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Morgan PT, Smeuninx B, Marshall RN, Korzepa M, Quinlan JI, McPhee JS, Breen L. Greater myofibrillar protein synthesis following weight-bearing activity in obese old compared with non-obese old and young individuals. GeroScience 2024; 46:3759-3778. [PMID: 37328646 PMCID: PMC11226697 DOI: 10.1007/s11357-023-00833-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 05/18/2023] [Indexed: 06/18/2023] Open
Abstract
The mechanisms through which obesity impacts age-related muscle mass regulation are unclear. In the present study, rates of integrated myofibrillar protein synthesis (iMyoPS) were measured over 48-h prior-to and following a 45-min treadmill walk in 10 older-obese (O-OB, body fat[%]: 33 ± 3%), 10 older-non-obese (O-NO, 20 ± 3%), and 15 younger-non-obese (Y-NO, 13 ± 5%) individuals. Surface electromyography was used to determine thigh muscle "activation". Quadriceps cross-sectional area (CSA), volume, and intramuscular thigh fat fraction (ITFF) were measured by magnetic resonance imaging. Quadriceps maximal voluntary contraction (MVC) was measured by dynamometry. Quadriceps CSA and volume were greater (muscle volume, Y-NO: 1182 ± 232 cm3; O-NO: 869 ± 155 cm3; O-OB: 881 ± 212 cm3, P < 0.01) and ITFF significantly lower (m. vastus lateralis, Y-NO: 3.0 ± 1.0%; O-NO: 4.0 ± 0.9%; O-OB: 9.1 ± 2.6%, P ≤ 0.03) in Y-NO compared with O-NO and O-OB, with no difference between O-NO and O-OB in quadriceps CSA and volume. ITFF was significantly higher in O-OB compared with O-NO. Relative MVC was lower in O-OB compared with Y-NO and O-NO (Y-NO: 5.5 ± 1.6 n·m/kg-1; O-NO: 3.9 ± 1.0 n·m/kg-1; O-OB: 2.9 ± 1.1 n·m/kg-1, P < 0.0001). Thigh muscle "activation" during the treadmill walk was greater in O-OB compared with Y-NO and O-NO (Y-NO: 30.5 ± 13.5%; O-NO: 35.8 ± 19.7%; O-OB: 68.3 ± 32.3%, P < 0.01). Habitual iMyoPS did not differ between groups, whereas iMyoPS was significantly elevated over 48-h post-walk in O-OB (+ 38.6 ± 1.2%·day-1, P < 0.01) but not Y-NO or O-NO (+ 11.4 ± 1.1%·day-1 and + 17.1 ± 1.1%·day-1, respectively, both P > 0.271). Equivalent muscle mass in O-OB may be explained by the muscle anabolic response to weight-bearing activity, whereas the age-related decline in indices of muscle quality appears to be exacerbated in O-OB and warrants further exploration.
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Affiliation(s)
- Paul T Morgan
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Department of Sport and Exercise Sciences, Institute of Sport, Manchester Metropolitan University, 99 Oxford Road, Manchester, M1 7EL, UK
| | - Benoit Smeuninx
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Monash Institute of Pharmacological Sciences, Monash University, Parkville, VIC, Australia
| | - Ryan N Marshall
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Marie Korzepa
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Jonathan I Quinlan
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- NIHR Birmingham Biomedical Research Centre, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, UK
| | - Jamie S McPhee
- Department of Sport and Exercise Sciences, Institute of Sport, Manchester Metropolitan University, 99 Oxford Road, Manchester, M1 7EL, UK
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- NIHR Birmingham Biomedical Research Centre, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, UK.
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, UK.
