Effect of vitamin B-6 supplementation on fuels, catecholamines, and amino acids during exercise in men

Purpose: In two separate but identical studies,the effect of vitamin B-6 su pplementation was examined on plasma energy substrates, catecholamines, and 13 amino acid concentrations during exercise. Methods: Eleven trained men performed two separate exhaustive exercise tests at 71.0 +/- 4.6% (V) over dot O-2max during two separate 9-d controlled diet periods. Exercise test 1 (T1C) occurred following a control diet, and test 2 (T2B6) occurred follow ing a vitamin B-6 supplemented diet (20 mg PN.d(-1)). Blood was drawn pre, during (60 min), post, and post-60 min of exercise, and plasma was analyzed for glucose, lactate, glycerol, free fatty acids (FFA), catecholamines (N = 5), and amino acids (N = 5). Results: Mean FFA concentrations changed ove rtime in both tests (P < 0.001) and were lower in T2B6 compared to T1C at p re (P = 0.03), during (P = 0.05), and post-60 min (P = 0.04) of exercise. M ean lactate, glycerol, and catecholamine concentrations only changed over t ime (P < 0.0001). The only significant changes in amino acid concentrations were for lower tyrosine(P = 0.007) and methionine (P = 0.03) concentration s in T2B6 relative to T1C at post-60 min of exercise and postexercise, resp ectively. No differences were observed in exercise times to exhaustion betw een T1C (108+32.6 min) and T2B6 (109+51.2 min). Conclusions: These results indicate that vitamin B-6 supplementation can alter plasma FFA and amino ac id concentrations during exhaustive endurance exercise without affecting en durance.