(1) EFFECT OF AN ISOINERTIAL POST-ACTIVATION POTENTIATION PROTOCOL ON COUNTERMOVEMENT JUMP KINETICS

Background: Acute bouts of isoinertial training can enhance muscle force production during subsequent plyometric exercise. Evidence supports flywheel isoinertial half squats as an effective lower-body preload activity. However, further research is necessary to determine the degree to which such post-activation potentiation (PAP) conditioning activities influence jump kinetics.

Purpose: To compare countermovement jump (CMJ) performances following a traditional dynamic warmup (TDW) and flywheel (FW) warmup.

Methods: College-aged students (9 men; 4 women), with >2 years of resistance training experience, and the ability to complete a 1.25x body weight back-squat participated. The crossover design consisted of 3 sessions. Session 1 included anthropometric measurements, strength assessment, and familiarization with the FW half-squat. Sessions 2 and 3 consisted of the randomized testing condition (FW or TDW). Prior to FW and TDW conditions, participants completed 5 minutes (min) of treadmill walking (3.5 mph, 1.5% grade). In the TDW condition, participants completed 20 seconds of skipping, 20 bodyweight lunges, and 20 bodyweight squats, interspered by 1 min of passive recovery. In the FW condition, participants completed 3 sets of 10 repetitions of bilateral half squats, interspersed by 2 min of passive recovery. Load used for the FW protocol was 1 large disk (mass = 4 kg; inertia = 0.050 kg·m²) and 1 medium disk (mass = 2.8 kg; inertia = 0.025 kg·m²). Upon completion of FW or TDW, participants completed a maximal CMJ at 1 min, 3 min, 5 min, 7 min, and 9 min post-intervention. Analyzed variables included CMJ height (cm), reactive strength index modified (m/s), braking force (N), and power relative to body mass (W/kg). Statistical analyses included 2 (condition; TDW or FW) x 5 (CMJ time point) repeated measures analysis of variance (RMANOVA). Significance was set a priori to p< 0.05. Bonferroni post hoc analysis was used to identify differences between conditions.

Results: Figure 1 includes performance outcomes for CMJ height. RSImod, braking force, and power relative to body mass did not differ between conditions. CMJ height had a significant condition x time interaction effect (p=0.039). Post-hoc analyses indicated that CMJ height was greater following the FW warm-up at 5 min (p=0.02), 7 min (p=0.04), and 9 min (p=0.03). There were significant time-effect differences in CMJ height across trails for the FW condition, but not for the TDW condition. Post-hoc analyses indicated that CMJ height at 3 min (p=0.02), 5 min (p=0.01), 7 min (p=0.02), and 9 min (p=0.01) were greater than at 1 min. Figure 1 includes performance outcomes for CMJ height.

Conclusions: The utilization of a FW half squat protocol may enhance CMJ height. Practical Applications: FW half squats can be used to improve lower-body explosiveness during the CMJ; therefore, it is recommended to incorporate them as a PAP preload activity, prior to performing lower-body plyometric exercise.

Acknowledgements: None