The effect of daily protein supplementation, with or without resistance training for 1 year, on muscle size, strength, and function in healthy older adults: a randomized controlled trial

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Authors

  • Kenneth H Mertz
  • Søren Reitelseder
  • Rasmus Bechshoeft
  • Jacob Bulow
  • Grith Højfeldt
  • Mikkel Jensen
  • Simon R Schacht
  • Mads Vendelbo Lind
  • Morten A Rasmussen
  • Ulla R Mikkelsen
  • Inge Tetens
  • Søren B Engelsen
  • Dennis S Nielsen
  • Astrid P Jespersen

Colleges, School and Institutes

External organisations

  • Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark
  • Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
  • Vitality Centre for Good Older Lives, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
  • Department of Food Science, University of Copenhagen, 1958 Copenhagen, Denmark.
  • Arla Foods Ingredients Group P/S, Viby J, Denmark.
  • Copenhagen Center for Health Research in the Humanities, The SAXO Institute, University of Copenhagen, Copenhagen SV, Denmark.

Abstract

Background: Protein supplementation alone or combined with resistance training has been proposed to be effective in counteracting age-related losses of muscle mass and strength.

Objectives: To investigate the effect of protein supplementation alone or combined with light-intensity or heavy-load resistance exercise on muscle size, strength, and function in older adults.

Methods: In a 1-y randomized controlled trial, 208 healthy older adults (>65 y) were randomly assigned to 1 of 5 interventions: 1) carbohydrate supplementation (CARB); 2) collagen protein supplementation (COLL); 3) whey protein supplementation (WHEY); 4) light-intensity resistance training 3–5 times/wk with whey protein supplementation (LITW); and 5) heavy resistance training 3 times weekly with whey protein supplementation (HRTW). Protein supplements contained 20 g protein + 10 g carbohydrate, whereas CARB contained 30 g of carbohydrates. All intervention groups received the supplement twice daily. The primary outcome was change in the quadriceps cross-sectional area (qCSA). Secondary outcomes included measures of lower extremity strength and power, functional capabilities, and body composition.

Results: There were 184 participants who completed the study. COLL and WHEY did not affect any measured parameter compared to CARB. Compared to WHEY, HRTW improved the qCSA size (between-group difference, +1.68 cm2; 95% CI, +0.41 to +2.95 cm2; P = 0.03), as well as dynamic (+18.4 Nm; 95% CI, +10.1 to +26.6 Nm; P < 10−4) and isometric knee extensor strength (+23.9 Nm; 95% CI, +14.2 to +33.6 Nm; P < 10−5). LITW did not improve the qCSA size, but increased dynamic knee extensor strength compared to WHEY (+13.7 Nm; 95% CI, +5.3 and +22.1 Nm; P = 0.01).

Conclusions: Recommending protein supplementation as a stand-alone intervention for healthy older individuals seems ineffective in improving muscle mass and strength. Only HRTW was effective in both preserving muscle mass and increasing strength. Thus, we recommend that future studies investigate strategies to increase long-term compliance to heavy resistance exercise in healthy older adults. This trial was registered at clinicaltrials.gov as NCT02034760.

Details

Original languageEnglish
JournalThe American journal of clinical nutrition
Early online date10 Feb 2021
Publication statusE-pub ahead of print - 10 Feb 2021

Keywords

  • protein supplementation, ageing, skeletal muscle, resistance training, randomized controlled trials, exercise