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Ferrando AA, Wolfe RR, Hirsch KR, Church DD, Kviatkovsky SA, Roberts MD, Stout JR, Gonzalez DE, Sowinski RJ, Kreider RB, Kerksick CM, Burd NA, Pasiakos SM, Ormsbee MJ, Arent SM, Arciero PJ, Campbell BI, VanDusseldorp TA, Jager R, Willoughby DS, Kalman DS, Antonio J. International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance. J Int Soc Sports Nutr 2023; 20:2263409. [PMID: 37800468 PMCID: PMC10561576 DOI: 10.1080/15502783.2023.2263409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/07/2023] Open
Abstract
Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of literature surrounding the effects of essential amino acid (EAA) supplementation on skeletal muscle maintenance and performance. This position stand is intended to provide a scientific foundation to athletes, dietitians, trainers, and other practitioners as to the benefits of supplemental EAA in both healthy and resistant (aging/clinical) populations. EAAs are crucial components of protein intake in humans, as the body cannot synthesize them. The daily recommended intake (DRI) for protein was established to prevent deficiencies due to inadequate EAA consumption. The following conclusions represent the official position of the Society: 1. Initial studies on EAAs' effects on skeletal muscle highlight their primary role in stimulating muscle protein synthesis (MPS) and turnover. Protein turnover is critical for replacing degraded or damaged muscle proteins, laying the metabolic foundation for enhanced functional performance. Consequently, research has shifted to examine the effects of EAA supplementation - with and without the benefits of exercise - on skeletal muscle maintenance and performance. 2. Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS. 3. The safe upper limit of EAA intake (amount), without inborn metabolic disease, can easily accommodate additional supplementation. 4. At rest, stimulation of MPS occurs at relatively small dosages (1.5-3.0 g) and seems to plateau at around 15-18 g. 5. The MPS stimulation by EAAs does not require non-essential amino acids. 6. Free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein. 7. Repeated EAA-induced MPS stimulation throughout the day does not diminish the anabolic effect of meal intake. 8. Although direct comparisons of various formulas have yet to be investigated, aging requires a greater proportion of leucine to overcome the reduced muscle sensitivity known as "anabolic resistance." 9. Without exercise, EAA supplementation can enhance functional outcomes in anabolic-resistant populations. 10. EAA requirements rise in the face of caloric deficits. During caloric deficit, it's essential to meet whole-body EAA requirements to preserve anabolic sensitivity in skeletal muscle.
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Affiliation(s)
- Arny A. Ferrando
- University of Arkansas for Medical Sciences, Center for Translational Research in Aging and Longevity, Department of Geriatrics, Little Rock, AR, USA
| | - Robert R. Wolfe
- University of Arkansas for Medical Sciences, Center for Translational Research in Aging and Longevity, Department of Geriatrics, Little Rock, AR, USA
| | - Katie R. Hirsch
- University of South Carolina, Department of Exercise Science, Arnold School of Public Health, Columbia, SC, USA
| | - David D. Church
- University of Arkansas for Medical Sciences, Center for Translational Research in Aging and Longevity, Department of Geriatrics, Little Rock, AR, USA
| | - Shiloah A. Kviatkovsky
- University of Arkansas for Medical Sciences, Center for Translational Research in Aging and Longevity, Department of Geriatrics, Little Rock, AR, USA
| | | | - Jeffrey R. Stout
- University of Central Florida, School of Kinesiology and Rehabilitation Sciences, Orlando, FL, USA
| | - Drew E. Gonzalez
- Texas A&M University, Exercise & Sport Nutrition Lab, Department of Kinesiology and Sports Management, College Station, TX, USA
| | - Ryan J. Sowinski
- Texas A&M University, Exercise & Sport Nutrition Lab, Department of Kinesiology and Sports Management, College Station, TX, USA
| | - Richard B. Kreider
- Texas A&M University, Exercise & Sport Nutrition Lab, Department of Kinesiology and Sports Management, College Station, TX, USA
| | - Chad M. Kerksick
- Lindenwood University, Exercise and Performance Nutrition Laboratory, College of Science, Technology, and Health, St Charles, MO, USA
| | - Nicholas A. Burd
- University of Illinois Urbana-Champaign, Department of Kinesiology and Community Health, Urbana, IL, USA
| | - Stefan M. Pasiakos
- National Institutes of Health, Office of Dietary Supplements, Bethesda, MD, USA
| | - Michael J. Ormsbee
- Florida State University, Institute of Sports Sciences and Medicine, Nutrition and Integrative Physiology, Tallahassee, FL, USA
| | - Shawn M. Arent
- University of South Carolina, Department of Exercise Science, Arnold School of Public Health, Columbia, SC, USA
| | - Paul J. Arciero
- University of Pittsburgh, Department of Sports Medicine and Nutrition, Pittsburgh, PA, USA
- Skidmore College, Health and Physiological Sciences, Saratoga Springs, NY, USA
| | - Bill I. Campbell
- University of South Florida, Performance & Physique Enhancement Laboratory, Tampa, FL, USA
| | - Trisha A. VanDusseldorp
- Bonafede Health, LLC, JDS Therapeutics, Harrison, NY, USA
- Jacksonville University, Department of Health and Exercise Sciences, Jacksonville, FL, USA
| | | | - Darryn S. Willoughby
- University of Mary Hardin-Baylor, Human Performance Lab, School of Exercise and Sport Science, Belton, TX, USA
