Effects of Supplemental Energy on Protein Balance during 4-d Arctic Military Training

Margolis, Lee M.; Murphy, Nancy; Martini, Svein; Gundersen, Yngvar; Castellani, John W.; Karl, J. Philip; Carrigan, Christopher T.; Teien, Hilde Kristin; Madslien, Elisabeth Henie; Montain, Scott J.; Pasiakos, Stefan M.

doi:10.1249/mss.0000000000000944

Cited by 53 publications

(95 citation statements)

References 38 publications

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“…Observed changes in endocrine variables in response to the military exercise, such as decreased levels of androgen hormones (TESTO, free TESTO, IGF‐1, TESTO/COR ratio) and pro‐metabolic hormones (T3 and T4) and increased levels of COR, suggest development of a catabolic physiological milieu, resembling observations made in previous studies . This may halt cellular growth and proliferation, while allocating available energy resources toward basal metabolic demands . Accordingly, during the exercise the soldiers were in a maladaptive state, with reduced ability to repair muscle tissue and sustain adequate tissue functions, providing a potential explanation for the observed impairment in physical performance.…”

Section: Discussionsupporting

confidence: 85%

“…Hence, they did not investigate the effect of protein supplement on muscle mass and performance per se , as energy availability is a potent modulator of these variables . Indeed, overall energy intake and corresponding degrees of energy deficiency may be decisive for whole‐body homeostasis rather than the nature of the energy source ingested (eg, protein vs carbohydrate content) . For example, increased protein intake (1 vs 2 g kg −1 d −1 ) does not seem to hinder loss of muscle mass during 21 days of concomitant severe energy deficit (~−70%) and high altitude exposure in recreationally active men .…”

Section: Introductionmentioning

confidence: 99%

“…5,6 Indeed, overall energy intake and corresponding degrees of energy deficiency may be decisive for whole-body homeostasis rather than the nature of the energy source ingested (eg, protein vs carbohydrate content). 17 For example, increased protein intake (1 vs 2 g kg −1 d −1 ) does not seem to hinder loss of muscle mass during 21 days of concomitant severe energy deficit (~−70%) and high altitude exposure in recreationally active men. 18 However, there is evidence to the contrary, as increased protein intake mitigates loss of muscle mass within an isocaloric diet in both resistance-trained subjects and military personnel undergoing 40% energy deficit, respectively.…”

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confidence: 97%

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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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Section: Discussionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 97%

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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 the current study, an HP diet (2.0 g protein/kg) was ineffective in sparing FFM during an ED at HA that was much more severe (—70%) than the 40% ED used in SL studies. Our prior work (40) showed an inability to restore protein and nitrogen balance at SL during ED >40% with dietary protein manipulation alone. The inability of an HP diet to spare FFM in the current study was probably related to the severity of the ED.…”

Section: Discussionmentioning

confidence: 93%

Severe negative energy balance during 21 d at high altitude decreases fat‐free mass regardless of dietary protein intake: a randomized controlled trial

et al. 2018

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In this 2-phase randomized controlled study, we examined whether consuming a higher-protein (HP) diet would attenuate fat-free mass (FFM) loss during energy deficit (ED) at high altitude (HA) in 17 healthy males (mean 6 SD: 23 6 6 yr; 82 6 14 kg). During phase 1 at sea level (SL, 55 m), participants consumed a eucaloric diet providing standard protein (SP; 1.0 g protein/kg,) for 21 d. During phase 2, participants resided at HA (4300 m) for 22 d and were randomly assigned to either an SP or HP (2.0 g protein/kg) diet designed to elicit a 40% ED. Body composition, substrate oxidation, and postabsorptive whole-body protein kinetics were measured. Participants were weight stable during SL and lost 7.9 6 1.9 kg (P < 0.01) during HA, regardless of dietary protein intake. Decrements in wholebody FFM (3.6 6 2.4 kg) and fat mass (3.6 6 1.3 kg) were not different between SP and HP. HP oxidized 0.95 6 0.32 g protein/kg per day more than SP and whole-body net protein balance was more negative for HP than for SP (P < 0.01). Based on changes in body energy stores, the overall ED was 70% (21849 6 511 kcal/d, no group differences). Consuming an HP diet did not protect FFM during severe ED at HA.-Berryman, C. E., Young, A. J., Karl, J. P., Kenefick, R. W., Margolis, L. M., Cole, R. E., Carbone, J. W., Lieberman, H. R., Kim, I.-Y., Ferrando, A. A., Pasiakos, S. M. Severe negative energy balance during 21 d at high altitude decreases fat-free mass regardless of dietary protein intake: a randomized controlled trial. FASEB J. 32, 894-905 (2018 For lowlanders sojourning at high altitude (HA .1500 m), maintaining energy balance can be challenging because of an increase in resting metabolic rate (RMR) (1, 2) and a decrease in appetite (3) caused by physiologic adaptations to hypoxia. The effects of hypoxia on energy balance are frequently compounded by limited access to food and high physical activity levels while at HA. Negative energy balance usually develops at HA and typically leads to weight loss (4). Barnholt et al. (4) showed that individuals sustaining a 40% energy deficit (ED) for 21 d at HA lost more body weight than individuals adhering to the same controlled diet and physical activity at sea level (SL). Furthermore, some studies (5-8) have observed .50% of total body mass (TBM) loss as fat-free mass (FFM) during prolonged ED at HA, which is greater than the 25-35% typically observed at SL (9-11), suggesting protein turnover kinetics and substrate utilization during weight loss at HA may differ from that at SL.At SL, protein intake above the Recommended Dietary Allowance (RDA, 0.8 g protein/kg per day) limits FFM loss during moderate negative energy balance (;40% ED) in healthy, normal weight adults (12)(13)(14). We have shown that consuming a diet containing 1.6 or 2.4 g protein/kg per day (2 and 3 times the RDA, respectively) for 21 d, within the context of a 40% ED, attenuates FFM loss as a percentage of TBM loss (30 6 7 and 36 6 5%, respectively) compared to an isocaloric diet containing 0.8 g protein/kg per d...

