Modelling the relationships between arterial oxygen saturation, exercise intensity and the level of aerobic performance in acute hypoxia.

Purpose: The aim of this study was to establish a model to estimate the level of arterial oxygen saturation (SpO) and help determine the appropriate hypoxic dose in humans exercising in acute hypoxia.

Methods: SpO values were collected in seven untrained (UTS) and seven endurance-trained male subjects (ETS) who performed six cycle incremental and maximal tests at sea level and at simulated altitudes of 1000, 1500, 2500, 3500 and 4500 m. Oxygen uptake was continuously measured and maximal oxygen uptake ([Formula: see text]) was determined in each subject and at each altitude.

Hypoventilation Training at Supramaximal Intensity Improves Swimming Performance.

Purpose: This study aimed to determine whether hypoventilation training at supramaximal intensity could improve swimming performance more than the same training conducted under normal breathing conditions.

Methods: For a 5-wk period, 16 triathletes (12 men and 4 women) were asked to include one supramaximal set of 12 to 20 × 25-m front crawl swimming twice a week into their usual swimming session, performed either with hypoventilation at low lung volume (VHL group) or with normal breathing (CONT group). Before (Pre) and after (Post) training, all triathletes performed all-out front crawl trials for 100, 200, and 400 m.

Periodic breathing and oxygen supplementation in Chilean miners at high altitude (4200m).

Our objective was to determine the nocturnal ventilatory pattern and characterize the effect of oxygen enrichment on nocturnal ventilatory pattern and sleep quality in miners exposed to intermittent hypobaric hypoxia at 4200m. A total of 16 acclimatized miners were studied. Nocturnal ventilatory pattern (plethysmographic inductance), arterial oxygen saturation and heart rate (pulse oximetry) were performed in 9/16 subjects.

Oxygen modulates the glutathione peroxidase activity during the L6 myoblast early differentiation process.

Aim: This work aims to study the regulation of the glutathione peroxidase and catalase activities in myoblasts from the L6 line exposed to 21%, 5% and 1% O2 during the cell differentiation.

Material And Methods: Rat L6 myoblasts were grown in 1%, 5% or 21% O2 in the presence or absence of N-acetyl cysteine. The cell proliferation was evaluated by determining the doubling time and kinetics of cultures by counting cells.

Swimmers can train in hypoxia at sea level through voluntary hypoventilation.

This study used an innovative technique of pulse oximetry to investigate whether swimmers can train under hypoxic conditions through voluntary hypoventilation (VH). Ten trained subjects performed a front crawl swimming series with normal breathing (NB), VH at high (VHhigh) and low pulmonary volume (VHlow). Arterial oxygen saturation was continuously measured via pulse oximetry (SpO2) with a waterproofed forehead sensor.

The relative contributions of anthropometric variables to vertical jumping ability and leg power in Tunisian children.

The purpose of this study was to examine the relative contributions of anthropometric variables to vertical jumping ability and leg power and to establish reference values of vertical jumping parameters in athletic Tunisian children aged 7-13 years in both sexes. Three hundred and ninety-one athletic Tunisian children (208 boys and 183 girls) aged 7-13 years were randomly selected to participate in our study. They were asked to perform squat jumps and countermovement jumps.

Effect of acetazolamide on ventilatory response in subjects with chronic mountain sickness.

Although the effects of acetazolamide (ACZ) on ventilation during acute mountain sickness are well known, there are no studies assessing its effect on ventilatory response in chronic hypoxia. We studied this effect in patients with chronic mountain sickness (CMS). Subjects with CMS, living permanently at 4300 m, were assigned in a randomized, double-blind study to 250 mg/day (n=9) or to 500 mg/day (n=9) of ACZ.

'Oxygen uptake efficiency slope' in trained and untrained subjects exposed to hypoxia.

We assessed the ability of the oxygen uptake efficiency slope, whether calculated on 100 and 80% of maximal exercise test duration (OUES(100) and OUES(80)), to identify the change in cardiorespiratory capacities in response to hypoxia in subjects with a broad range of V(O2 peak). Four maximal exercise tests were performed in trained (T) and untrained subjects (UT) in normoxia and at 1000, 2500 and 4500 m. The mean reductions in maximal exercise capacities at 4500 m were the same in T subjects for V(O2 peak) (-30%), OUES(80) (-26%) and OUES(100) (-26%) whereas in UT subjects only OUES(100) (-14%), but not OUES(80) (-20%), was lower compared with V(O2 peak) (-21%, p<0.