Dietary Effects on Exercising Muscle Metabolism and Performance by 31P-MRS.
Final rept. for 1993,
NAVAL HEALTH RESEARCH CENTER SAN DIEGO CA
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To determine how diet modulates short-term exercise capacity, skeletal muscle pH, and bioenergetic state were examined by 31P-magnetic resonance spectroscopy MRS in nine healthy volunteers. Subjects performed incremental quadriceps exercise to exhaustion following 5 day of high-CHO HCHO or high-fat HFAT diet which were randomly assigned in cross-over fashion and separated by a 2.5 day period of ad libitum mixed diet. Simultaneous measurements were made of pulmonary gas exchange, minute ventilation, and quadriceps muscle pH and phosphorylation potential. At rest and peak exercise, respiratory exchange ratio and VE were higher following HCHO vs. HFAT pO.O5 reflecting greater CHO utilization. VO2 peak was not increased after HCHO pO.O5, but exercise duration was 339 or - 34 vs. 3O8 or -25 sec, HCHO vs. HFAT p0.05. HCHO was associated with a blunted early fall Of PCPi vs. VO2 -4.1 10-2 or - 0.7 102 vs, 5.6.10-2 or - 10-2 mincc, HCHO vs. HFAT p0.05. On both study days, the slope of PCP vs. V02, before and after the PC threshold, was correlated with exercise time. The results suggest that a diet rich CHO improves exercise efficiency through beneficial effects on intracellular phosphorylation potential.
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