Occupational relevance and body mass bias in military physical fitness tests.

Recent evidence makes a compelling case that US Army, Navy, and Air Force health-related physical fitness tests penalize larger, not just fatter, service members. As a result, they tend to receive lower scores than their lighter counterparts, the magnitude of which can be explained by biologic scaling laws. Larger personnel, on the other hand, tend to be better performers of work-related fitness tasks such as load carriage, heavy lifting, and materiel handling. This has been explained by empirical evidence that lean body mass and lean body mass to dead mass ratio (dead mass = fat mass and external load to be carried/lifted) are more potent determinants of performance of these military tasks than the fitness test events such as push-ups, sit-ups, or 2-mile-distance run time. Because promotions are based, in part, on fitness test performance, lighter personnel have an advancement advantage, although they tend to be poorer performers on many tests of work-related fitness. Several strategies have been proposed to rectify this incongruence including balanced tests, scaled scores, and correction factors--yet most need large-scale validation. Because nearly all subjects in such research have been men, future investigations should focus on women and elucidate the feasibility of universal physical fitness tests for all that include measures of health- and work-related fitness while imposing no systematic body mass bias.