Oxygen Uptake, Muscle High‐Energy Phosphates, and Lactate in Exercise under Acute Hypoxic Conditions in Man

Publisher Website
Google Scholar
Abstract
The relationships among muscle metabolite concentration, exercise intensity, and oxygen utilization were studied under simulated altitude conditions (decompression chamber, 462 mm Hg b.p.). 5 male subjects exercised in 4 min bouts on a cycle ergometer at a wide range of exercise intensities (range 20–114% altitude max Vo2). Oxygen uptake was determined throughout exercise and recovery. Muscle biopsies (vastus lateralis) and fingertip blood samples were taken at rest and during recovery. Muscle ATP and creatine phosphate concentrations became reduced during exercise at all intensities. Little or no increase in lactate was observed below apprpx. 60% altitude max Vo2. The hypoxic condition caused a decreased acceleration from resting Vo2 and an increase in O2‐deficit at each absolute intensity as compared with normoxia. Close relationships were observed between level of high‐energy phosphate depletion and both O2‐deficit and fast component of O2‐debt not different from the same relationships under normoxic conditions. Virtually all differences in physiological response to identical exercise intensities at altitude as compared to normoxia were appropriately adjusted by expressing exercise intensity relative to the respective aerobic power capacities in the two conditions. Physiological responses to this type of exercise appear determined in great part by the availability of oxygen.

This publication has 8 references indexed in Scilit: