Premium
EFFECTS OF EXERCISE‐INDUCED ARTERIAL HYPOXAEMIA ON LIMB MUSCLE FATIGUE AND PERFORMANCE
Author(s) -
Romer Lee M,
Dempsey Jerome A
Publication year - 2006
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2006.04361.x
Subject(s) - medicine , muscle fatigue , lactate threshold , anaerobic exercise , physical exercise , ventilatory threshold , cardiology , stimulation , physical therapy , anesthesia , vo2 max , blood lactate , heart rate , electromyography , physical medicine and rehabilitation , blood pressure
SUMMARY1 Reductions in arterial O 2 saturation (−5% to −10% S a o 2 below rest) occur over time during sustained heavy‐intensity exercise in a normoxic environment, caused primarily by the effects of acid pH and increased temperature on the position of the HbO 2 dissociation curve. 2 We prevented the desaturation incurred during exercise at ∼90% O 2 MAX via increased fraction of inspired O 2 ( F i o 2 ) (0.23 to 0.29) and showed that exercise time to exhaustion was increased. 3 We used supramaximal magnetic stimulation (1–100 Hz) of the femoral nerve to test for quadriceps fatigue. We used mildly hyperoxic inspirates ( F i o 2 0.23 to 0.29) to prevent O 2 desaturation. We then compared the amount of quadriceps fatigue incurred following cycling exercise at S a o 2 91% vs 98% with each trial carried out at identical work rates and for equal durations. 4 Preventing the normal exercise‐induced O 2 desaturation prevented about one‐half the amount of exercise‐induced quadriceps fatigue; plasma lactate and effort perception were also reduced. In a subset of less fit subjects who showed only minimal arterial hypoxaemia during sustained exercise ( S a o 2 ∼95%), breathing a mildly hypoxic inspirate ( F i o 2 0.17; S a o 2 ∼88%) exacerbated the quadriceps fatigue. 5 We conclude that the normal exercise‐induced O 2 desaturation during heavy‐intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue.