) are the better option for eliciting high concentric peak power output values. In contrast, medium to high inertial loads are more appropriate to achieve greater eccentric overload values.
Keywords: eccentric overload; flywheel exercise; isoinertial devices; resistance training.