Effects of winter military training on energy balance, whole-body protein balance, muscle damage, soreness, and physical performance

Margolis, Lee M.; Murphy, Nancy; Martini, Svein; Spitz, Marissa G; Thrane, Ingjerd; McGraw, Susan M.; Blatny, Janet-Martha; Castellani, John W.; Rood, Jennifer; Young, Andrew; Montain, Scott J.; Gundersen, Yngvar; Pasiakos, Stefan M.

doi:10.1139/apnm-2014-0212

Cited by 91 publications

(153 citation statements)

References 27 publications

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“…; Margolis et al. , ). As energy intakes were estimated based on rations provided to the soldiers they must be considered rough estimates as meals may have been omitted and in between meal snacks may have been added.…”

Section: Discussionmentioning

confidence: 97%

Increased autophagy signaling but not proteasome activity in human skeletal muscle after prolonged low‐intensity exercise with negative energy balance

et al. 2017

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Little is known about the molecular regulation of skeletal muscle protein turnover during exercise in field conditions where energy is intake inadequate. Here, 17 male and 7 female soldiers performed an 8 days long field‐based military operation. Vastus lateralis muscle biopsies, in which autophagy, the ubiquitin–proteasome system, and the mTORC1 signaling pathway were studied, were collected before and after the operation. The 187 h long operation resulted in a 15% and 29% negative energy balance as well as a 4.1% and 4.6% loss of body mass in women and men, respectively. After the operation protein levels of ULK1 as well as the phosphorylation of ULK1Ser317 and ULK1Ser555 had increased by 11%, 39%, and 13%, respectively, and this was supported by a 17% increased phosphorylation of AMPKThr172 (P < 0.05). The LC3b‐I/II ratio was threefold higher after compared to before the operation (P < 0.05), whereas protein levels of p62/SQSTM1 were unchanged. The β1, β2, and β5 activity of the proteasome and protein levels of MAFbx did not change, whereas levels of MuRF‐1 were slightly reduced (6%, P < 0.05). Protein levels and phosphorylation status of key components in the mTORC1 signaling pathway remained at basal levels after the operation. Muscle levels of glycogen decreased from 269 ± 12 to 181 ± 9 mmol·kg dry·muscle−1 after the exercise period (P < 0.05). In conclusion, the 8 days of field‐based exercise resulted in induction of autophagy without any increase in proteasome activity or protein ubiquitination. Simultaneously, the regulation of protein synthesis through the mTORC1 signaling pathway was maintained.

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Section: Discussionmentioning

confidence: 97%

Increased autophagy signaling but not proteasome activity in human skeletal muscle after prolonged low‐intensity exercise with negative energy balance

et al. 2017

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“…Soldiers participating in military field exercises or warfare often operate in a state of energy deficit in a demanding environment, with little opportunity for rest, recovery, and nutritional intake . The energy imbalance typically leads to a catabolic physiological state, accompanied by alterations in body composition, including loss of overall body mass, lean body mass (LBM), and fat mass .…”

Section: Introductionmentioning

confidence: 98%

No effect of increasing protein intake during military exercise with severe energy deficit on body composition and performance

Øfsteng

Garthe

Jøsok

et al. 2020

Scandinavian Med Sci Sports

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In this study, we compare the effects of isocaloric high‐ (HIGH: 2 g kg−1 d−1, n = 19) and low‐protein diet (LOW: 1 g kg−1 d−1, n = 19) on changes in body composition, muscle strength, and endocrine variables in response to a 10‐day military field exercise with energy deficit, followed by 7 days of recovery. Body composition (DXA), one repetition maximum (1RM) bench and leg press, counter‐movement jump height (CMJ) and blood variables were assessed before and after the exercise. Performance and blood variables were reassessed after 7 days of recovery. The 10‐day exercise resulted in severe energy deficit in both LOW and HIGH (−4373 ± 1250, −4271 ± 1075 kcal d−1) and led to decreased body mass (−6.1%, −5.2%), fat mass (−40.5%, −33.4%), 1RM bench press (−9.5%, −9.7%), 1RM leg press (−7.8%, −8.3%), and CMJ (−14.7%, −14.6%), with no differences between groups. No change was seen for fat‐free mass. In both groups, the exercise led to a switch toward a catabolic physiological milieu, evident as reduced levels of anabolic hormones (testosterone, IGF‐1) and increased levels of cortisol (more pronounced in HIGH, P < .05). Both groups also displayed substantial increases in creatine kinase. After 7 days of recovery, most variables had returned to close‐to pre‐exercise levels, except for CMJ, which remained at reduced levels. In conclusion, increased protein intake during 10‐day military field exercise with severe energy deficiency did not mitigate loss of body mass or impairment of physical performance.

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“…; Margolis et al. ), external load from equipment carried, (Patton et al. ; Knapik and Reynolds ) and climatic circumstances (Sawka et al.…”

Section: Introductionmentioning

confidence: 99%

“…) and winter training (Margolis et al. ). Hartmann and Mester () stated that increased CK activity together with decreased physical performance can predict overreaching.…”

Section: Introductionmentioning

confidence: 99%

Physical fitness, hormonal, and immunological responses during prolonged military field training

2018

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Physical fitness is crucial to warfighters’ performance in the battlefield. Previous studies have shown negative changes in their hormonal and neuromuscular responses induced by military field training (MFT). The purpose of this study was to investigate the changes in hormonal and immunological values and body composition during a prolonged MFT and to find out how warfighters’ physical condition influences these changes. Conscripts (n = 49, age 20 ± 1 years, height 179 ± 9 cm, body mass 73.8 ± 7.8 kg, fat 12.6 ± 3.7% and BMI 23 kg/m²) were measured before, during, after MFT, and after a 4‐day recovery period. Serum insulin‐like growth factor‐1 (IGF‐1), tumor necrosis factor alpha (TNF‐α), interleukin‐6 (IL‐6) concentrations, creatine kinase (CK) activity and leptin concentration were analyzed as well as body composition throughout MFT. Neuromuscular performance was assessed via lower and upper body muscle endurance at the beginning of the study. During MFT, there was a significant decrease (P < 0.05) in body mass (2.3%), fat mass (7.7%) and in muscle mass (2.2%), but all of these values recovered to PRE‐levels after the recovery period. Serum IGF‐1 (22%) and leptin decreased (66%) while CK increased (88%) significantly (P < 0.05) during MFT but recovered at the end of MFT. Upper body dynamic and trunk isometric muscular endurance had a positive correlation (r = 0.37. P < 0.05) with the change in IGF‐1 during MFT and a negative correlation with the changes in CK (−0.34, P < 0.05). The results show that there were negative changes in conscript's body composition and hormonal and immunological values during the prolonged MFT. These changes suggest that the physiological stress was high during MFT. High levels of upper body and trunk muscular strength were negatively correlated with warfighters’ physiological effects and should therefore be developed prior to actual deployment to reduce the physical decline experienced during prolonged MFTs.

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Effects of winter military training on energy balance, whole-body protein balance, muscle damage, soreness, and physical performance

Cited by 91 publications

References 27 publications

Increased autophagy signaling but not proteasome activity in human skeletal muscle after prolonged low‐intensity exercise with negative energy balance

Increased autophagy signaling but not proteasome activity in human skeletal muscle after prolonged low‐intensity exercise with negative energy balance

No effect of increasing protein intake during military exercise with severe energy deficit on body composition and performance

Physical fitness, hormonal, and immunological responses during prolonged military field training

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