Relationship Of Sex And Physical Activity On Vertical Jump Power Changes In U.s. Army Trainees

Abstract

One goal of Basic Combat Training (BCT) is to improve the general fitness of recruits to successfully meet the demands of military activities. Previous studies have focused on the aerobic fitness responses to BCT. In contrast few investigations have examined the changes in whole body power production following BCT and if these changes may be modified by various pre-BCT factors. More specifically, do all recruits show similar training responses in terms of muscular power production as measured by vertical jump (VJ) testing? PURPOSE: To determine the relationship of sex and physical activity history on changes in VJ power output following BCT. METHODS: Four hundred fourteen recruits (298 men; 116 women; (mean ± SD) age: 21 ± 3 y; height: 172 ± 9 cm; body mass: 73.0 ± 13.4 kg) performed maximal VJ testing before and after 8 weeks of U.S. Army BCT. Body mass and VJ height were used to estimate VJ peak power using the Harman equation. Recruits filled out a survey on their prior physical activity during the 2 months prior to entering BCT. Logistic regression was used to calculate odds ratios showing whether sex or physical activity prior to BCT is predictive of changes in a recruit’s VJ power output. RESULTS: Females were 2.1 times more likely to show an increase in VJ power than males (p=0.01). Recruits that performed running training 3-4 times per week were 1.8 times more likely to improve their VJ power than recruits that only ran 0-2 times per week (p=0.01). Recruits that had an average running mile time from 7:00-7:59 (min:sec) were 1.6 times more likely to generate more VJ power than those running at a sub 7:00 mile time (p=0.03). CONCLUSION: Recruits showed differential changes in VJ performance following BCT, depending on sex, prior running training experience, and average 1-mile running time. DISCLAIMER: The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government. Supported by the U.S. Army Medical Research and Materiel Command.