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“…Aerobic exercise and muscle biopsy studies were conducted at SL after 7 d of following the weight maintenance diet and again on d 1 (acute HA) and d 22 (chronic HA) at HA. Aerobic exercise was chosen because it represents the primary exercise modality performed by military personnel during strenuous operations (37,38), particularly during missions at HA (27,28). This exercise type, coupled with protein feeding, is sufficient to stimulate mTORC1-mediated anabolic signaling at SL (39)(40)(41)(42).…”

Section: Aerobic Exercise and Muscle Biopsy Studiesmentioning

confidence: 99%

Severe energy deficit at high altitude inhibits skeletal muscle mTORC1‐mediated anabolic signaling without increased ubiquitin proteasome activity

et al. 2018

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Muscle loss at high altitude (HA) is attributable to energy deficit and a potential dysregulation of anabolic signaling. Exercise and protein ingestion can attenuate the effects of energy deficit on muscle at sea level (SL). Whether these effects are observed when energy deficit occurs at HA is unknown. To address this, muscle obtained from lowlanders ( n = 8 males) at SL, acute HA (3 h, 4300 m), and chronic HA (21 d, -1766 kcal/d energy balance) before [baseline (Base)] and after 80 min of aerobic exercise followed by a 2-mile time trial [postexercise (Post)] and 3 h into recovery (Rec) after ingesting whey protein (25 g) were analyzed using standard molecular techniques. At SL, Post, and REC, p-mechanistic target of rapamycin (mTOR), p-p70 ribosomal protein S6 kinase (p70S6K), and p-ribosomal protein S6 (rpS6) were similar and higher ( P < 0.05) than Base. At acute HA, Post p-mTOR and Post and REC p-p70S6K were not different from Base and lower than SL ( P < 0.05). At chronic HA, Post and Rec p-mTOR and p-p70S6K were not different from Base and lower than SL, and, independent of time, p-rpS6 was lower than SL ( P < 0.05). Post proteasome activity was lower ( P < 0.05) than Base and Rec, independent of phase. Our findings suggest that HA exposure induces muscle anabolic resistance that is exacerbated by energy deficit during acclimatization, with no change in proteolysis.-Margolis, L. M., Carbone, J. W., Berryman, C. E., Carrigan, C. T., Murphy, N. E., Ferrando, A. A., Young, A. J., Pasiakos, S. M. Severe energy deficit at high altitude inhibits skeletal muscle mTORC1-mediated anabolic signaling without increased ubiquitin proteasome activity.

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Effects of Supplemental Energy on Protein Balance during 4-d Arctic Military Training

Abstract: These data reinforce the importance of consuming sufficient energy during periods of high energy expenditure to mitigate the consequences of negative energy balance and attenuate whole-body protein loss.

Cited by 53 publications

References 38 publications

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

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

Severe negative energy balance during 21 d at high altitude decreases fat‐free mass regardless of dietary protein intake: a randomized controlled trial

Severe energy deficit at high altitude inhibits skeletal muscle mTORC1‐mediated anabolic signaling without increased ubiquitin proteasome activity

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