| | - Douglas S. Kalman
- Nova Southeastern University, Dr. Kiran C Patel College of Osteopathic Medicine, Department of Nutrition, Davie, FL, USA
| | - Jose Antonio
- Nova Southeastern University, Department of Health and Human Performance, Davie, FL, USA
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Chapman S, Roberts J, Roberts AJ, Ogden H, Izard R, Smith L, Chichger H, Struszczak L, Rawcliffe AJ. Pre-sleep protein supplementation does not improve recovery from load carriage in British Army recruits (part 2). Front Nutr 2023; 10:1264042. [PMID: 38130446 PMCID: PMC10733965 DOI: 10.3389/fnut.2023.1264042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023] Open
Abstract
British Army basic training (BT) is physically demanding with new recruits completing multiple bouts of physical activity each day with limited recovery. Load carriage is one of the most physically demanding BT activities and has been shown to induce acute exercise-induced muscle damage (EIMD) and impair muscle function. Protein supplementation can accelerate muscle recovery by attenuating EIMD and muscle function loss. This study investigated the impact of an additional daily bolus of protein prior to sleep throughout training on acute muscle recovery following a load carriage test in British Army recruits. Ninety nine men and 23 women (mean ± SD: age: 21.3 ± 3.5 yrs., height: 174.8 ± 8.4 cm, body mass 75.4 ± 12.2 kg) were randomized to dietary control (CON), carbohydrate placebo (PLA), moderate (20 g; MOD) or high (60 g; HIGH) protein supplementation. Muscle function (maximal jump height), perceived muscle soreness and urinary markers of muscle damage were assessed before (PRE), immediately post (POST), 24-h post (24 h-POST) and 40-h post (40 h-POST) a load carriage test. There was no impact of supplementation on muscle function at POST (p = 0.752) or 40 h-POST (p = 0.989) load carriage but jump height was greater in PLA compared to HIGH at 24 h-POST (p = 0.037). There was no impact of protein supplementation on muscle soreness POST (p = 0.605), 24 h-POST (p = 0.182) or 40 h-POST (p = 0.333). All groups had increased concentrations of urinary myoglobin and 3-methylhistidine, but there was no statistical difference between groups at any timepoint (p > 0.05). We conclude that pre-sleep protein supplementation does not accelerate acute muscle recovery following load carriage in British Army recruits during basic training. The data suggests that consuming additional energy in the form of CHO or protein was beneficial at attenuating EIMD, although it is acknowledged there were no statistical differences between groups. Although EIMD did occur as indicated by elevated urinary muscle damage markers, it is likely that the load carriage test was not arduous enough to reduce muscle function, limiting the impact of protein supplementation. Practically, protein supplementation above protein intakes of 1.2 g⸱kg-1⸱day-1 following load carriage over similar distances (4 km) and carrying similar loads (15-20 kg) does not appear to be warranted.
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Affiliation(s)
- Shaun Chapman
- Army Recruit Health and Performance Research, HQ Army Recruiting and Initial Training Command, Medical Branch, UK Ministry of Defence, Upavon, United Kingdom
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, United Kingdom
| | - Justin Roberts
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, United Kingdom
| | - Andrew J. Roberts
- Army Recruit Health and Performance Research, HQ Army Recruiting and Initial Training Command, Medical Branch, UK Ministry of Defence, Upavon, United Kingdom
| | - Henry Ogden
- Army Recruit Health and Performance Research, HQ Army Recruiting and Initial Training Command, Medical Branch, UK Ministry of Defence, Upavon, United Kingdom
| | - Rachel Izard
- Defence Science and Technology, UK Ministry of Defence, Salisbury, United Kingdom
| | - Lee Smith
- Centre for Health, Performance and Wellbeing, Anglia Ruskin University, Cambridge, United Kingdom
| | - Havovi Chichger
- Biomedical Science Research Group, School of Life Science, Anglia Ruskin University, Cambridge, United Kingdom
| | - Lauren Struszczak
- Public Health and Sports Sciences, University of Exeter, Exeter, United Kingdom
| | - Alex J. Rawcliffe
- Army Recruit Health and Performance Research, HQ Army Recruiting and Initial Training Command, Medical Branch, UK Ministry of Defence, Upavon, United Kingdom
- Faculty of Science and Engineering, Anglia Ruskin University, Cambridge, United Kingdom
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Muscle Protein Synthesis Responses Following Aerobic-Based Exercise or High-Intensity Interval Training with or Without Protein Ingestion: A Systematic Review. Sports Med 2022; 52:2713-2732. [PMID: 35675022 PMCID: PMC9585015 DOI: 10.1007/s40279-022-01707-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND Systematic investigation of muscle protein synthesis (MPS) responses with or without protein ingestion has been largely limited to resistance training. OBJECTIVE This systematic review determined the capacity for aerobic-based exercise or high-intensity interval training (HIIT) to stimulate post-exercise rates of MPS and whether protein ingestion further significantly increases MPS compared with placebo. METHODS Three separate models analysed rates of either mixed, myofibrillar, sarcoplasmic, or mitochondrial protein synthesis (PS) following aerobic-based exercise or HIIT: Model 1 (n = 9 studies), no protein ingestion; Model 2 (n = 