Sarah B. Jones

Temporal Changes in the Physical Fitness of US Army Recruits

This article defines physical fitness and then reviews the literature on temporal trends in the physical fitness of new US Army recruits. Nineteen papers were found that met the review criteria and had published recruit fitness data from 1975 to 2003. The limited data on recruit muscle strength suggested an increase from 1978 to 1998 (20-year period). Data on push-ups and sit-ups suggested no change in muscular endurance between 1984 and 2003 (19-year period). Limited data suggested that maximal oxygen uptake (V̇O2max) [mL/kg/min] of male recruits did not change from 1975 to 1998 (23-year period), while there was some indication of a small increase in female recruit V̇O2max in the same period. On the other hand, slower times on 1-mile (1.6km) and 2-mile (3.2km) runs indicate declines in aerobic performance from 1987 to 2003 (16-year period). The apparent discrepancy between the V̇O2max and endurance running data may indicate that recruits are not as proficient at applying their aerobic capability to performance tasks, such as timed runs, possibly because of factors such as increased bodyweight, reduced experience with running, lower motivation and/or environmental factors. Recruit height, weight and body mass index have progressively increased between 1978 and 2003 (25-year period). Both the body fat and fat-free mass of male recruits increased from 1978 to 1998 (20-year period); however, body composition data on female recruits did not show a consistent trend. In this same time period, the literature contained little data on youth physical activity but there was some suggestion that caloric consumption increased. This article indicates that temporal trends in recruit fitness differ depending on the fitness component measured. The very limited comparable data on civilian populations showed trends similar to the recruit data.

Injury Rates and Injury Risk Factors among U.S. Army Wheel Vehicle Mechanics

This study describes injury rates, injury diagnoses, anatomical locations of injuries, limited duty days, and activities associated with injuries in a sample of Army mechanics. Medical records of 518 male and 43 female Army mechanics were screened for injuries during 1 year at a large U.S. Army installation. Weight, height, age, and ethnicity were also extracted from the medical records. Body mass index was calculated as weight/height2. Overall injury rates for men and women were 124 and 156 injuries/100 person-years, respectively, with a rate of 127 injuries/100 person-years for all soldiers combined. Women had higher overuse injury rates while men had higher traumatic injury rates. Limited duty days for men and women were 2,076 and 1,966 days/100 person-years, respectively. The lower back, knee, ankle, foot, and shoulder involved 61% of the injuries. Activities associated with injury included (in order of incidence) physical training, mechanical work, sports, airborne-related activities, road marching, garrison/home activities, and chronic conditions. Among the men, elevated injury risk was associated with higher body weight and higher body mass index. It may be possible to prevent many injuries by implementation of evidenced-based interventions currently available in the literature.

The Validity of Self-Reported Physical Fitness Test Scores

Epidemiological studies often have to rely on a participants self-reporting of information. The validity of the self-report instrument is an important consideration in any study. The purpose of this investigation was to determine the validity of self-reported Army Physical Fitness Test (APFT) scores. The APFT is administered to all soldiers in the U.S. Army twice a year and consists of the maximum number of push-ups completed in 2 minutes, the maximum number of sit-ups completed in 2 minutes, and a 2-mile run for time. Army mechanics responded to a questionnaire in March and June 2004 asking them to report the exact scores of each event on their most recent APFT. Actual APFT scores were obtained from the soldiers military unit. The mean +/- standard deviation (SD) of actual and self-reported numbers of push-ups was 61 +/- 14 and 65 +/- 13, respectively. The mean +/- SD of actual and self-reported numbers of sit-ups were 66 +/- 10 and 68 +/- 10, respectively. The mean +/- SD of actual and self-reported run times (minutes) were 14.8 +/- 1.4 and 14.6 +/- 1.4, respectively. Correlations between actual and self-reported push-ups, sit-ups, and run were 0.83, 0.71, and 0.85, respectively. On average, soldiers tended to slightly over-report performance on all APFT events and individual self-reported scores could vary widely from actual scores based on Bland-Altman plots. Despite this, the close correlations between the actual and self-reported scores suggest that self-reported values are adequate for most epidemiological military studies involving larger sample sizes.