Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment
| Autor: | Jing Zhang, Linda S.H. Gan, Bradley C. Nindl, Priscilla Weiping Fan, Jason Kai Wei Lee, Karl E. Friedl, Heinrich W. Nolte |
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| Rok vydání: | 2022 |
| Předmět: |
Adult
Male Energy balance Physical Therapy Sports Therapy and Rehabilitation Young Adult Grip strength Animal science Humans Medicine Orthopedics and Sports Medicine Prospective Studies Energy deficit Prospective cohort study Hand Strength business.industry Physical Functional Performance Anthropometry Military Personnel Body Composition Metabolome Lean body mass Composition (visual arts) Energy Intake Energy Metabolism business Metabolic profile |
| Zdroj: | Journal of Science and Medicine in Sport. 25:89-94 |
| ISSN: | 1440-2440 |
| DOI: | 10.1016/j.jsams.2021.08.005 |
| Popis: | Objectives To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. Design Prospective cohort design. Methods Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase. Results Seventeen male participants (age: 24.5 ± 3.2 years, height: 173.9 ± 5.1 cm, body mass: 69.3 ± 3.2 kg, BMI: 22.9 ± 0.9 kg/m2, percent body fat: 14 ± 5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course. Conclusions Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts. |
| Databáze: | OpenAIRE |
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