Is High-Intensity Functional Training (HIFT)/CrossFit Safe for Military Fitness Training?

Abstract

High-intensity functional training (HIFT) is a promising fitness paradigm that gained popularity among military populations. Rather than biasing workouts toward maximizing fitness domains such as aerobic endurance, HIFT workouts are designed to promote general physical preparedness. HIFT programs have proliferated as a result of concerns about the relevance of traditional physical training (PT), which historically focused on aerobic condition via running. Other concerns about traditional PT include: (1) the relevance of service fitness tests given current combat demands, (2) the perception that military PT is geared toward passing service fitness tests, and (3) that training for combat requires more than just aerobic endurance. Despite its' popularity in the military, concerns have been raised about HIFT's injury potential, leading to some approaches being labeled as "extreme conditioning programs" by several military and civilian experts. Given HIFT programs' popularity in the military and concerns about injury, a review of data on HIFT injury potential is needed to inform military policy. The purpose of this review is to: (1) provide an overview of scientific methods used to appropriately compare injury rates among fitness activities and (2) evaluate scientific data regarding HIFT injury risk compared to traditional military PT and other accepted fitness activities.

Figure 1

Computational Formulas for Injury Indices.

Figure 2

Injury Incidence Proportions for Army Trainees*. *Figure adapted from data provided in the Department of the Army report and Knapik and colleagues.

Figure 3

Injury Incidence Proportions Among Army Personnel Before and After Implementation of ATAC/CrossFit/RAW as compared to Army Physical Readiness Training (APRT)*. *Figure adapted from data provided by Grier and colleagues.