Protein Amount, Quality and Distribution in Active Older Adults and Its Effects on Outcomes of Fat Free Mass, Skeletal Muscle Strength and Power

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This study aimed to investigate the associations of habitual protein intake in a cohort of active older adults including: daily relative protein intake, distribution of protein intake across main meals, and number of meals providing ≥0.4 g/kg body mass (BM) on outcomes of fat free mass (FFM), leg power, leg strength, and handgrip strength (HGS). This was a cross-sectional study (2018-2020) where data were obtained and analysed from n= 53 active older adults (≥50 yrs; ≥90 min/week of self-reported physical activity). Daily absolute (g) and relative protein (g/kgBM/day) intake, absolute and relative protein intake per meal, the number of meals that provided 0.4 g/kgBM, and the protein intake distribution were calculated for each participant through a 3-day food diary assessment and analysis. Appendicular muscle mass index (ALM/ht2; dual x-ray absorptiometry), leg strength (1-repetition maximum using leg press), leg power (force plate countermovement jump) and HGS (dynamometer) were assessed. An independent t-test was used to test statistical significance between groups based on protein intake. Pearson’s correlation determined differences between protein intakes with lean muscle mass and strength outcomes. Results:Daily protein intake was (mean ± SD) 1.4 ± 0.4 g/kg BM/day, with the coefficient of variation of main meals calculated at 0.46 (0.41-0.51), and the average number of meals that provided ≥0.4g/kgBM was 1.1 ± 0.8 meals. There was a moderate but significant positive correlation between number of meals per day providing ≥0.4g/kgBM, and number and leg press (r= .301,p< .05), significant for males (r= .591, p= .029), but not females (r=.262, p= .196). There was also a small significant association between the number of total protein and dairy serves per day and leg strength ((r= .290, p= .035; r= .372, p= .006, respectively). No significant correlations were observed for outcomes of HGS or FFM and any of the dietary protein measures. Conclusion: In a cohort of active older adults who achieve greater protein intakes than the current recommendations, a minimum of 1 meal containing ≥0.4 g/kg BM of protein and higher intakes of dairy based foods may be required to achieve favourable outcomes in leg strength.