respiratory fitness with these different field tests because the mile run was not included in test batteries until the 1980s (Corbin and Pangrazi, 1992).
Other sources of data to assess secular trends in cardiorespiratory fitness are the Health Examination Survey Cycle III (1966-1970) and the most recent NHANES (1999-2002). The Health Examination Survey included a treadmill exercise test for 12- to 17-year-olds (McDowell, 1989; Gillum, 1989) and NHANES (1999-2002) administered a treadmill exercise test to persons ages 12 to 49. Both protocols had two incremental work stages ranging from 2-3 minutes. The protocols were not identical; therefore, the comparison should be interpreted with caution. For youth ages 12 to 17, the mean VO2max for boys decreased approximately 10 percent during the 35-year period, whereas there was no difference in mean VO2max for girls.
Sharp and colleagues (2002) compared the cardiorespiratory fitness levels of men and women entering the Army over a 20-year period (1978-1998). VO2max was measured using open-circuit indirect calorimetry during a treadmill running protocol. The mean VO2max of men in the 1978 sample was equivalent to the 1998 sample (50.7 ± 4.8 ml/kg/min in 1978 and 50.6 ± 6.2 ml/kg/min in 1998). Among women, the mean VO2max in the 1998 sample was 6 percent higher than the 1978 sample (36.9 ± 3.8 ml/ kg/min in 1978 and 39.2 ± 5.1 ml/kg/min in 1998). Thus, the recruits in 1998 had cardiorespiratory fitness levels that were equal to or greater than recruits in 1978.
This section focuses on the relationship of physical fitness to injury and attrition in basic training. Data are presented demonstrating that low physical fitness is closely associated with diminished performance in basic training (as measured by injury and attrition status).
Even before they are shipped to basic training, some potential recruits arrive at the military entrance processing station (MEPS) with chronic injuries and other musculoskeletal conditions. Some of these conditions preclude military service, while others, following review through the waiver system, are deemed to be admissible. It is also highly probable that there is a group of recruits with musculoskeletal conditions that go undetected at the MEPS.