[Serum levels and urinary excretion of amino acids during high intensity physical exertion in healthy men].

The authors investigated the effect of a physical load on a bicycle ergometer on serum concentrations and urinary excretion of 19 amino acids. The initial load of 1 W/kg was increased after 5-minute intervals by 10-20 W to achieve the maximum after 50 minutes exercise. During the last 2-3 minutes of the maximal load a spiroergometric examination was made. The serum alanine concentration increased under these conditions significantly from 474 +/- 133 to 739 +/- 171 mumol/l (p less than 0.001), while the serum threonine concentration declined significantly from 155 +/- 39 to 143 +/- 37 mumol/l (p less than 0.05). Urinary excretion and renal clearance of amino acids declined significantly (p less than 0.05-0.001). The authors found a significant correlation between the drop of the urinary excretion and the rise of serum concentration of alanine (p less than 0.05). The drop of the urinary alanine excretion can contribute to its elevated serum concentration. The fractional amino acid excretions did not decline and the decline of amino acid and creatinine clearances was more or less proportional. The authors conclude that the decline of amino acid excretion is directly associated with a drop of glomerular filtration. The revealed, correlations between the drop of gin, lys, pala, thr and Na excretion suggest that the sodium transport through the nephron can influence the transport of these amino acids.