Background: Each branch of the U.S. armed forces has standards for physical
fitness as well as programs for ensuring compliance with these standards.
In the U.S. Air Force (USAF), physical fitness is assessed using submaximal
cycle ergometry to estimate maximal oxygen uptake (VO2max). The purpose of
this study was to identify the independent effects of demographic and beha
vioral factors on risk of failure to meet USAF fitness standards (hereafter
called low fitness).
Methods: A retrospective cohort study (N=38,837) was conducted using self-r
eported health risk assessment data and cycle ergometry data from active-du
ty Air Force (ADAF) members. Poisson regression techniques were used to est
imate the associations between the factors studied and low fitness.
Results: The factors studied had different effects depending on whether mem
bers passed or failed fitness testing in the previous year. All predictors
had weaker effects among those with previous failure. Among those with a pr
evious pass, demographic groups at increased risk were toward the upper end
of the ADAF age distribution, senior enlisted men, and blacks. Overweight/
obesity was the behavioral factor with the largest effect among men, with a
erobic exercise frequency ranked second; among women, the order of these tw
o factors was reversed. Cigarette smoking only had an adverse effect among
men. For a hypothetical ADAF man who was sedentary, obese, and smoked, the
results suggested that aggressive behavioral risk factor modification would
produce a 77% relative decrease in risk of low fitness.
Conclusions: Among ADAF members, both demographic and behavioral factors pl
ay important roles in physical fitness. Behavioral risk factors are prevale
nt and potentially modifiable. These data suggest that, depending on a memb
er's risk factor profile, behavioral risk factor modification may produce i
mpressive reductions in risk of low fitness among ADAF personnel.