EFFECT OF CARBOHYDRATE SUPPLEMENTATION ON PLASMA GLUTAMINE DURING PROLONGED EXERCISE AND RECOVERY

Muscle glycogen and glucose have been suggested to be carbon-chain pre cursors for glutamine synthesis in skeletal muscle. Therefore, the aim of the present study is to investigate whether carbohydrate supplemen tation affects plasma glutamine and other amino acids during exercise and 7 h of recovery. Eight well-trained subjects cycled at an alternat ing workload of 50 and 80% W-max until exhaustion (59 to 140 min). Dur ing the exercise bout the subjects received either water (control) or a carbohydrate (CHO) drink (83 g CHO.l(-1), 2 ml.kg(-1) per kg body we ight every 15 min). Plasma glutamine concentration appeared not to be affected by exercise, as a significant increase was only observed at s ome points in time during the control test. During recovery, however, plasma glutamine concentration decreased from 682 +/- 24 and 685 +/- 1 9 mu mol.l(-1) at exhaustion to 552 +/- 19 and 534 +/- 12 mu mol.l(-1) after 2 h of recovery for the control and CHO test, respectively. Pla sma glutamine concentration returned to pre-exercise values after 7 h of recovery. Alanine concentration increased during exercise in both t ests. During the recovery period the concentration of alanine (48%), a nd total amino acids (23%) decreased below the pre-exercise level. The plasma alanine and the total amino acid concentration was still suppr essed after 7 h of recovery. In conclusion, carbohydrate supplementati on had neither an effect during exercise nor during recovery on the co ncentration of plasma glutamine or other amino acids. Exercise, howeve r, causes a substantial decrease in the plasma amino acid concentratio n during recovery.