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Cited by 2Muscle metabolism and nutritionSports Performance and TrainingNutrition and Health in Aging

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Protein intake by master swimmers: Implications for practice in Sports Nutrition—A cross-sectional study

Open access
Santos de Souza, Michelle, Zaleski Trindade, Cássia Daniele, Castro, Flávio Antônio de Souza, Buss, Caroline, Schneider, Cláudia Dornelles·2025·Nutrition and Health

Abstract

Background: Proteins are essential for the maintenance, repair, and growth of muscle mass. This is particularly important for master athletes because aging has been associated with loss of muscle mass, function, and strength. Moreover, the timing of intake has been shown important for the best protein utilization. Aim: To analyze timing, quantity, and source of dietary protein in competitive master athletes according to current recommendations. Methods: Twenty-one male master swimmers (47.9 ± 10.0 years; 79.2 ± 6.5 kg; 179.1 ± 5.5 cm; 23.5 ± 4.9% body fat; 73.3 ± 4.2% lean mass) participated in this cross-sectional study. Protein intake was analyzed based on 7-day food records, regarding quantity, timing, and sources of intake. Protein intake was evaluated according to current international sports nutrition guidelines, including the International Society of Sports Nutrition Position Stand. Body fat (%) and lean mass (%) were evaluated using dual-energy X-ray absorptiometry. Results: Participants' mean protein intakes were 1.9 ± 0.5 g/kg/day, 0.6 ± 0.2 g/kg/meal post-training, and 33.5 ± 23.9 g during the pre-sleep period. Daily intake was within the recommended values of 1.4 and 2.0 g/kg/day ( p = 0.01 and 0.147, respectively). Mean pre-sleep intake was within the recommendation values of 30–40 g ( p = 0.28 and 0.147, respectively). Most of the daily protein intake was consumed at lunch (66.7 ± 6.9 g) and dinner (48.0 ± 4.5 g). Regarding protein sources, intakes from animal, vegetal, and supplements were, respectively, 65.7%, 29.2%, and 5.1%. Conclusion: Master swimmers presented a total protein intake within the recommendations for a daily basis, but the majority of intake was at lunch and dinner. Protein intake could be better distributed throughout the day to optimize protein synthesis. Guidance on daily protein intake distribution should be reinforced in clinical practice.

Overview

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TL;DR

In 21 male master swimmers, total daily protein intake averaged 1.9 ± 0.5 g/kg/day, within sports-nutrition recommendations, but intake was concentrated at lunch and dinner and small meals were often below recommended per-meal amounts. Pre-sleep and post-training intakes were generally at or above recommendations, suggesting timing and distribution should be targeted in practice.

Key findings

  • Daily protein intake was 1.9 ± 0.5 g/kg/day, within the recommended 1.4–2.0 g/kg/day (p = 0.01 and 0.147, respectively). Protein sources were 65.7% animal, 29.2% vegetable, and 5.1% supplements (exclusively whey); only 8 of 21 swimmers (38%) consumed supplements.
  • Protein intake was concentrated in lunch and dinner; Table 3 reports lunch at 65.0 ± 17.3 g and dinner at 46.2 ± 11.7 g, with a significant meal effect (p < 0.001, η² = 0.53). Intake at smaller meals (snacks and supper) was below the recommendation for distribution throughout the day (p < 0.05).
  • Post-training protein intake was 0.6 ± 0.2 g/kg/meal, above the 0.25–0.30 g/kg recommendation and approximately twice the recommended amount. Pre-sleep intake was 33.5 ± 23.9 g, within the 30–40 g recommendation (p = 0.28 and 0.147, respectively); 66.7% of swimmers met or exceeded the pre-sleep recommendation.
  • Body composition was 23.5 ± 4.9% body fat and 73.3 ± 4.2% lean mass; mean age was 47.9 ± 10.0 years.

