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Effect of vitamin B-6 supplementation on fuels, catecholamines, and amino acids during exercise in men
R S Virk1, N J Dunton, J C Young
1Department of Nutrition and Food Management, Oregon State University, Corvallis 97331, USA.
Purpose:
In two separate but identical studies, the effect of vitamin B-6 supplementation 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% VO2max during two separate 9-d controlled diet periods. Exercise test 1 (T1C) occurred following a control diet, and test 2 (T2B6) occurred following 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 over time in both tests (P < 0.001) and were lower in T2B6 compared to T1C at pre (P = 0.03), during (P = 0.05), and post-60 min (P = 0.04) of exercise. Mean lactate, glycerol, and catecholamine concentrations only changed over time (P < 0.0001). The only significant changes in amino acid concentrations were for lower tyrosine (P = 0.007) and methionine (P = 0.03) concentrations in T2B6 relative to TIC at post-60 min of exercise and postexercise, respectively. No differences were observed in exercise times to exhaustion between TIC (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 acid concentrations during exhaustive endurance exercise without affecting endurance.