The Influence of Single-Leg Isometrics on Ground Interactions during a Baseball Swing
Date of Award
Winter 1-24-2025
Document Type
Dissertation
Degree Name
Doctor of Kinesiology (EdD)
Department
Kinesiology
Abstract
Sports science plays a vital role in modern athletics, with metrics like GRF serving as key performance indicators, particularly in baseball. This study investigated the effects of a single-leg fast-ramping isometric exercise targeting hamstring activation on vGRF at the lead leg during a baseball swing. Ten male participants (mean age 15.7 years, SD = 1.42) participated in a randomized within-subject experimental design. GRF was measured at toe touch, heel plant, and contact using a pressure plate (Sensors Edge) and synchronized video. The intervention involved a 90/90 hip lift to stabilize the lumbopelvic complex, aiming to enhance GRF. Pre- and post-intervention swings were compared using repeated measures ANOVA (α = 0.05). Results revealed significant changes in GRF over time (p = .005) and at toe touch (p < .001). Lead leg pressure decreased at toe touch (p < .01, ES = 0.17) and increased at heel plant (p < .01, ES = 0.11) but showed no significant change at contact (p = .27, ES = 0.04). These findings suggest the intervention influenced lead leg pressure at specific phases, with minor practical significance. Future research should explore different batting conditions, interventions, and acute variables to further understand GRF's role in baseball swings.