Occupation and other risk factors for injury among enlisted U.S. Army Soldiers.

OBJECTIVE: To investigate injury risk associated with occupation and occupational physical demand levels among U.S. Army Soldiers. STUDY DESIGN: Retrospective cohort study. METHODS: Personal characteristics, physical fitness, military occupational specialty (MOS), and injury data were obtained by survey from Soldiers in an Army light infantry brigade (n = 2101). Odds ratios (OR) and 95% confidence intervals (95% CI) from a multivariate analysis assessing injury risk were calculated. RESULTS: Injury incidence for the prior 12 months was 43%. Physical fitness and behavioral factors associated with injury risk included age 21-29 (OR [age 21-29/age ≤ 20] = 1.37, 95% CI 1.00-1.90), BMI 27.5-29.9 (high-overweight) (OR high-overweight/normal = 1.62, 95% CI 1.20-2.18); BMI >29.9 (obese) (OR obese/normal = 1.73, 95% CI 1.23-2.44), cigarette smoking (OR Smoker/Nonsmoker = 1.34, 95% CI 1.11-1.63), and poor APFT two mile run performance (OR (Q4/Q1) = 1.61, 95% CI 1.19-2.19). Higher risk of injury was associated with some MOSs (OR (Chemical, Explosives & Ammunition/Infantry) = 2.82, 95% CI 1.19-6.68; OR (Armor/Infantry) = 1.53, 95% CI 1.13-2.07). CONCLUSION: This study identified a number of potentially modifiable risk factors for injuries including: maintenance of healthy weight, improved aerobic endurance, and reduction in smoking. Results also indicate certain Army occupations may be at higher risk of injury. Further investigation into reasons for their higher risk is warranted.

Dose-response relationship between interval training frequency and magnitude of improvement in lactate threshold.

The purpose of this study was to determine if interval training at 110-120% of peak power output one and two days/wk in addition to habitual training would elicit improvements in lactate threshold (LT) in a dose response manner. Twenty physically active individuals completed this study: age--21.1+/-1.3 yr, height--172.1+/-7.4 cm, body mass--68.4+/-9.1 kg, VO (2)max--45.3+/-5.2 mL/kg/min; and were randomly assigned into two separate 6 wk training groups--either 1 day/wk interval training or 2 days/wk interval training at 110-120% of peak workload (from an incremental exercise test) on a cycle ergometer. After 6 wk, LT (% VO (2)max) increased significantly ( P<0.05) in both 1 day/wk (4.3+/-3.2%) and 2 days/wk (8.2+/-2.6%) groups. A two-factor mixed ANOVA identified a significant interaction between exercise frequency and LT (%VO (2)max) values ( P<0.05) indicating that LT responded differently to 1 day/wk and 2 days/wk of interval training. Findings from the present study show high-intensity, interval training to be a successful strategy for modifying this important metabolic threshold. Moreover, results suggest that there is a dose-response relationship between frequency of interval training and the magnitude of LT improvement.