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Cited by 33Muscle metabolism and nutritionNutrition and Health in AgingSports Performance and Training

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Protein Requirements for Master Athletes: Just Older Versions of Their Younger Selves

Open access
Moore, Daniel R.·2021·Sports Medicine

Abstract

It is established that protein requirements are elevated in athletes to support their training and post-exercise recovery and adaptation, especially within skeletal muscle. However, research on the requirements for this macronutrient has been performed almost exclusively in younger athletes, which may complicate their translation to the growing population of Master athletes (i.e. > 35 years old). In contrast to older (> 65 years) untrained adults who typically demonstrate anabolic resistance to dietary protein as a primary mediator of the ‘normal’ age-related loss of muscle mass and strength, Master athletes are generally considered successful models of aging as evidenced by possessing similar body composition, muscle mass, and aerobic fitness as untrained adults more than half their age. The primary physiology changes considered to underpin the anabolic resistance of aging are precipitated or exacerbated by physical inactivity, which has led to higher protein recommendations to stimulate muscle protein synthesis in older untrained compared to younger untrained adults. This review puts forth the argument that Master athletes have similar muscle characteristics, physiological responses to exercise, and protein metabolism as young athletes and, therefore, are unlikely to have protein requirements that are different from their young contemporaries. Recommendations for protein amount, type, and pattern will be discussed for Master athletes to enhance their recovery from and adaptation to resistance and endurance training.

Overview

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TL;DR

This narrative review argues that Master athletes (>35 years) are not simply older versions of untrained older adults: they largely avoid age-related anabolic resistance and appear to have protein requirements similar to younger athletes. It recommends applying current younger-athlete protein targets, with meal-focused intakes of ~0.3–0.5 g/kg and daily intakes around ~1.6–1.8 g/kg/day depending on training mode.

Key findings

  • Master athletes are described as models of successful aging, with body composition, muscle mass, and aerobic fitness generally comparable to untrained adults more than half their age; the review argues they do not show the typical age-related anabolic resistance to dietary protein.
  • In untrained older adults, an estimated average meal protein requirement of ~0.4 g/kg of high-quality leucine-enriched protein is needed to maximize myofibrillar protein synthesis at rest, ~65% greater than in younger adults; after exercise, 20 g whey is sufficient in young trained men, whereas older untrained adults may require up to 40 g.
  • For Master athletes, the review recommends resistance training post-exercise protein of ~0.3–0.4 g/kg per meal and a daily target of ~1.6 g/kg/day; endurance training post-exercise protein of ~0.5 g/kg per meal and a daily target of ~1.8 g/kg/day, consumed as 4–5 equally spaced meals.
  • Low-carbohydrate availability training may increase daily protein requirements by ~10–15%, and plant-based proteins may warrant a ~10% higher intake; Master athletes are reported to self-report lower post-exercise meal protein intakes than younger athletes (e.g., ~0.4 vs. ~0.3 g/kg, respectively).

Methods

  • Narrative review synthesizing evidence on protein requirements, anabolic resistance, digestion/absorption, amino acid delivery and uptake, mTORC1 signaling, inflammation, sex differences, and bone health in aging and athletic populations.
  • Focuses primarily on older adults/athletes (>60 years) while defining Master athletes as >35 years; evidence includes acute stable isotope dose–response studies, nitrogen balance, indicator amino acid oxidation, and training studies.
  • No new primary data are presented; recommendations are extrapolated from younger athletes and older untrained adults because direct Master athlete protein dose–response studies are lacking.

Limitations

  • The paper states that studies investigating post-exercise ingested bolus protein dose–response in Master athletes do not currently exist, and that additional research is needed, especially in females and postmenopausal women.
  • The paper notes that studies often do not consistently report baseline physical activity or fitness, making some comparisons indirect; evidence from geographical activity differences is suggestive rather than definitive.
  • Evident from the text: this is a narrative review without a systematic search or meta-analysis, and many recommendations rely on extrapolation from younger athletes or older untrained adults rather than direct Master athlete data.