7 studies), peri-exercise protein ingestion with no placebo comparison; Model 3 (n = 14 studies), peri-exercise protein ingestion with placebo comparison. RESULTS Eight of nine studies and all seven studies in Models 1 and 2, respectively, demonstrated significant post-exercise increases in either mixed or a specific muscle protein pool. Model 3 observed significantly greater MPS responses with protein compared with placebo in either mixed or a specific muscle fraction in 7 of 14 studies. Seven studies showed no difference in MPS between protein and placebo, while three studies reported no significant increases in mitochondrial PS with protein compared with placebo. CONCLUSION Most studies reporting significant increases in MPS were confined to mixed and myofibrillar PS that may facilitate power generating capacity of working skeletal muscle with aerobic-based exercise and HIIT. Only three of eight studies demonstrated significant increases in mitochondrial PS post-exercise, with no further benefits of protein ingestion. This lack of change may be explained by the acute analysis window in most studies and apparent latency in exercise-induced stimulation of mitochondrial PS.
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Gwin JA, Church DD, Hatch-McChesney A, Allen JT, Wilson MA, Varanoske AN, Carrigan CT, Murphy NE, Margolis LM, Carbone JW, Wolfe RR, Ferrando AA, Pasiakos SM. Essential amino acid-enriched whey enhances post-exercise whole-body protein balance during energy deficit more than iso-nitrogenous whey or a mixed-macronutrient meal: a randomized, crossover study. J Int Soc Sports Nutr 2021; 18:4. [PMID: 33413462 PMCID: PMC7791816 DOI: 10.1186/s12970-020-00401-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023] Open
Abstract
Background The effects of ingesting varying essential amino acid (EAA)/protein-containing food formats on protein kinetics during energy deficit are undetermined. Therefore, recommendations for EAA/protein food formats necessary to optimize both whole-body protein balance and muscle protein synthesis (MPS) during energy deficit are unknown. We measured protein kinetics after consuming iso-nitrogenous amounts of free-form essential amino acid-enriched whey (EAA + W; 34.7 g protein, 24 g EAA sourced from whey and free-form EAA), whey (WHEY; 34.7 g protein, 18.7 g EAA), or a mixed-macronutrient meal (MEAL; 34.7 g protein, 11.4 g EAA) after exercise during short-term energy deficit. Methods Ten adults (mean ± SD; 21 ± 4 y; 25.7 ± 1.7 kg/m2) completed a randomized, double-blind crossover study consisting of three, 5 d energy-deficit periods (− 30 ± 3% of total energy requirements), separated by 14 d. Whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and in response to combination exercise consisting of load carriage treadmill walking, deadlifts, and box step-ups at the end of each energy deficit using L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Treatments were ingested immediately post-exercise. Mixed-muscle protein synthesis (mixed-MPS) was measured during exercise through recovery. Results Change (Δ postabsorptive + exercise to postprandial + recovery [mean treatment difference (95%CI)]) in whole-body (g/180 min) PS was 15.8 (9.8, 21.9; P = 0.001) and 19.4 (14.8, 24.0; P = 0.001) greater for EAA + W than WHEY and MEAL, respectively, with no difference between WHEY and MEAL. ΔPB was − 6.3 (− 11.5, − 1.18; P = 0.02) greater for EAA + W than WHEY and − 7.7 (− 11.9, − 3.6; P = 0.002) greater for MEAL than WHEY, with no difference between EAA + W and MEAL. ΔNET was 22.1 (20.5, 23.8; P = 0.001) and 18.0 (16.5, 19.5; P = 0.00) greater for EAA + W than WHEY and MEAL, respectively, while ΔNET was 4.2 (2.7, 5.6; P = 0.001) greater for MEAL than WHEY. Mixed-MPS did not differ between treatments. Conclusions While mixed-MPS was similar across treatments, combining free-form EAA with whey promotes greater whole-body net protein balance during energy deficit compared to iso-nitrogenous amounts of whey or a mixed-macronutrient meal. Trial registration ClinicalTrials.gov, Identifier no. NCT04004715. Retrospectively registered 28 June 2019, first enrollment 6 June 2019
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Affiliation(s)
- Jess A Gwin
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA.,Oak Ridge Institute for Science and Education, Belcamp, MD, USA
| | - David D Church
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Adrienne Hatch-McChesney
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA
| | - Jillian T Allen
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA.,Oak Ridge Institute for Science and Education, Belcamp, MD, USA
| | - Marques A Wilson
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA
| | - Alyssa N Varanoske
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA.,Oak Ridge Institute for Science and Education, Belcamp, MD, USA
| | - Christopher T Carrigan
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA
| | - Nancy E Murphy
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA
| | - Lee M Margolis
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA
| | - John W Carbone
- School of Health Sciences, Eastern Michigan University, Ypsilanti, MI, USA
| | - Robert R Wolfe
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Arny A Ferrando
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, Center for Translational Research in Aging & Longevity, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Stefan M Pasiakos
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Bldg. 42, Natick, MA, 01760, USA.
