Sparing Effect of Chronic High-Altitude Exposure on Muscle Glycogen Utilization During Exercise,
Abstract
Substrate utilization during heavy (approx. 85% VO2 max) bicycle exercise was examined in eight low-altitude residents at sea level (SL) and after acute (2 hours) and chronic (18 days) exposure to 4,300 m (HA). Mean VO2 max was approx. 27% lower with acute HA than at SL and did not change significantly with continued HA exposure. Biopsies from the vastus lateralis muscle and venous blood samples were obtained before and after 30 min of exercise, while determinations of the respiratory exchange ratio (R) were made at 10 min intervals during each of the submaximal bouts. Resting serum levels of free fatty acids, unchanged with exercise, were 2X and 3X higher than SL with acute and chronic HA, respectively. Exercise did not alter resting serum glycerol levels at SL or during acute HA, but caused an 11-fold increase during chronic HA. Mean blood lactate concentrations were similar following exercise at SL and acute HA but were 87% lower after chronic HA. During exercise at SL and acute HA, the rate of muscle glycogen utilization and R were similar but were 41% and 15% lower, respectively, with chronic HA. These data suggest that after chronic high-altitude exposure, increased mobilization and use of free fatty acids during exercise resulted in sparing of muscle glycogen. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 16, 1981
- Accession Number
- ADA111063
Entities
People
- A. Cymerman
- Aaron J. Young
- J. J. Knapik
- K. B. Pandolf
- W. J. Evans
Organizations
- United States Army Research Institute of Environmental Medicine