Robert P. Mello

Physiological responses to prolonged treadmill walking with external loads

SummaryLimited information is available regarding the physiological responses to prolonged load carriage. This study determined the energy cost of prolonged treadmill walking (fixed distance of 12 km) at speeds of 1.10 m·s−1, 1.35 m·s−1, and 1.60 m·s−1, unloaded (clothing mass 5.2 kg) and with external loads of 31.5 and 49.4 kg. Fifteen male subjects performed nine trials in random order over a 6-week period. Oxygen uptake (VO2) was determined at the end of the first 10 min and every 20 min thereafter. A 10-min rest period was allowed following each 50 min of walking. No changes occurred in VO2 over time in the unloaded condition at any speed. The 31.5 and 49.4 kg loads, however, produced significant increases (ranging from 10 to 18%) at the two fastest and at all three speeds, respectively, even at initial exercise intensities less than 30% VO2max. In addition, the 49.4 kg load elicited a significantly higher (P<0.05) VO2 than did the 31.5 kg load at all speeds. The measured values of metabolic cost were also compared to those predicted using the formula of Pandolf et al. In trials where VO2 increased significantly over time, predicted values underestimated the actual metabolic cost during the final minute by 10–16%. It is concluded that energy cost during prolonged load carriage is not constant but increases significantly over time even at low relative exercise intensities. It is further concluded that applying the prediction model which estimates energy expenditure from short-term load carriage efforts to prolonged load carriage can result in significant underestimations of the actual energy cost.

Comparison of the physical fitness of men and women entering the U.S. Army: 1978-1998.

PURPOSE To compare the physical fitness levels of recruits entering the U.S. Army in 1998 to those entering in 1978 and 1983. METHODS In 1998, 182 men and 168 women were tested before beginning basic training at Fort Jackson, SC. The measurements were 1) skin-fold estimation of percent body fat (%BF); 2) maximum oxygen uptake by treadmill running (VO2max); and 3) upper-body (UB), lower-body (LB), and upright pulling (UP) isometric strength. These data were compared to data from basic trainees at Fort Jackson in 1978 (skin folds, VO2max, UB, and LB) and 1983 (skin folds and UP). RESULTS Body weight (BW) of 1998 recruits was greater (P < 0.05) than 1978 recruits (men, 12%; women, 6%) and 1983 recruits (men, 8%; women, 7%). %BF of 1998 recruits was greater (P < 0.05) than 1978 recruits (men, 15%; women, 5%) and 1983 recruits (men, 15%; women, 17%). The 1998 men had more fat-free mass (FFM) (P < 0.05) than men in 1978 (8%) or 1983 (5%), whereas 1998 women were only different from those measured in 1978 (4%, P < 0.05). The VO2max of men (50.6 +/- 6.2 mL x kg(-1) x min(-1)) was equivalent to men in 1978, whereas that of women (39.7 +/- 5.2 mL x kg(-1) x min(-1)) was 6% greater (P < 0.05). The 1998 recruits were stronger (P < 0.05) on all measures of muscle strength than recruits measured in 1978 (men, UB = 16%, LB = 12%; women, UB = 18%, LB = 6%) and 1983 (men, UP = 7%; women, UP = 6%). CONCLUSION The aerobic capacity, muscle strength, and FFM of 1998 recruits is comparable to or greater than that of 1978 and 1983 recruits; however, 1998 recruits tended to have more BW and a greater %BF.

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.

Evaluation of a maximal predictive cycle ergometer test of aerobic power

SummaryA maximal predictive cycle ergometer (CE) test for estimating maximal oxygen uptake (

Maximum Acceptable Load for Lifting and Carrying in Two-Person Teams

\dot V

The Effect of Lift Height on Maximal Lifting Capabilities of Men and Women

O2 max) was evaluated in 15 male and 12 female subjects. The test consisted of pedalling a cycle ergometer (Monark) at 75 rev·min−1, beginning at an intensity of 37.5 watts and increasing by this amount each min until the subject could no longer maintain pedal rate. The highest work rate achieved was recorded as the endpoint of the test and used to construct regression equations to predict