Recorded time in MVPA and energy expenditure varies substantially among physical activity monitors. Thus, when comparing physical activity level among studies, it is essential to know the type of physical activity monitor being used.

Previous studies show that body composition is related to injury risk and physical performance in soldiers. Thus, valid methods for measuring body composition in military personnel are needed. The frequently used body mass index method is not a valid measure of body composition in soldiers, but reliability and validity of alternative field methods are less investigated in military personnel. Thus, we carried out test and retest of skinfold (SKF), single frequency bioelectrical impedance analysis (SF-BIA), and multifrequency bioelectrical impedance analysis measurements in 65 male and female soldiers. Several validated equations were used to predict percent body fat from these methods. Dual-energy X-ray absorptiometry was also measured, and acted as the criterion method. Results showed that SF-BIA was the most reliable method in both genders. In women, SF-BIA was also the most valid method, whereas SKF or a combination of SKF and SF-BIA produced the highest validity in men. Reliability and validity varied substantially among the equations examined. The best methods and equations produced test-retest 95% limits of agreement below ±1% points, whereas the corresponding validity figures were ±3.5% points. Each investigator and practitioner must consider whether such measurement errors are acceptable for its specific use.

Purpose To investigate sex differences in the effect of a military field exercise on physical performance, body composition, and blood biomarkers. Methods Measurements were done in 23 male and 12 female conscripts before, and 0, 1, 3, 7, and 14 days after a 6‐day military field exercise. Results During the field exercise, body mass decreased more in men (−6.5 ± 1.1 kg) than in women (−2.7 ± 0.7 kg), and muscle mass decreased only in men (−2.7 ± 1.0 kg). Body composition recovered within one week. Performance decreased, with no differences between men and women for countermovement jump (CMJ,‐19 ± 8 vs. −18 ± 11%), medicine ball throw (MBT, −11 ± 7 vs. −11 ± 7%), and an anaerobic performance test (EVAC, −55 ± 22 vs. −47 ± 31%, men and women, respectively). MBT and EVAC performance recovered within two weeks, whereas CMJ performance was still reduced in men (−17 ± 6%) and women (−9 ± 8%) after two weeks recovery, with a larger reduction in men. Both men and women decreased [IGF‐1] (−28 ± 9 vs. −41 ± 8%) and increased [cortisol] (26 ± 26 vs. 66 ± 93%, men and women, respectively) during the exercise. Most biomarkers returned to baseline values within one week. Conclusions Men lost more body mass and muscle mass than women during a field exercise, but these differences did not lead to sex differences in changes in explosive strength and anaerobic performance. However, women recovered explosive strength in the legs faster than men.

is regularly monitored in military personnel, as occupational demands require a certain level of fitness. Distance run (eg, 2 mile) is typically carried out to measure aerobic fitness, but an alternative test could be the 20 meter shuttle run test (20 m SRT). The present study aimed to evaluate validity and reliability of this test in military personnel. An equation for predicting maximal oxygen uptake (VO2max) was developed on 38 Home Guard soldiers and cross validated in 28 Air Force cadets. Reliability of the 20 m SRT, expressed as mean difference in estimated VO2max-- 95% limits of agreement, was -0.8 +/- 3.1 mL x kg(-1) min(-1). Mean difference +/- limits of agreement between estimated and measured VO2max was -0.4 +/- 6.2 mL.kg(-1)x min-'. The 20 m SRT seems to be a reliable test, although validity is less certain, as relatively high variability was observed between measured and estimated VO2max from the 20 m SRT.