Energy balance and body composition during US Army special forces training

2013 ◽  
Vol 38 (4) ◽  
pp. 396-400 ◽  
Author(s):  
Lee M. Margolis ◽  
Jennifer Rood ◽  
Catherine Champagne ◽  
Andrew J. Young ◽  
John W. Castellani
Keyword(s):  
Body Composition ◽  
Energy Balance ◽  
Body Mass ◽  
Skinfold Thickness ◽  
High Energy ◽  
Negative Energy ◽  
Fat Free Mass ◽  
Energy Deficit ◽  
Special Forces ◽  
Small Unit

Small Unit Tactics (SUT) is a 64-day phase of the Special Forces Qualification Course designed to simulate real-world combat operations. Assessing the metabolic and physiological responses of such intense training allows greater insights into nutritional requirements of soldiers during combat. The purpose of this study was to examine energy balance around specific training events, as well as changes in body mass and composition. Data were collected from 4 groups of soldiers (n = 36) across 10-day periods. Participants were 28 ± 5 years old, 177 ± 6 cm tall, and weighed 83 ± 7 kg. Doubly labeled water (D218O) was used to assess energy expenditure. Energy intake was calculated by subtracting energy in uneaten foods from known energy in distributed foods in individually packaged combat rations or in the dining facility. Body composition was estimated from skinfold thickness measurements on days 0 and 64 of the course. Simulated urban combat elicited that largest energy deficit (11.3 ± 2.3 MJ·day−1 (2700 ± 550 kcal·day−1); p < 0.05), and reduction in body mass (3.3 ± 1.9 kg; p < 0.05), during SUT, while energy balance was maintained during weapons familiarization training and platoon size raids. Over the entire course body mass decreased by 4.2 ± 3.7 kg (p < 0.01), with fat mass decreasing by 2.8 ± 2.0 kg (p < 0.01) and fat-free mass decreasing by 1.4 ± 2.8 kg (p < 0.05). The overall reduction in body mass suggests that soldiers were in a negative energy balance during SUT, with high energy deficit being observed during strenuous field training.

Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction

2007 ◽  
Vol 103 (1) ◽  
pp. 340-346 ◽  
Author(s):  
Bradley C. Nindl ◽  
Joseph A. Alemany ◽  
Mark D. Kellogg ◽  
Jennifer Rood ◽  
Steven A. Allison ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Mass ◽  
Binding Protein ◽  
Fat Free Mass ◽  
Retinol Binding Protein ◽  
Energy Deficit ◽  
Igf I ◽  
Igf Binding ◽  
Acid Labile Subunit ◽  
Acid Labile

Insulin-like growth factor (IGF)-I is a biomarker that may have greater utility than other conventional nutritional biomarkers in assessing nutritional, health, and fitness status. We hypothesized that the IGF-I system would directionally track a short-term energy deficit and would be more related to changes in body composition than other nutritional biomarkers. Thirty-five healthy men (24 ± 0.3 yr) underwent 8 days of exercise and energy imbalance. Total and free IGF-I, IGF binding proteins-1, -2, and -3, the acid labile subunit, transferrin, ferritin, retinol binding protein, prealbumin, testosterone, triiodothyronine, thyroxine, and leptin responses were measured. Dual-energy X-ray absorptiometry assessed changes in body mass and composition. Repeated-measures ANOVA, correlation analysis, and receiver operator characteristic curves were used for statistical analyses ( P ≤ 0.05). Body mass (−3.8%), fat-free mass (−2.2%), and fat mass (−12.9%) all decreased. Total and free IGF-I, IGF binding protein-3, and the acid labile subunit and prealbumin, but not transferrin, retinol-binding protein, and ferritin, directionally tracked the energy deficit and losses in body composition. The correlation ( r = 0.43) between changes in free IGF-I and body and fat-free mass was the only significant association observed. Receiver operator characteristic curve analysis revealed that a baseline value < 1.67 for the molar volume ratio of IGF-I to acid labile subunit had an area under the curve of 0.745 and was a significant discriminator for those subjects losing >5% body mass. The IGF-I system is an important adjunct in the overall assessment of adaptation to stress imposed by high levels of physical activity superimposed on energy and sleep restriction and is more closely associated with losses in body mass and fat-free mass than other conventional nutritional biomarkers.

