Influence of armored vest sizing on markers of sprint performance

Abstract

Load carriage up to 150 lbs in the form of an armored vest and backpack is common for active duty military personnel. While the effects of load carriage on the performance of military-specific tasks has been well studied, no investigation has been made of the effects of armored vest sizing on task performance. The purpose of this study was to assess the effects of wearing oversized armored vests on sprint time and vest movement variables associated with sprinting 15 meters from standing and prone starting positions. Twenty two subjects (11 men and 11 women) performed the sprints wearing their best-sized vest (BS), a vest one size too large (OS1), and a vest two sizes too large (OS2). Subjects performed four sprints for each of the three vest conditions (BS, OS1, OS2), two from a standing position and two from a prone position, for a total of 12 maximal sprints. Split and total sprint times were collected and recorded using a timing pad and two timing gates. Vest movement was collected and recorded at 32 Hz and summarized in 1-second intervals as counts/second with two uniaxial accelerometry-based activity monitors mounted to the anterior side of the vests for testing. Collected variables were analyzed using multivariate two-factor repeated measures ANOVAs and Tukey's post-hoc test, all performed at the 0.05 alpha level. No differences were found for vest movement variables by condition (P>0.05). Vest movement was greater (P<0.01) when starting in a standing position than a prone position. When analyzed by gender, no significant main effects of vest condition on sprint time were found for men (P>0.05), but women were slower (P<0.01) when wearing the OS2 vest than the either the BS or OS1 vest. For all subjects, sprint time was slower (P<0.01) when starting in a prone position than a standing position. In conclusion, oversized armored vests impaired sprint performance in women. Further research is required to clarify whether gender or body size is more important in determining potential detriments to sprint performance when wearing oversized armor.