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Hinde KL, O'Leary TJ, Greeves JP, Wardle SL. Measuring Protein Turnover in the Field: Implications for Military Research. Adv Nutr 2020; 12:887-896. [PMID: 33079983 PMCID: PMC8166569 DOI: 10.1093/advances/nmaa123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 11/15/2022] Open
Abstract
Protein turnover reflects the continual synthesis and breakdown of body proteins, and can be measured at a whole-body (i.e. aggregated across all body proteins) or tissue (e.g. skeletal muscle only) level using stable isotope methods. Evaluating protein turnover in free-living environments, such as military training, can help inform protein requirements. We undertook a narrative review of published literature with the aim of reviewing the suitability of, and advancements in, stable isotope methods for measuring protein turnover in field research. The 2 primary approaches for measuring protein turnover are based on precursor- and end-product methods. The precursor method is the gold-standard for measuring acute (over several hours) skeletal muscle protein turnover, whereas the end-product method measures chronic (over several weeks) skeletal muscle protein turnover and provides the opportunity to monitor free-living activities. Both methods require invasive procedures such as the infusion of amino acid tracers and muscle biopsies to assess the uptake of the tracer into tissue. However, the end-product method can also be used to measure acute (over 9-24 h) whole-body protein turnover noninvasively by ingesting 15N-glycine, or equivalent isotope tracers, and collecting urine samples. The end-product method using 15N-glycine is a practical method for measuring whole-body protein turnover in the field over short (24 h) time frames and has been used effectively in recent military field research. Application of this method may improve our understanding of protein kinetics during conditions of high physiological stress in free-living environments such as military training.
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Affiliation(s)
- Katrina L Hinde
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
| | - Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom,Division of Surgery & Interventional Science, University College London, London, United Kingdom
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom,Division of Surgery & Interventional Science, University College London, London, United Kingdom,Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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Huecker M, Sarav M, Pearlman M, Laster J. Protein Supplementation in Sport: Source, Timing, and Intended Benefits. Curr Nutr Rep 2020; 8:382-396. [PMID: 31713177 DOI: 10.1007/s13668-019-00293-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE OF REVIEW The purpose of this review is to provide background on the present literature regarding the utility and effectiveness of protein supplements, including protein source and nutrient timing. RECENT FINDINGS In the setting of adequate dietary protein consumption, research suggests some benefit particularly in sport or exercise activities. Protein supplements command a multi-billion-dollar market with prevalent use in sports. Many individuals, including athletes, do not consume optimal dietary protein on a daily basis. High-protein diets are remarkably safe in healthy subjects, especially in the short term. Some objective outcomes are physiologic and may not translate to clinically relevant outcomes. Athletes should, however, consider long-term implications when consuming high quantities of protein in dietary or supplement form.
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Affiliation(s)
- Martin Huecker
- Dept of Emergency Medicine, University of Louisville School of Medicine, 530 S Jackson St C1H17, Louisville, KY, 40202, USA.
