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

Abstract

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.