Effect of hyperoxia on aerobic and anaerobic performances and muscle metabolism during maximal cycling exercise

Acta Physiol Scand. 2000 Mar;168(3):403-11. doi: 10.1046/j.1365-201x.2000.00648.x.

Abstract

The hyperoxia-improved tolerance to maximal aerobic performance was studied in relation to exercising muscle metabolic state. Five students were submitted to four different tests on a cycle ergometer, each being conducted under normoxia and hyperoxia (60% FiO2) on separate days: Test 1, a progressive exercise until exhaustion to determine the maximal work load (Wmax) which was unchanged by hyperoxia; Test 2, an exercise at Wmax (287 +/- 12 W) until exhaustion to determine the performance time (texh) which was elevated by 38% under hyperoxia but exhaustion occurred at the same arterial proton and lactate concentrations; Test 3 (S-Exercise test) consisted of cycling at Wmax for 90% normoxic-texh (4.8 +/- 0.5 min under both O2 conditions) then followed by a 10-s sprint bout during which the total work output (Wtot) was determined; Wtot was elevated by 15% when exercising under hyperoxia; Test 4 (M-Exercise test) consisted also of cycling at Wmax for 4.8 +/- 0.5 min with blood and muscle samples taken at rest and at the end of the exercise to compare the level of different metabolites. During hyperoxic M-Exercise test, glycogen was twice more depleted whereas glucose-6-phosphate and lactate were less accumulated when compared with normoxia. No significant differences were observed for pyruvate, phosphocreatine and muscle/blood lactate ratio between the two conditions. Conversely to normoxia, levels of ATP, ADP and total NADH were maintained at their resting level under 60% FiO2. These data lead us to suppose a higher oxidation rate for pyruvate and NADH in mitochondria, thereby lowering the metabolic acidosis and allowing a better functioning of the glycolytic and contractile processes to delay the time to exhaustion.

MeSH terms

  • Adult
  • Aerobiosis
  • Anaerobiosis
  • Blood / metabolism
  • Exercise / physiology*
  • Exercise Test
  • Glycolysis
  • Humans
  • Hydrogen-Ion Concentration
  • Hyperoxia / blood
  • Hyperoxia / metabolism*
  • Hyperoxia / physiopathology
  • Lactic Acid / blood
  • Male
  • Muscle Contraction / physiology
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / physiopathology

Substances

  • Lactic Acid