| | - Menaka Sarav
- Division of Nephrology and Hypertension, NorthShore University HealthSystem-University of Chicago, Pritzker School of Medicine, Chicago, IL, USA
| | - Michelle Pearlman
- Department of Medicine, Division of Gastroenterology & Hepatology, University of Miami Health Systems, Miller School of Medicine, Miami, FL, USA
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8
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Effects of high versus standard essential amino acid intakes on whole-body protein turnover and mixed muscle protein synthesis during energy deficit: A randomized, crossover study. Clin Nutr 2020; 40:767-777. [PMID: 32768315 DOI: 10.1016/j.clnu.2020.07.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 01/01/2023]
Abstract
BACKGROUND & AIMS Consuming 0.10-0.14 g essential amino acids (EAA)/kg/dose (0.25-0.30 g protein/kg/dose) maximally stimulates muscle protein synthesis (MPS) during energy balance. Whether consuming EAA beyond that amount enhances MPS and whole-body anabolism following energy deficit is unknown. The aims of this study were to determine the effects of standard and high EAA ingestion on mixed MPS and whole-body protein turnover following energy deficit. DESIGN Nineteen males (mean ± SD; 23 ± 5 y; 25.4 ± 2.7 kg/m2) completed a randomized, double-blind crossover study consisting of two, 5-d energy deficits (-30 ± 4% of total energy requirements), separated by 14-d. Following each energy deficit, mixed MPS and whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and post-resistance exercise (RE) using primed, constant L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Beverages providing standard (0.1 g/kg, 7.87 ± 0.87 g) or high (0.3 g/kg, 23.5 ± 2.54 g) EAA were consumed post-RE. Circulating EAA were measured. RESULTS Postabsorptive mixed MPS (%/h) at rest was not different (P = 0.67) between treatments. Independent of EAA, postprandial mixed MPS at rest (standard EAA, 0.055 ± 0.01; high EAA, 0.061 ± 0.02) and post-RE (standard EAA, 0.055 ± 0.01; high EAA, 0.065 ± 0.02) were greater than postabsorptive mixed MPS at rest (P = 0.02 and P = 0.01, respectively). Change in (Δ postabsorptive) whole-body (g/180 min) PS and PB was greater for high than standard EAA [mean treatment difference (95% CI), 3.4 (2.3, 4.4); P = 0.001 and -15.6 (-17.8, -13.5); P = 0.001, respectively]. NET was more positive for high than standard EAA [19.0 (17.3, 20.7); P = 0.001]. EAA concentrations were greater in high than standard EAA (P = 0.001). CONCLUSIONS These data demonstrate that high compared to standard EAA ingestion enhances whole-body protein status during underfeeding. However, the effects of consuming high and standard EAA on mixed MPS are the same during energy deficit. CLINICAL TRIAL REGISTRY NCT03372928, https://clinicaltrials.gov.
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9
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Chapman S, Roberts J, Smith L, Rawcliffe A, Izard R. Sex differences in dietary intake in British Army recruits undergoing phase one training. J Int Soc Sports Nutr 2019; 16:59. [PMID: 31823790 PMCID: PMC6905050 DOI: 10.1186/s12970-019-0327-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/26/2019] [Indexed: 01/15/2023] Open
Abstract
Background British Army Phase One training exposes men and women to challenging distances of 13.5 km·d− 1 vs. 11.8 km·d− 1 and energy expenditures of ~ 4000 kcal·d− 1 and ~ 3000 kcal·d− 1, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women. Method Researcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes. Results Estimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day− 1, p < 0.001). Both sexes under consumed carbohydrate (CHO) when data was expressed relative to body mass with men consuming a greater amount than women (4.8 ± 1.3 vs. 3.8 ± 1.4 g·kg− 1·day− 1, p = 0.025, ES = 0.74). Both sexes also failed to meet MDRVs for protein intake with men consuming more than women (1.5 ± 0.3 vs. 1.3 ± 0.3 g·kg− 1·day− 1, p > 0.030, ES = 0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg− 1·day− 1, p = 0.483, ES = 0.00). Conclusions Daily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations.
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Affiliation(s)
- Shaun Chapman
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK. .,Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England.
