David J. Gutekunst

Effects of two different eight - week training programs on military physical performance

Various physical demands are placed on soldiers, whose effectiveness and survivability depend on their combat-specific physical fitness. Because sport training programs involving weight-based training have proven effective, this study examined the value of such a program for short-term military training using combat-relevant tests. A male weight-based training (WBT) group (n = 15; mean ± SD: 27.0 ± 4.7 years, 173.8 ± 5.8 cm, 80.9 ± 12.7 kg) performed full-body weight-based training workouts, 3.2-km runs, interval training, agility training, and progressively loaded 8-km backpack hikes. A male Army Standardized Physical Training (SPT) group (n = 17; mean ± SD: 29.0 ± 4.6 years, 179.7 ± 8.2 cm, 84.5 ± 10.4 kg) followed the new Army Standardized Physical Training program of stretching, varied calisthenics, movement drills, sprint intervals, shuttle running, and distance runs. Both groups exercised for 1.5 hours a day, 5 days a week for 8 weeks. The following training-induced changes were statistically significant (P < 0.05) for both training groups: 3.2-km run or walk with 32-kg load (minutes), 24.5 ± 3.2 to 21.0 ± 2.8 (SPT) and 24.9 ± 2.8 to 21.1 ± 2.2 (WBT); 400-m run with 18-kg load (seconds), 94.5 ± 14.2 to 84.4 ± 11.9 (SPT) and 100.1 ± 16.1 to 84.0 ± 8.4 (WBT); obstacle course with 18-kg load (seconds), 73.3 ± 10.1 to 61.6 ± 7.7 (SPT) and 66.8 ± 10.0 to 60.1 ± 8.7 (WBT); 5 30-m sprints to prone (seconds), 63.5 ± 4.8 to 59.8 ± 4.1 (SPT) and 60.4 ± 4.2 to 58.9 ± 2.7 (WBT); and 80-kg casualty rescue from 50 m (seconds), 65.8 ± 40.0 to 42.1 ± 9.9 (SPT) and 57.6 ± 22.0 to 44.2 ± 8.8 (WBT). Of these tests, only the obstacle course showed significant difference in improvement between the two training groups. Thus, for short-term (i.e., 8-week) training of relatively untrained men, the Armys new Standardized Physical Training program and a weight-based training experimental program can produce similar, significant, and meaningful improvements in military physical performance. Further research would be needed to determine whether weight-based training provides an advantage over a longer training period.

Prediction of Simulated Battlefield Physical Performance from Field-Expedient Tests

Predictive models of battlefield physical performance can benefit the military. To develop models, 32 physically trained men (mean +/- SD: 28.0 +/- 4.7 years, 82.1 +/- 11.3 kg, 176.3 +/- 7.5 cm) underwent (1) anthropometric measures: height and body mass; (2) fitness tests: push-ups, sit-ups, 3.2-km run, vertical jump, horizontal jump; (3) simulated battlefield physical performance in fighting load: five 30-m sprints prone to prone, 400-m run, obstacle course, and casualty recovery. Although greater body mass was positively associated with better casualty recovery performance, it showed trends toward poorer performance on all the other fitness and military performance tests. Regression equations well predicted the simulated battlefield performance from the anthropometric measures and physical fitness tests (r = 0.77-0.82). The vertical jump entered all four prediction equations and the horizontal jump entered one of them. The equations, using input from easy to administer tests, effectively predict simulated battlefield physical performance.

Lower Extremity Mechanics During Marching at Three Different Cadences for 60 Minutes

During group marches, soldiers must walk in step with one another at the same imposed cadence. The literature suggests that shorter trainees may be more susceptible to injury due to overstriding that can occur when taller recruits dictate marching cadence. This study assessed the effects of fixed cadence simulated marching at cadences above and below preferred step rate (PSR) on lower extremity joint mechanics in individuals who were unaccustomed to marching. During three separate visits, 13 volunteers walked with a 20 kg load on a force-sensing treadmill at self-selected PSR, PSR+15% (shorter strides), and PSR-15% (longer strides) at 1.3 m/s for 60 min. Two-way RM ANOVAs (cadence by time) were performed during the stance phase. Ranges of motion and anteroposterior ground reaction force increased significantly as cadence decreased (P < .03). Knee extension moment increased slightly when step rate decreased from PSR+15% (shortest strides, 0.85 ± 0.2 N m/kg) to PSR (0.87 ± 0.3 N m/kg, 3% increase); however, this increase was substantially greater (20% increase) when cadence was decreased from PSR to PSR-15% (longest strides, 1.09 ± 0.3 N m/kg). Our results indicate that overstriding during fixed-cadence marching is a factor that can substantially increase mechanical stress on lower extremity joints.