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Integrity signals

Registry

Crossref · 10.1007/s40279-021-01510-0

Cites

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Statistics

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Figures

Fig. 1 a Myofibrillar protein synthesis after an acute bout of resistance exercise and graded intakes of whey protein in young trained [21] and older untrained [19] adults. Doses with different letters are significantly from each other within a population. b Data from these same publications [19, 21] expressed as the increase in myofibrillar protein synthesis after resistance exercise from a protein-free control against the body weight-normalized whey protein intake. Shaded area highlights the relative anabolic resistance of the untrained older adults. FSR fractional synthesis rate
Fig. 1 a Myofibrillar protein synthesis after an acute bout of resistance exercise and graded intakes of whey protein in young trained [21] and older untrained [19] adults. Doses with different letters are significantly from each other within a population. b Data from these same publications [19, 21] expressed as the increase in myofibrillar protein synthesis after resistance exercise from a protein-free control against the body weight-normalized whey protein intake. Shaded area highlights the relative anabolic resistance of the untrained older adults. FSR fractional synthesis rateCC BY · PubMed Central
Fig. 2 Myofibrillar protein synthesis after resistance exercise in response to dietary protein ingestion in young adults [78] and untrained older adults in different geographical locations who may have relatively higher [77] or lower [19] habitual activity levels. Data are normalized to the maximal myofibrillar protein synthetic response within each study (i.e. data span) assuming a maximal response at the highest intake (40–45 g of protein or > 0.49 g/kg). Error bars have not been included due to the requirement to normalize intakes and percentage of maximal response to reported mean group values from the respective publications. FSR fractional synthesis rate
Fig. 2 Myofibrillar protein synthesis after resistance exercise in response to dietary protein ingestion in young adults [78] and untrained older adults in different geographical locations who may have relatively higher [77] or lower [19] habitual activity levels. Data are normalized to the maximal myofibrillar protein synthetic response within each study (i.e. data span) assuming a maximal response at the highest intake (40–45 g of protein or > 0.49 g/kg). Error bars have not been included due to the requirement to normalize intakes and percentage of maximal response to reported mean group values from the respective publications. FSR fractional synthesis rateCC BY · PubMed Central
Fig. 3 Schematic representation of the activity-related differences in muscle morphology a between Master athletes and older untrained adults that would influence the rested or post-exercise increase in muscle protein synthesis after meal protein ingestion (b). ‘Anabolic resistance’ is a rightward shift in the protein dose–response curve that is characteristic of an inactive lifestyle, especially with aging. Shaded area represents the meal protein intake that would maximize muscle protein synthesis yet minimize dietary amino acid oxidation in Master athletes
Fig. 3 Schematic representation of the activity-related differences in muscle morphology a between Master athletes and older untrained adults that would influence the rested or post-exercise increase in muscle protein synthesis after meal protein ingestion (b). ‘Anabolic resistance’ is a rightward shift in the protein dose–response curve that is characteristic of an inactive lifestyle, especially with aging. Shaded area represents the meal protein intake that would maximize muscle protein synthesis yet minimize dietary amino acid oxidation in Master athletesCC BY · PubMed Central
Fig. 4 Schematic representation of the meal protein distribution pattern to optimize muscle protein synthesis after exercise (running caricature) in Master athletes. Solid line represents fasted muscle protein synthesis. Dashed lines represent an optimal meal protein-induced enhancement of muscle protein synthesis. Active caricature represents an exercise stimulus
Fig. 4 Schematic representation of the meal protein distribution pattern to optimize muscle protein synthesis after exercise (running caricature) in Master athletes. Solid line represents fasted muscle protein synthesis. Dashed lines represent an optimal meal protein-induced enhancement of muscle protein synthesis. Active caricature represents an exercise stimulusCC BY · PubMed Central

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Metadata

Authors
Moore, D. R.
Affiliations
University of Toronto (CA)
Corresponding author
Moore, Daniel R.
Venue
Sports Medicine
Published
2021-09
Volume
51
Issue
S1
Pages
13-30
ISSN
  • 0112-1642 (ISSN-L)
  • 1179-2035
OpenAlex
W3200315391
Cited by
33
References
183
Citations by year
2026: 7 · 2025: 9 · 2024: 2 · 2023: 6 · 2022: 7 · 2021: 2
FWCI
0.53
Type
journal article
Language
en
Open access
Licence
Locations
  • Sports Medicine (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • PubMed Central (publishedVersion, cc-by)
  • TSpace (University of Toronto) (acceptedVersion, cc-by)
Funders
Gatorade Sport Science Institute
Topics
  • Health Sciences › Nursing › Nutrition and Dietetics › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Physiology (medical) › Nutrition and Health in Aging
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
Keywords
protein requirements, master athletes, aging, anabolic resistance, muscle protein synthesis, post-exercise recovery, resistance training, endurance training, protein metabolism, older athletes, muscle mass
MeSH terms
Adult, Aged, Aging, Body Composition, Humans, Physical Endurance, Exercise, Muscle, Skeletal, Athletes

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