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OBJECTIVES Heart-rate variability (HRV) is an interesting tool for assessing cardiac autonomic system control, but nonstationarities raise problematic issues. The objective of this paper is to show that adapted signal processing tools may cope with nonstationary situations and improve the analysis of HRV. METHODS We propose to use the recent method of(More)
Heart beat rate and blood pressure, together with baroreflex sensitivity, have become important tools in assessing cardiac autonomic system control and in studying sympathovagal balance. These analyses are usually performed thanks to spectral indices computed from standard spectral analysis techniques. However, standard spectral analysis and its(More)
Orthostatic intolerance (OI) is the most serious symptom of cardiovascular deconditioning induced by head-down bed rest or weightlessness. Wearing venoconstrictive thigh cuffs is an empirical countermeasure used by Russian cosmonauts to limit the shift of fluid from the lower part of the body to the cardio-cephalic region. Our aim was to determine whether(More)
The purpose of this study was to compare the effects of spontaneous recovery or recovery by treadmill training (180 min/day, 5 days/wk, 30 m/min for 8 wk) on maximal O2 uptake (VO2max), histochemical and biochemical muscular properties (soleus), of rats subsequent to 5 wk of hindlimb suspension. Spontaneous recovery reversed the 15% reduction in VO2max,(More)
Techniques for examining signals in the time and frequency domains are well-established tools. These tools have their limitations; they tell us in a broad sense where the signal component exists in the frequency domain, but they do not tell us how its frequency characteristics change over time. The time-frequency has become a powerful alternative for the(More)
The aim of this study was to investigate the possible relation between the modifications in locomotor activity (on running wheel) which occur during prolonged fasting and changes in the utilization of energy reserves. In 18-week-old rats, we found that the rate of body mass loss reflects the changes in nitrogen excretion that occur over three phases of(More)
Exposure to microgravity in humans causes cardiovascular deconditioning affecting blood pressure, heart rate and vascular responsiveness. This study investigated cardiac output, arterial blood pressure and regional blood flows [radioactive microspheres: 57Co, 15.5 (SEM 0.1) μm in diameter] in conscious and freely moving rats subjected to 14 days of(More)
OBJECTIVE To compare the tocolytic potency of ritodrine, nicardipine and atosiban, used alone and in dual combinations, to see whether combinations of these drugs, which act via different pathways, could improve inhibition of uterine contractility. DESIGN Study on myometrial contractility in vitro. SETTING Laboratory of physiology, Lyon, France. (More)
We hypothesized that spontaneous movements (postural adjustments and ideomotion) disturb analysis of heart rate and blood pressure variability and could explain the discrepancy between studies. We measured R-R intervals and systolic blood pressure in nine healthy sitting subjects during three protocols: 1) no movement allowed, 2) movements allowed but not(More)