scholarly journals Metabolic adaptations during negative energy balance and their potential impact on appetite and food intake

2019 ◽  
Vol 78 (3) ◽  
pp. 279-289 ◽  
Author(s):  
Nuno Casanova ◽  
Kristine Beaulieu ◽  
Graham Finlayson ◽  
Mark Hopkins
Keyword(s):  
Weight Loss ◽  
Energy Balance ◽  
Food Intake ◽  
Negative Energy ◽  
Fat Free Mass ◽  
Negative Energy Balance ◽  
Energy Deficit ◽  
Behavioural Responses ◽  
Compensatory Responses ◽  
Metabolic Adaptations

This review examines the metabolic adaptations that occur in response to negative energy balance and their potential putative or functional impact on appetite and food intake. Sustained negative energy balance will result in weight loss, with body composition changes similar for different dietary interventions if total energy and protein intake are equated. During periods of underfeeding, compensatory metabolic and behavioural responses occur that attenuate the prescribed energy deficit. While losses of metabolically active tissue during energy deficit result in reduced energy expenditure, an additional down-regulation in expenditure has been noted that cannot be explained by changes in body tissue (e.g. adaptive thermogenesis). Sustained negative energy balance is also associated with an increase in orexigenic drive and changes in appetite-related peptides during weight loss that may act as cues for increased hunger and food intake. It has also been suggested that losses of fat-free mass (FFM) could also act as an orexigenic signal during weight loss, but more data are needed to support these findings and the signalling pathways linking FFM and energy intake remain unclear. Taken together, these metabolic and behavioural responses to weight loss point to a highly complex and dynamic energy balance system in which perturbations to individual components can cause co-ordinated and inter-related compensatory responses elsewhere. The strength of these compensatory responses is individually subtle, and early identification of this variability may help identify individuals that respond well or poorly to an intervention.

scholarly journals Higher Usual Energy Intake, Body Mass, Body Mass Index, and Fat Free Mass Index Are Associated with Lower Attrition from an Arduous Military Selection Course (P23-005-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Emily Farina ◽  
Lauren Thompson ◽  
Joseph Knapik ◽  
Stefan Pasiakos ◽  
James McClung ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Composition ◽  
Strength Training ◽  
Aerobic Exercise ◽  
Energy Intake ◽  
Body Mass ◽  
Fat Mass ◽  
Smokeless Tobacco ◽  
Fat Free Mass ◽  
Energy Deficit

Abstract Objectives To determine whether usual energy intake and body composition are associated with attrition from an arduous military selection course characterized by energy deficit and strenuous physical events, including fitness tests, loaded road marches, runs, land navigation, and an obstacle course. Methods Energy intake and body composition were assessed in U.S. Army Soldiers (n = 776) at the start of a military assessment and selection course. Usual energy intake (kcal) over the previous year was estimated from a 127-item Block food frequency questionnaire. Body composition measures, including body mass (kg), body mass index (BMI, body mass in kg/height in m2), fat free mass index (FFMI, fat free mass in kg/height in m2), and fat mass index (FMI, fat mass in kg/height in m2) were assessed by calibrated scale and 3-site skinfold caliper measures. Associations between energy intake, body composition, and demographics were determined with analysis of variance. Logistic regression was used to determine likelihood of attrition [odds ratio (OR), 95% confidence interval (CI)] based on quartiles of energy intake and body composition. Models were adjusted for age, education, duration of aerobic exercise, duration of strength training, smoking status, and smokeless tobacco use. Results Soldiers that were younger (18–24 y), engaged in longer duration of aerobic exercise (≥200 min/wk) and strength training (≥400 min/wk), had more education (≥some college), and were smokeless tobacco users had higher energy intakes (P < 0.05). Higher energy intake was associated with higher body mass and FFMI (P < 0.05). After adjustment, Soldiers with higher energy intake, body mass, BMI, and FFMI were less likely to fail the strenuous course (Q1 vs. Q2, Q3, and Q4: OR range = 0.25–0.54; 95% CI lower bound range = 0.15–0.33; 95% CI upper bound range = 0.46–0.87). FMI was not associated with attrition. Conclusions Optimization of body composition by adequate consumption of calories prior to a physically demanding military selection course may be associated with reduced attrition. Funding Sources Supported by U.S. Army Medical Research and Materiel Command. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Army or the Department of Defense. Supporting Tables, Images and/or Graphs

