Effects of a daily mixed nutritional supplement on physical performance, body composition, and circulating anabolic hormones during 8 weeks of arduous military training

Fortes, Matthew B.; Diment, Bethany C.; Greeves, Julie P.; Casey, Albert E.; Izard, Rachel; Walsh, Neil P.

doi:10.1139/h11-124

Cited by 37 publications

(69 citation statements)

References 31 publications

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“…The participants in both groups consumed, however, only 57±13% of the provided energy during TC. The difference of this study to the previously published energy supplements studies during short-term military field training [12], [14], [15], [24]–[26] is the use of protein-rich supplement. However, like the previous studies, also in this study the use of supplements increased energy intake, although it could not prevent from energy deficit.…”

Section: Discussionmentioning

confidence: 85%

“…Furthermore, energy balance is an important factor in sustaining training load and maintaining high performance during strenuous military training [13]–[15]. Demanding training is risk factor for upper respiratory tract infection (URTI) among athletes [16] and soldiers [17], and energy deficit has been hypothesized to be one reason for URTI [18], however, scientific evidence is lacking.…”

Section: Introductionmentioning

confidence: 99%

“…There are few published energy supplements studies during military field training in purpose to assure energy balance [12], [14], [15], [24]–[26], however, none of this have used protein-rich supplement. Thus the aim of this study was to determine the effects of an additional easy-to-use protein-rich energy bar supplement of 4.1 MJ·d −1 on energy balance, physical activity, body composition, physical performance and subjective experiences of hunger, URTI, mood state and overall well-being during the 8-day military training course (TC) in a cold environment.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

et al. 2012

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BackgroundPrevious military studies have shown an energy deficit during a strenuous field training course (TC). This study aimed to determine the effects of energy bar supplementation on energy balance, physical activity (PA), physical performance and well-being and to evaluate ad libitum fluid intake during wintertime 8-day strenuous TC.MethodsTwenty-six men (age 20±1 yr.) were randomly divided into two groups: The control group (n = 12) had traditional field rations and the experimental (Ebar) group (n = 14) field rations plus energy bars of 4.1 MJ•day−1. Energy (EI) and water intake was recorded. Fat-free mass and water loss were measured with deuterium dilution and elimination, respectively. The energy expenditure was calculated using the intake/balance method and energy availability as (EI/estimated basal metabolic rate). PA was monitored using an accelerometer. Physical performance was measured and questionnaires of upper respiratory tract infections (URTI), hunger and mood state were recorded before, during and after TC.ResultsEbar had a higher EI and energy availability than the controls. However, decreases in body mass and fat mass were similar in both groups representing an energy deficit. No differences were observed between the groups in PA, water balance, URTI symptoms and changes in physical performance and fat-free mass. Ebar felt less hunger after TC than the controls and they had improved positive mood state during the latter part of TC while controls did not. Water deficit associated to higher PA. Furthermore, URTI symptoms and negative mood state associated negatively with energy availability and PA.ConclusionAn easy-to-use protein-rich energy bars did not prevent energy deficit nor influence PA during an 8-day TC. The high content of protein in the bars might have induced satiation decreasing energy intake from field rations. PA and energy intake seems to be primarily affected by other factors than energy supplementation such as mood state.

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Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

et al. 2012

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“…During an 8-wk Infantry Battle School in the United Kingdom, 2 groups of soldiers were provided a standard diet; however, a supplement group received an additional 1220 kcal (46 g of protein) during the first 6 wk and an additional 861 kcal (32 g of protein) during the last 2 wk (18). Whereas the supplement blunted the losses of total, lean, and fat mass, it also maintained performance in strength and muscular power (18). The loss of body fat and lean mass in the control group indicates an activity-induced energy deficit; thus, the results point to the caloric advantages conferred by the supplement.…”

Section: Performance Benefits Of Protein Coingestion During Activitymentioning

confidence: 99%

Increased Protein Intake in Military Special Operations

Ferrando

2013

The Journal of Nutrition

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Special operations are so designated for the specialized military missions they address. As a result, special operations present some unique metabolic challenges. In particular, soldiers often operate in a negative energy balance in stressful and demanding conditions with little opportunity for rest or recovery. In this framework, findings inferred from the performance literature suggest that increased protein intake may be beneficial. In particular, increased protein intake during negative caloric balance maintains lean body mass and blood glucose production. The addition of protein to mixed macronutrient supplements is beneficial for muscle endurance and power endpoints, and the use of amino acids improves gross and fine motor skills. Increasing protein intake during periods of intense training and/or metabolic demand improves subsequent performance, improves muscular recovery, and reduces symptoms of psychological stress. Consumption of protein before sleep confers the anabolic responses required for the maintenance of lean mass and muscle recovery.A maximal response in muscle protein synthesis is achieved with the consumption of 20-25 g of protein alone. However, higher protein intakes in the context of mixed-nutrient ingestion also confer anabolic benefits by reducing protein breakdown. Restricted rations issued to special operators provide less than the RDA for protein (;0.6 g/kg), and these soldiers often rely on commercial products to augment their rations. The provision of reasonable alternatives and/or certification of approved supplements by the U.S. Department of Defense would be prudent. J. Nutr. 143: 1852S-1856S, 2013.How ''Special'' Are Special Operations?Whereas units involved in special operations, or SPECOPS 4 as they are commonly known, have proven their mettle and war-fighting benefits to our countryÕs defense throughout our history, it is the uniqueness of their missions that highlights the requirement for nutritional examination. In this regard, nutrition must be viewed not merely in light of the fuel required to power a highly trained soldier, but more importantly, how the soldier can function optimally in the most demanding of environments. Although SPECOPS missions tend to be shorter in duration, the operations tempo (optempo), or the required tactical demands, is normally intense, stressful, and unpredictable. Existing data indicate that SPECOPS soldiers routinely expend >5000 kcal/d during combat operations training (1). As such, scheduled nutritional intake, in the traditional sense of military rations, is virtually impossible to achieve and unavailable in many circumstances. The U.S. Department of Defense (DoD) has planned for such occasions by creating rations specific to the high optempo inherent in SPECOPS. Whereas standard rations, such as ''meals, ready-to-eat,'' are designed to be nutritionally complete and sustain a soldier for #21 d, rations designed for SPECOPS-type scenarios are restricted in nutritional content. According to U.S. Army regulation 40-25 (2), restrict...

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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 . The catabolic state is characterized by disturbances in endocrine functions, including reduced circulating levels of anabolic hormones such as testosterone (TESTO) and insulin‐like growth factor 1 (IGF‐1), and increased levels of catabolic hormones such as cortisol (COR), which correlate well with observed losses in muscle mass during military exercises of both short and long duration.…”

Section: Introductionmentioning

confidence: 99%

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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Effects of a daily mixed nutritional supplement on physical performance, body composition, and circulating anabolic hormones during 8 weeks of arduous military training

Cited by 37 publications

References 31 publications

Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

Increased Protein Intake in Military Special Operations

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

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