The effect of protein and amino acid intake on resistance training outcomes in younger and older adults

Abstract

Purpose We investigated the effects of protein/amino acid intake in older and younger adults on changes in the force and velocity of knee extension (KE) power during 16 wk of progressive resistance training (PRT). Methods 31 young (mean age 28.04 ± 3.90 yr, 12 men, 19 women); 32 older (64.32 ± 3.69 yr, 13 men, 19 women) adults underwent PRT by knee extension (KE), leg press, and squat 3 d/wk. Strength and power were assessed using standard methods. Protein and amino acid intake were evaluated using the Nutrition Data System software to assess 3–4 random-day dietary records. Results Mean weight adjusted protein intake was 78.9 g/d for younger adults; 70.8 g/d for older adults (p =0.19). At the end of 16 wks PRT, marked improvements were found in both strength and velocity. Amount of baseline weight-adjusted protein intake did not predict improvement in PRT outcomes except for improvements in bilateral knee extension (p=0.05). Branched chain amino acid intake was also predictive of improvement (p=0.04). Conclusions No meaningful age differences were noted in protein intake In both groups, weight-adjusted protein and branched chain amino acid intake was predictive of improvement in knee strength.