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PURPOSE We hypothesized that the third dynamic phase (ϕ3) of the cardiovascular response to apnoea requires attainment of the physiological breaking point, so that the duration of the second steady phase (ϕ2) of the classical cardiovascular response to apnoea, though appearing in both air and oxygen, is longer in oxygen. METHODS Nineteen divers performed(More)
Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the(More)
The purpose of the present study was to assess the reliability of metabolic parameters measured using (31)P magnetic resonance spectroscopy ((31)P MRS) during two standardized rest-exercise-recovery protocols. Twelve healthy subjects performed the standardized protocols at two different intensities; i.e., a moderate intensity (MOD) repeated over a two-month(More)
We tested the hypothesis that, after bed rest, maximal oxygen consumption ( VO₂max ) decreases more upright than supine, because of adequate cardiovascular response supine, but not upright. On 9 subjects, we determined VO₂max and maximal cardiac output (Q ) upright and supine, before and after (reambulation day upright, the following day supine) 35-day bed(More)
The aim of this study was to investigate whether (1) spinal modulation would change after non-exhausting eccentric exercise of the plantar flexor muscles that produced muscle soreness and (2) central modulation of the motor command would be linked to the development of muscle soreness. Ten healthy subjects volunteered to perform a single bout of backward(More)
BACKGROUND Cardiac output (CO) is a major diagnostic and prognostic factor in pre-capillary pulmonary hypertension (PH). Reference methods for CO determination, like thermodilution (TD), require invasive procedures and allow only steady-state measurements. The Modelflow (MF) method is an appealing technique for this purpose as it allows non-invasive and(More)
Interpolation methods circumvent poor time resolution of breath-by-breath oxygen uptake ( $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 ) kinetics at exercise onset. We report an interpolation-free approach to the improvement of poor time resolution in the analysis of $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 kinetics. Noiseless and noisy (10 % Gaussian noise) synthetic data(More)
We hypothesised that phase II time constant (τ2) of alveolar O2 uptake ( [Formula: see text] ) is longer in hypoxia than in normoxia as a consequence of a parallel deceleration of the kinetics of O2 delivery ( [Formula: see text] ). To test this hypothesis, breath-by-breath [Formula: see text] and beat-by-beat [Formula: see text] were measured in eight male(More)
This study investigated the effects of acute hypoxia on spinal reflexes and soleus muscle function after a sustained contraction of the plantar flexors at 40 % of maximal voluntary isometric contraction (MVC). Fifteen males (age 25.3 ± 0.9 year) performed the fatigue task at two different inspired O2 fractions (FiO2 = 0.21/0.11) in a randomized and(More)