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Changing arterial oxygen content (C(aO(2))) has a highly sensitive influence on the rate of peripheral locomotor muscle fatigue development. We examined the effects of C(aO(2)) on exercise performance and its interaction with peripheral quadriceps fatigue. Eight trained males performed four 5 km cycling time trials (power output voluntarily adjustable) at(More)
We hypothesized that during exercise at maximal O2 consumption (VO2max), high demand for respiratory muscle blood flow (Q) would elicit locomotor muscle vasoconstriction and compromise limb Q. Seven male cyclists (VO2max 64 +/- 6 ml.kg-1.min-1) each completed 14 exercise bouts of 2.5-min duration at VO2max on a cycle ergometer during two testing sessions.(More)
We examined the effects of hypoxia severity on peripheral versus central determinants of exercise performance. Eight cyclists performed constant-load exercise to exhaustion at various fractions of inspired O2 fraction (FIO2 0.21/0.15/0.10). At task failure (pedal frequency < 70% target) arterial hypoxaemia was surreptitiously reversed via acute O2(More)
We evaluated the effects of a 5 week (25 sessions); (30-35 min/day, 5 days/week), respiratory muscle training (RMT) program in nine competitive male cyclists. The experimental design included inspiratory resistance strength training (3-5 min/session) and hyperpnea endurance training (30 min/session), a placebo group which used a sham hypoxic trainer (n=8),(More)
We investigated the influence of group III/IV muscle afferents on peripheral fatigue, central motor drive (CMD) and endurance capacity during high-intensity leg-cycling. In a double-blind, placebo-controlled design, seven males performed constant-load cycling exercise (318 ± 9 W; 80% of peak power output (W(peak))) to exhaustion under placebo conditions and(More)
The response of the pulmonary system to exercise is well-documented to be quite precise in its homeostatic regulation, highly efficient in terms of its physiologic cost, and operating well within its maximum reserves. Two exceptions to these generalizations are documented here in the highly-trained athlete: 1) the arterial hypoxemia observed in short-term(More)
We subjected 29 healthy young women (age: 27 +/- 1 yr) with a wide range of fitness levels [maximal oxygen uptake (VO2 max): 57 +/- 6 ml . kg-1 . min-1; 35-70 ml . kg-1 . min-1] to a progressive treadmill running test. Our subjects had significantly smaller lung volumes and lower maximal expiratory flow rates, irrespective of fitness level, compared with(More)
We determined the effects of exercise on active expiration and end-expiratory lung volume (EELV) during steady-state exercise in 13 healthy subjects. We also addressed the questions of what affects active expiration during exercise. Exercise effects on EELV were determined by a He-dilution technique and verified by changes in end-expiratory esophageal(More)
We investigated the role of somatosensory feedback from locomotor muscles on central motor drive (CMD) and the development of peripheral fatigue during high-intensity endurance exercise. In a double-blind, placebo-controlled design, eight cyclists randomly performed three 5 km time trials: control, interspinous ligament injection of saline (5K(Plac), L3-L4)(More)
1. We recently showed that fatigue of the inspiratory muscles via voluntary efforts caused a time-dependent increase in limb muscle sympathetic nerve activity (MSNA) (St Croix et al. 2000). We now asked whether limb muscle vasoconstriction and reduction in limb blood flow also accompany inspiratory muscle fatigue. 2. In six healthy human subjects at rest,(More)