scholarly journals Case Study of a Female Ocean Racer: Prerace Preparation and Nutritional Intake During the Vendée Globe 2008

2012 ◽  
Vol 22 (3) ◽  
pp. 212-219 ◽  
Author(s):  
Deborah Fearnley ◽  
Louise Sutton ◽  
John O’Hara ◽  
Amy Brightmore ◽  
Roderick King ◽  
...  
Keyword(s):  
Energy Balance ◽  
Body Mass ◽  
Negative Energy ◽  
Fat Free Mass ◽  
Nutritional Intake ◽  
Health It ◽  
Multimethod Approach ◽  
Food Diaries ◽  
Nutritional Strategies

The Vendée Globe is a solo round-the-world sailing race without stopovers or assistance, a physically demanding challenge for which appropriate nutrition should maintain energy balance and ensure optimum performance. This is an account of prerace nutritional preparation with a professional and experienced female racer and assessment of daily nutritional intake (NI) during the race using a multimethod approach. A daily energy intake (EI) of 15.1 MJ/day was recommended for the race and negotiated down by the racer to 12.7 MJ/day, with carbohydrate and fluid intake goals of 480 g/day and 3,020 ml/day, respectively. Throughout the 99-day voyage, daily NI was recorded using electronic food diaries and inventories piloted during training races. NI was assessed and a postrace interview and questionnaire were used to evaluate the intervention. Fat mass (FM) and fat-free mass (FFM) were assessed pre- (37 days) and postrace (11 days) using dual-energy X-ray absorptiometry, and body mass was measured before the racer stepped on the yacht and immediately postrace. Mean EI was 9.2 MJ/day (2.4–14.3 MJ/day), representing a negative energy balance of 3.5 MJ/day under the negotiated EI goal, evidenced by a 7.9-kg loss of body mass (FM –7.5 kg, FFM –0.4 kg) during the voyage, with consequent underconsumption of carbohydrate by ~130 g/day. According to the postrace yacht food inventory, self-reported EI was underreported by 7%. This intervention demonstrates the practicality of the NI approach and assessment, but the racer’s nutrition strategy can be further improved to facilitate meeting more optimal NI goals for performance and health. It also shows that evaluation of NI is possible in this environment over prolonged periods, which can provide important information for optimizing nutritional strategies for ocean racing.

Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity

2008 ◽  
Vol 105 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Joseph A. Alemany ◽  
Bradley C. Nindl ◽  
Mark D. Kellogg ◽  
William J. Tharion ◽  
Andrew J. Young ◽  
...  
Keyword(s):  
Body Composition ◽  
Energy Expenditure ◽  
Protein Content ◽  
Energy Intake ◽  
Dietary Protein ◽  
High Energy ◽  
Low Energy ◽  
Fat Free Mass ◽  
Energy Deficit ◽  
Igf I

Energy restriction coupled with high energy expenditure from arduous work is associated with an altered insulin-like growth factor-I (IGF-I) system and androgens that are coincident with losses of fat-free mass. The aim of this study was to determine the effects of two levels of dietary protein content and its effects on IGF-I, androgens, and losses of fat-free mass accompanying energy deficit. We hypothesized that higher dietary protein content would attenuate the decline of anabolic hormones and, thus, prevent losses of fat-free mass. Thirty-four men [24 (SD 0.3) yr, 180.1 (SD 1.1) cm, and 83.0 (SD 1.4) kg] participated in an 8-day military exercise characterized by high energy expenditure (16.5 MJ/day), low energy intake (6.5 MJ/day), and sleep deprivation (4 h/24 h) and were randomly divided into two dietary groups: 0.9 and 0.5 g/kg dietary protein intake. IGF-I system analytes, androgens, and body composition were assessed before and on days 4 and 8 of the intervention. Total, free, and nonternary IGF-I and testosterone declined 50%, 64%, 55%, and 45%, respectively, with similar reductions in both groups. There was, however, a diet × time interaction on day 8 for total IGF-I and sex hormone-binding globulin. Decreases in body mass (3.2 kg), fat-free mass (1.2 kg), fat mass (2.0 kg), and percent body fat (1.5%) were similar in both groups ( P = 0.01). Dietary protein content of 0.5 and 0.9 g/kg minimally attenuated the decline of IGF-I, the androgenic system, and fat-free mass during 8 days of negative energy balance associated with high energy expenditure and low energy intake.

