Our aim was to isolate the independent effects of 1) inspiratory muscle work (W(b)) and 2) arterial hypoxemia during heavy-intensity exercise in acute hypoxia on locomotor muscle fatigue. Eight cyclists exercised to exhaustion in hypoxia [inspired O(2) fraction (Fi(O(2))) = 0.15, arterial hemoglobin saturation (Sa(O(2))) = 81 +/- 1%; 8.6 +/- 0.5 min, 273 +/- 6 W; Hypoxia-control (Ctrl)] and at ...

Chronic reductions in tissue O(2) tension (hypoxia) are associated with muscle atrophy and blunted hypertrophic responses to resistance exercise (RE) training. However, the effect of hypoxia on muscle protein synthesis (MPS) at rest and after RE is unknown. In a crossover study, seven healthy men (21.4 ± 0.7 yr) performed unilateral leg RE (6 × 8 repetitions at 70% 1-repetition maximum) under n...

The aim of the present study was to evaluate the efficacy of 3-week high intensity interval training in normobaric hypoxia (IHT) on aerobic capacity in basketball players. Twelve male well trained basketball players, randomly divided into a hypoxia (H) group (n=6; age: 22±1.6 years; VO2max: 52.6±3.9 ml/kg/min; body height - BH: 188.8±6.1 cm; body mass - BM: 83.9±7.2 kg; % of body fat - FAT%: 11...

PlanHab is a planetary habitat simulation study. The atmosphere within future space habitats is anticipated to have reduced Po2, but information is scarce as to how physiological systems may respond to combined exposure to moderate hypoxia and reduced gravity. This study investigated, using a randomized-crossover design, how insulin sensitivity, glucose tolerance, and circulating lipids were af...

BACKGROUND It is well known that hypoxic exercise in healthy individuals increases limb blood flow, leg oxygen extraction and limb vascular conductance during knee extension exercise. However, the effect of hypoxia on cardiac output, and total vascular conductance is less clear. Furthermore, the oxygen delivery response to hypoxic exercise in well trained individuals is not well known. Therefor...

Exercise blunts sympathetic alpha-adrenergic vasoconstriction (functional sympatholysis). We hypothesized that sympatholysis would be augmented during hypoxic exercise compared with exercise alone. Fourteen subjects were monitored with ECG and pulse oximetry. Brachial artery and antecubital vein catheters were placed in the nondominant (exercising) arm. Subjects breathed hypoxic gas to titrate ...

Severe-intensity constant-work-rate exercise results in the attainment of maximal oxygen uptake, but the muscle metabolic milieu at the limit of tolerance (T(lim)) for such exercise remains to be elucidated. We hypothesized that T(lim) during severe-intensity exercise would be associated with the attainment of consistently low values of intramuscular phosphocreatine ([PCr]) and pH, as determine...

High rate of muscular oxygen utilization facilitates the development of hypoxemia during exercise at altitude. Because endurance training stimulates oxygen extraction capacity, we investigated whether endurance athletes are at higher risk to developing hypoxemia and thereby acute mountain sickness symptoms during exercise at simulated high altitude. Elite athletes (ATL; n = 8) and fit controls ...

BACKGROUND Some endurance athletes exhibit exercise-induced arterial hypoxemia during high-intensity exercise. Inhalation of hyperoxic gas during exercise has been shown to counteract this exercise-associated reduction in hemoglobin oxygen saturation (SaO2), but the effects of hyperoxic gas inhalation on performance and SaO2 during high-intensity intermittent exercise remain unclear. This study...

BACKGROUND Previous studies have shown that pretreatment with normobaric hyperoxia has cardioprotective effect in isolated rat heart. The present study was designed to test the hypothesis that pretreatment normobaric hyperoxia could induce delayed cardioprotection effect in an in vivo regional heart ischemia. MATERIALS AND METHODS Experiment 1: Rats were exposed to normobaric normoxia or to n...