It is unknown to what extent age and race may modify the protective effect of high fitness on injury and attrition. The data used by the committee to analyze the combined effect of fitness and BMI on injury and attrition does not contain sufficient numbers to permit further stratification by categories of race and age. Research is needed to address this topic. Whenever possible, associations should be disaggregated by race to assess the extent to which associations are constant within strata of race.
Smoking A history of smoking prior to the start of basic training is a risk factor for injury; this is addressed in Chapter 7. There are a number of plausible biological mechanisms through which smoking may predispose a recruit to injury from the stresses imposed on the body in basic training, including restricted circulatory flow and degraded ability to maintain high-quality bone health. In addition, smoking may be correlated with behavioral factors that are independent risk factors for injury, such as risk-taking behavior.
Previous Injury History A positive injury history is a risk factor for injury during basic training (Table 4-10), and similar findings are reported in the sports medicine literature for athletic populations (Kucera et al., 2005). The mechanism by which a positive history of previous injury is associated with the incidence of injury is currently not well understood. Like smoking, this may reflect a positive correlation with behavioral factors (such as risk-taking) that are predictive of injury. It may also reflect an anatomical weakness in a particular site in the body, such as chronic ankle instability, increased risk due to low physical fitness and fatigue, or poor rehabilitation of an original injury that may predispose that body site to reinjury.
The logic behind assessments of functional capacities is that a person’s physical abilities (capacity) can be measured, documented, and evaluated via a standard physical testing procedure and compared with physical exposures that are required to perform a particular task or job. Thus, by matching worker capabilities to task demands in this manner, it is thought that the probability that an individual’s capacity is exceeded by the job requirements can be minimized. Furthermore, it is assumed that if task demands are sustained within the limits of the job demands, the risk of a task-related injury is minimized. These assessments have been successfully employed in numerous industrial situations in an attempt to control the cost of musculoskeletal injuries in the workforce (Key, 1999).