scholarly journals Energy balance at high altitude of 6,542 m

1994 ◽  
Vol 77 (2) ◽  
pp. 862-866 ◽  
Author(s):  
K. R. Westerterp ◽  
B. Kayser ◽  
L. Wouters ◽  
J. L. Le Trong ◽  
J. P. Richalet
Keyword(s):  
Body Composition ◽  
Energy Balance ◽  
Metabolic Rate ◽  
High Altitude ◽  
Body Mass ◽  
Basal Metabolic Rate ◽  
Gas Analysis ◽  
Activity Level ◽  
Energy Deficit ◽  
Bomb Calorimetry

Weight loss due to malnutrition and possibly intestinal malabsorption is a well-known phenomenon in high-altitude climbers. Up to approximately 5,000 m, energy balance may be attained and intestinal energy digestibility remains normal. To see whether 1) energy balance may also be attained at 6,542 m and, if not, 2) whether decreased energy digestibility would play a significant role in the energy deficit, energy intake (EI), energy expenditure, body composition, and energy digestibility of 10 subjects (4 women, 6 men; 27–44 yr) were assessed during a 21-day sojourn on the summit of Mt. Sajama, Bolivia (6,542 m). EI was measured during two 3-day intervals: EI1 (days 7–9) and EI2 (days 17–19). Total fecal energy loss during EI1 was calculated from fecal energy measured by bomb calorimetry. Average daily metabolic rate (ADMR) at altitude was measured in six subjects (2 women, 4 men) using doubly labeled water over a 10-day interval (days 9–19). Basal metabolic rate was measured before and after the expedition by respiratory gas analysis. Body composition was estimated from skinfolds and body mass before and during the altitude sojourn. Subjects were in negative energy balance throughout the observation period (EI1-ADMR = -2.9 +/- 1.8 MJ/day and EI2-ADMR = -2.3 +/- 1.8 MJ/day based on a gross energy digestibility of 95%). The activity level, expressed as ADMR to basal metabolic rate, was 1.56–2.39. The loss of fat mass (3.7 +/- 1.5 kg) represented 74 +/- 15% of the loss of body mass.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effects of Testosterone Supplementation on Ghrelin and Appetite During and After Severe Energy Deficit in Healthy Men

2020 ◽  
Vol 4 (4) ◽  
Author(s):  
J Philip Karl ◽  
Claire E Berryman ◽  
Melissa N Harris ◽  
Harris R Lieberman ◽  
Kishore M Gadde ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Mass ◽  
Phase 1 ◽  
Secondary Analysis ◽  
Free Testosterone ◽  
Fat Free Mass ◽  
Energy Deficit ◽  
Double Blind ◽  
Healthy Men ◽  
Acyl Ghrelin