Methods

  • Cross-sectional study of 21 male master swimmers (79.2 ± 6.5 kg; 179.1 ± 5.5 cm) recruited from four sports centers in Porto Alegre, Brazil. Inclusion criteria included male sex, age 25–65 years, swim training at least 3 times/week, at least 2000 m/day per training, regular swim training for the past 2 years, and official competition in the previous year.
  • Protein intake was assessed using 7-consecutive-day food records via the Dietbox smartphone app, with intake expressed as total daily, per meal, post-training, pre-sleep, and by source (animal, vegetable, supplement). Body fat and lean mass were measured by dual-energy X-ray absorptiometry (DXA).
  • Intake was compared with current sports nutrition recommendations (total 1.4–2.0 g/kg/day; 20–25 g/meal; post-exercise 0.25–0.30 g/kg within ≤3 h; pre-sleep 30–40 g up to 2 h before sleep). Generalized estimating equations with Bonferroni post-hoc tested meal differences; one-sample t-tests compared intake with recommendations; significance was p ≤ 0.05. Estimated required sample was 17; final sample was 21, with post hoc statistical power of 0.90.

Limitations

  • The paper states that protein intake was assessed through food records, which are subject to participant reporting, require engagement, and might alter consumption; it also states that the sample size may not be generalizable to all swimmers and that studies with master athletes typically do not present large samples.
  • Evident from the text but not explicitly framed as limitations: the cross-sectional convenience sample was all male, drawn from four sports centers in one city, so findings may not extend to female athletes, other sports, or other regions; self-reported dietary data covered one training week; and only 8 of 21 participants consumed supplements, limiting supplement-related inferences.

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Registry

Crossref · 10.1177/02601060241276918

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Figures

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CC-BY-NC-SA · From the PDF
Figure 1 Post-training, pre-sleep, and daily protein intakes of male master swimmers (gray lines indicate the reference values).
Figure 1 Post-training, pre-sleep, and daily protein intakes of male master swimmers (gray lines indicate the reference values).CC-BY-NC-SA · From the PDF

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Citations

Cites

Research works printed but not linked: 1

  1. de Mello AV, Villarim WLF, Machado AD, et al. (2015) Assessment of body composition and dietary intake of adolescent swimmers. Revista Brasileira de Medicina do Esporte 21(5): 381–385.

Metadata

Authors
Santos de Souza, M., Zaleski Trindade, C. D., Castro, F. A. D. S., Buss, C., & Schneider, C. D.
Affiliations
  • Course of Nutrition, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
  • Aquatic Sports Research Group, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
  • Universidade Federal do Rio Grande do Sul (BR)
  • Universidade Federal de Ciências da Saúde de Porto Alegre (BR)
Corresponding author
Schneider, Cláudia Dornelles
Venue
Nutrition and Health
Published
2024-08-31
Volume
31
Issue
3
Pages
1095-1101
ISSN
  • 0260-1060 (ISSN-L)
  • 2047-945X
OpenAlex
W4402094504
Cited by
2
References
37
Citations by year
2025: 2
FWCI
0.46
Type
journal article
Language
en
Open access
Licence
  • cc-by-nc-sa
  • journals.sagepub.com/page/policies/text-and-data-mining-license (tdm)
Locations
  • Nutrition and Health (publishedVersion)
  • PubMed (publishedVersion)
  • Lume (Universidade Federal do Rio Grande do Sul) (submittedVersion, cc-by-nc-sa)
Funders
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (001)
Topics
  • Health Sciences › Nursing › Nutrition and Dietetics › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Health Sciences › Medicine › Physiology (medical) › Nutrition and Health in Aging
Keywords
protein intake, master swimmers, older athletes, protein timing, protein distribution, protein sources, protein supplements, lean body mass, muscle mass
MeSH terms
Adult, Body Composition, Energy Intake, Cross-Sectional Studies, Diet, Dietary Proteins, Humans, Male, Middle Aged, Swimming, Diet Records, Athletes, Sports Nutritional Physiological Phenomena

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