| | - Justin Roberts
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England
| | - Lee Smith
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England
| | - Alex Rawcliffe
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK
| | - Rachel Izard
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK
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10
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The Muscle Protein Synthetic Response to Meal Ingestion Following Resistance-Type Exercise. Sports Med 2019; 49:185-197. [DOI: 10.1007/s40279-019-01053-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Margolis LM, Carbone JW, Berryman CE, Carrigan CT, Murphy NE, Ferrando AA, Young AJ, Pasiakos SM. Severe energy deficit at high altitude inhibits skeletal muscle mTORC1-mediated anabolic signaling without increased ubiquitin proteasome activity. FASEB J 2018; 32:fj201800163RR. [PMID: 29878853 DOI: 10.1096/fj.201800163rr] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
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)Ser2448, p-p70 ribosomal protein S6 kinase (p70S6K)Ser424/421, and p-ribosomal protein S6 (rpS6)Ser235/236 were similar and higher ( P < 0.05) than Base. At acute HA, Post p-mTORSer2448 and Post and REC p-p70S6KSer424/421 were not different from Base and lower than SL ( P < 0.05). At chronic HA, Post and Rec p-mTORSer2448 and p-p70S6KSer424/421 were not different from Base and lower than SL, and, independent of time, p-rpS6Ser235/236 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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Affiliation(s)
- Lee M Margolis
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA
| | - John W Carbone
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA
- School of Health Sciences, Eastern Michigan University, Ypsilanti, Michigan, USA
| | - Claire E Berryman
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA
| | - Christopher T Carrigan
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Nancy E Murphy
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
| | - Arny A Ferrando
- Department of Geriatrics, The Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute of Aging, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Andrew J Young
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA
| | - Stefan M Pasiakos
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
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12
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Margolis LM, Murphy NE, Carrigan CT, McClung HL, Pasiakos SM. Ingesting a Combined Carbohydrate and Essential Amino Acid Supplement Compared to a Non-Nutritive Placebo Blunts Mitochondrial Biogenesis-Related Gene Expression after Aerobic Exercise. Curr Dev Nutr 2017; 1:e000893. [PMID: 29955707 PMCID: PMC5998348 DOI: 10.3945/cdn.117.000893] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/06/2017] [Accepted: 05/22/2017] [Indexed: 01/10/2023] Open
Abstract
Background: Whether load carriage (LC), an endurance exercise mode composed of the aerobic component of traditional endurance exercise [e.g., cycle ergometry (CE)] and contractile forces characteristic of resistive-type exercise, modulates acute mitochondrial adaptive responses to endurance exercise and supplemental nutrition [carbohydrate + essential amino acids (CHO+EAA)] is not known. Objective: The aim of this study was to examine the effects of LC and CE, with or without CHO+EAA supplementation, on acute markers of mitochondrial biogenesis. Methods: Twenty-five adults performed 90 min of metabolically matched LC (treadmill walking, wearing a vest equal to 30% of body mass) or CE exercise during which CHO+EAA (46 g carbohydrate and 10 g essential amino acids) or non-nutritive control (CON) drinks were consumed. Muscle biopsy samples were collected at rest (pre-exercise), post-exercise, and after 3 h of recovery to assess citrate synthase activity and the expression of mRNA (reverse transcriptase-quantitative polymerase chain reaction) and protein (Western blot). Results: Citrate synthase and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK)Thr180/Tyr182 were elevated postexercise compared with pre-exercise (time main effect, P < 0.05). Peroxisome proliferator-activated γ-receptor coactivator 1α (PGC-1α) expression was highest after recovery for CE compared with LC (exercise-by-time effect, P < 0.05). Sirtuin 1 (SIRT1) expression postexercise was higher for CON than for CHO+EAA treatments (drink-by-time, P < 0.05). Tumor suppressor p53 (p53), mitochondrial transcription factor A (TFAM), and cytochrome c oxidase subunit IV (COXIV) expression was greater for CON than for CHO+EAA treatments (drink main effect, P < 0.05). PGC-1α and p53 expressions were positively associated (P < 0.05) with TFAM (r = 0.629 and 0.736, respectively) and COXIV (r = 0.465 and 0.461, respectively) expressions. Conclusions: Acute mitochondrial adaptive responses to endurance exercise appear to be largely driven by exogenous nutrition availability. Although CE upregulated PGC-1α expression to a greater extent than LC, downstream signaling was the same between modes, suggesting that LC, in large part, elicits the same acute mitochondrial response as traditional, non-weight-bearing endurance exercise. This trial was registered at clinicaltrials.gov as NCT01714479.
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Affiliation(s)
- Lee M Margolis
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN
| | - Nancy E Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
| | - Christopher T Carrigan
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN
| | - Holly L McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
| | - Stefan M Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
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13
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Margolis LM, McClung HL, Murphy NE, Carrigan CT, Pasiakos SM. Skeletal Muscle myomiR Are Differentially Expressed by Endurance Exercise Mode and Combined Essential Amino Acid and Carbohydrate Supplementation. Front Physiol 2017; 8:182. [PMID: 28386239 PMCID: PMC5362638 DOI: 10.3389/fphys.2017.00182] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/09/2017] [Indexed: 11/13/2022] Open
Abstract
Skeletal muscle microRNAs (myomiR) expression is modulated by exercise, however, the influence of endurance exercise mode, combined with essential amino acid and carbohydrate (EAA+CHO) supplementation are not well defined. This study determined the effects of weighted versus non-weighted endurance exercise, with or without EAA+CHO ingestion on myomiR expression and their association with muscle protein synthesis (MPS). Twenty five adults performed 90 min of metabolically-matched (2.2 VO2 L·m-1) load carriage (LC; performed on a treadmill wearing a vest equal to 30% of individual body mass) or cycle ergometry (CE) exercise, during which EAA+CHO (10 g EAA and 46 g CHO) or non-nutritive control (CON) drinks were consumed. Expression of myomiR (RT-qPCR) were determined at rest (PRE), immediately post-exercise (POST), and 3 h into recovery (REC). Muscle protein synthesis (2H5-phenylalanine) was measured during exercise and recovery. Relative to PRE, POST, and REC expression of miR-1-3p, miR-206, miR-208a-5, and miR-499 was lower (P < 0.05) for LC compared to CE, regardless of dietary treatment. Independent of exercise mode, miR-1-3p and miR-208a-5p expression were lower (P < 0.05) after ingesting EAA+CHO compared to CON. Expression of miR-206 was highest for CE-CON than any other treatment (exercise-by-drink, P < 0.05). Common targets of differing myomiR were identified as markers within mTORC1 signaling, and miR-206 and miR-499 were inversely associated with MPS rates immediately post-exercise. These findings suggest the alterations in myomiR expression between exercise mode and EAA+CHO intake may in part be due to differing MPS modulation immediately post-exercise.