Abstract Background Severe energy deficits cause interrelated reductions in testosterone and fat free mass. Testosterone supplementation may mitigate those decrements, but could also reduce circulating concentrations of the orexigenic hormone ghrelin, thereby exacerbating energy deficit by suppressing appetite. Objective To determine whether testosterone supplementation during severe energy deficit influences fasting and postprandial ghrelin concentrations and appetite. Design and methods Secondary analysis of a randomized, double-blind trial that determined the effects of testosterone supplementation on body composition changes during and following severe energy deficit in nonobese, eugonadal men. Phase 1 (PRE-ED): 14-day run-in; phase 2: 28 days, 55% energy deficit with 200 mg testosterone enanthate weekly (TEST; n = 24) or placebo (PLA; n = 26); phase 3: free-living until body mass recovered (end-of-study; EOS). Fasting and postprandial acyl ghrelin and des-acyl ghrelin concentrations and appetite were secondary outcomes measured during the final week of each phase. Results Fasting acyl ghrelin concentrations, and postprandial acyl and des-acyl ghrelin concentrations increased in PLA during energy deficit then returned to PRE-ED values by EOS, but did not change in TEST (phase-by-group, P &lt; 0.05). Correlations between changes in free testosterone and changes in fasting acyl ghrelin concentrations during energy deficit (ρ = -0.42, P = 0.003) and body mass recovery (ρ = -0.38; P = 0.01) were not mediated by changes in body mass or body composition. Transient increases in appetite during energy deficit were not affected by testosterone treatment. Conclusions Testosterone supplementation during short-term, severe energy deficit in healthy men prevents deficit-induced increases in circulating ghrelin without blunting concomitant increases in appetite. Clinical Trials Registration www.clinicaltrials.gov NCT02734238 (registered 12 April 2016).

scholarly journals Somatotipo, composição corporal e desempenho em ultramaratona

2016 ◽  
Vol 18 (2) ◽  
pp. 127 ◽  
Author(s):  
Taisa Belli ◽  
Cláudio Luiz de Souza Meireles ◽  
Mônica De Oliveira Costa ◽  
Marco Aurélio Ackermann ◽  
Claudio Alexandre Gobatto
Keyword(s):  
Body Mass Index ◽  
Body Composition ◽  
Waist Circumference ◽  
Body Mass ◽  
Negative Impact ◽  
Skinfold Thickness ◽  
Fat Free Mass ◽  
Lower Limbs ◽  
Mean Values ◽  
Fat Deposits

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p127 This study aimed to characterize somatotype, analyze anthropometric indicators associated with body composition during the race and verify possible relationships with the performance of athletes in a 217-km ultramarathon. For this, ten male volunteers (42.8 ± 3.5 years; 171.4 ± 1.9 cm height, 70.7 ± 3.1 kg body mass; 15 ± 3 years of running exercise) performed a critical velocity (CV) test one week before the competition and were submitted to anthropometric measurements before, at 84 km of the race and at the end of the race. Volunteers finished the race in 46.8 ± 3.4 h (4.9 ± 0.4 km / h; 33.4 ± 1.8% CV). Mean values equivalent to somatotype components accounted for 3.4 ± 0.4 for endomorphy, 5.2 ± 0.4 for mesomorphy and 1.7 ± 0.3 for ectomorphy. Body mass, body mass index, fat-free mass and chest circumference decreased (P <0.05) after 84 and 217 km compared to baseline. Pre-race values of thigh skinfold thickness (R = 0.79) and waist circumference (R = 0.64) were significantly correlated (P <0.05) with final race time. Thus, we concluded that ultramarathoners had mean endo-mesomorph somatotype and reductions in both body mass and fat-free mass during and after the race. Furthermore, the results suggest that increased body fat deposits concentrated in the lower limbs and abdominal region may have a negative impact on the performance of the athletes in 217-km ultramarathon.

Fat-free body mass from skinfold thickness: a close relationship with total body nitrogen

1978 ◽  
Vol 39 (2) ◽  
pp. 403-405 ◽  
Author(s):  
G. L. Hill ◽  
J. A. Bradley ◽  
J. P. Collins ◽  
I. McCarthy ◽  
C. B. Oxby ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Mass ◽  
Close Correlation ◽  
Skinfold Thickness ◽  
Fat Free Mass ◽  
Wide Range ◽  
Close Relationship ◽  
Simple Measurement ◽  
Free Body ◽  
Total Body

Fat-free body mass is an important component of body composition which is of particular interest to nutritionists and related workers. Fat-free mass has been determined from the simple measurement of skinfold thickness and it has been demonstrated that there is a close correlation with total body nitrogen even though the test subjects had a wide range of nutritional status.

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