Author

DeRosia

Date of Award

8-2019

Degree Name

Master of Science

Department

Human Performance and Health Education

First Advisor

Dr. Sangwoo Lee

Second Advisor

Dr. Timothy Michael

Third Advisor

Dr. Nicholas Hanson

Keywords

Postactivation potentiation, kinematics, power clean, maximal isometric contraction, ground reaction force

Access Setting

Masters Thesis-Open Access

Abstract

The purpose of this study was to investigate the differences in vertical ground reaction force (VGRF) production and myoelectric activity after performing maximal isometric contractions at different hip joint angles. 10 healthy, experienced participants reported to the lab on two separate occasions where they performed 3 power cleans at baseline, then 4 maximal isometric deadlifts at either ~50° hip flexion angle (Max) or ~90° hip flexion angle (Min). Following the isometric deadlifts, another 3 power clean trials at 70% 1 repetition maximum were performed and used as a post-test. The isometric deadlifts served as the conditioning contraction (CC) to induce Postactivation Potentiation (PAP). Repeated measures analysis of variance revealed no significant changes VGRF from pre to post testing for either condition. No significant differences were observed in electromyography (EMG) for any muscle, regardless of time or condition. Maximal isometric contractions with minimal rest following may not be an optimal protocol for inducing PAP prior to power cleans. Furthermore, potentiation effects may not be observed during power cleans performed at 70% 1RM since only submaximal effort is required for successful execution of the exercise.

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