Volleyball requires explosive strength to achieve high levels of performance. Strength coaches commonly use plyometric exercises such as box jumps and depth jumps to enhance vertical jump performance; however, fatigue may impair training performance. Purpose: The purpose of this study was to assess fatigue, via force production, during ten box jumps and ten depth jumps. Methods: Ten Division I female collegiate volleyball players participated in this study (age, 19.1 ± 1.28 yrs, height, 177.33 ± 8.13 cm, body mass, 73.92 ± 5.30 kg). Participants attended two test sessions separated by a 72 hour rest period. Subjects started visit one by completing a five minute warm-up at a self-selected cadence on a cycle ergometer. Following the warm up, subjects randomly performed either ten box jumps or ten depth jumps with five seconds rest between repetitions. Investigators set relative box height for each subject as the distance from mid thigh to the floor. Subject used the Vertec device as a motivation for maximal performance. On visit two, subjects performed the other condition. Peak ground reaction force (GRF) was used to determine fatigue across all ten jumps for each condition. Results: ANOVA demonstrated no significant difference in GRF across all repetitions for either condition (box jump 1: 1248.18N ± 206.61N, box jump 10: 1277.59N ± 287.42N; depth jump 1: 1595.36N ± 363.96N, depth jump 10: 1681.12N ± 336.46N). Conclusion: Post Activation Potentiation and training adaptations are induced by high intensity activity. Performing these activities, without undue fatigue, is the basis for muscular adaptations. Practical Application: Since no evidence of fatigue appeared across ten repetitions (as measured by GRF), strength and conditioning coaches might employ this volume and intensity to elicit a training adaptation.
