Impact of an oral amino acid provision on Achilles peritendinous amino acid concentrations in young and older adults
Recent studies have indicated that consumption of amino acid-rich compounds can increase tendon collagen content and enhance biomechanical function. Still, it is not clear as to what extent oral consumption of amino acids alters peritendinous amino acid concentrations. Whether aging alters the delivery of amino acids to tendon tissue after oral consumption is also not known. Using microdialysis, we determined the impact of a single oral essential amino acid bolus on Achilles peritendinous amino acid concentrations in younger (n=7; 27{+/-}1 yr.) and older adults (n=6; 68{+/-}2 yrs.) over four hours. The peritendinous concentration of all amino acids in the beverage except methionine (p=0.136) and glycine (p=0.087) increased with time (p<0.05). Additionally, the concentrations of glycine and arginine were greater in older adults (p[≤]0.05). We also accessed the impact of amino acid consumption on peritendinous concentrations of pro-collagen I1, a marker of collagen synthesis. Pro-collagen I1 tended to change with time (p=0.071) but was not altered age (p=0.226). We demonstrate that an oral amino acid bolus leads to modest increases in Achilles peritendinous amino acid concentrations in young and older adults. The concentration of some amino acids was also greater in older adults. However, the amino acid bolus did not significantly impact peritendinous pro-collagen concentrations.