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Affiliation(s)
- Lee M Margolis
- Military Nutrition Division, US Army Research Institute of Environmental MedicineNatick, MA, USA; Oak Ridge Institute for Science and EducationOak Ridge, TN, USA
| | - Holly L McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine Natick, MA, USA
| | - Nancy E Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine Natick, MA, USA
| | - Christopher T Carrigan
- Military Nutrition Division, US Army Research Institute of Environmental MedicineNatick, MA, USA; Oak Ridge Institute for Science and EducationOak Ridge, TN, USA
| | - Stefan M Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine Natick, MA, USA
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14
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Pasiakos SM, Margolis LM, Murphy NE, McClung HL, Martini S, Gundersen Y, Castellani JW, Karl JP, Teien HK, Madslien EH, Stenberg PH, Young AJ, Montain SJ, McClung JP. Effects of exercise mode, energy, and macronutrient interventions on inflammation during military training. Physiol Rep 2016; 4:4/11/e12820. [PMID: 27273884 PMCID: PMC4908496 DOI: 10.14814/phy2.12820] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/07/2016] [Indexed: 01/28/2023] Open
Abstract
Load carriage (LC) exercise may exacerbate inflammation during training. Nutritional supplementation may mitigate this response by sparing endogenous carbohydrate stores, enhancing glycogen repletion, and attenuating negative energy balance. Two studies were conducted to assess inflammatory responses to acute LC and training, with or without nutritional supplementation. Study 1: 40 adults fed eucaloric diets performed 90-min of either LC (treadmill, mean ± SD 24 ± 3 kg LC) or cycle ergometry (CE) matched for intensity (2.2 ± 0.1 VO2peak L min(-1)) during which combined 10 g protein/46 g carbohydrate (223 kcal) or non-nutritive (22 kcal) control drinks were consumed. Study 2: 73 Soldiers received either combat rations alone or supplemented with 1000 kcal day(-1) from 20 g protein- or 48 g carbohydrate-based bars during a 4-day, 51 km ski march (~45 kg LC, energy expenditure 6155 ± 515 kcal day(-1) and intake 2866 ± 616 kcal day(-1)). IL-6, hepcidin, and ferritin were measured at baseline, 3-h post exercise (PE), 24-h PE, 48-h PE, and 72-h PE in study 1, and before (PRE) and after (POST) the 4-d ski march in study 2. Study 1: IL-6 was higher 3-h and 24-h post exercise (PE) for CE only (mode × time, P < 0.05), hepcidin increased 3-h PE and recovered by 48-h, and ferritin peaked 24-h and remained elevated 72-h PE (P < 0.05), regardless of mode and diet. Study 2: IL-6, hepcidin and ferritin were higher (P < 0.05) after training, regardless of group assignment. Energy expenditure (r = 0.40), intake (r = -0.26), and balance (r = -0.43) were associated (P < 0.05) with hepcidin after training. Inflammation after acute LC and CE was similar and not affected by supplemental nutrition during energy balance. The magnitude of hepcidin response was inversely related to energy balance suggesting that eating enough to balance energy expenditure might attenuate the inflammatory response to military training.
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Affiliation(s)
- Stefan M Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Lee M Margolis
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Nancy E Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Holy L McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Svein Martini
- Norwegian Defence Research Establishment, Kjeller, Norway
| | | | - John W Castellani
- Thermal Mountain and Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - James P Karl
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Hilde K Teien
- Norwegian Defence Research Establishment, Kjeller, Norway
| | | | - Pal H Stenberg
- General Defence Material/Catering and Combat Feeding Section, Norwegian Navy, Rødskiferveien, Norway
| | - Andrew J Young
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Scott J Montain
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - James P McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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