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Biomedical subjects

E Bouhlel

Publications and source records attributed to E Bouhlel.

7 recordsLinked to original sources
PubMed2005

Effect of combined active recovery from supramaximal exercise on blood lactate disappearance in trained and untrained man.

The purpose of this study was to determine the effect of different modalities of individualized active recovery on blood lactate disappearance after supramaximal exercise in subjects with different levels of aerobic fitness. Fourteen healthy subjects (7 trained and 7 untrained subjects mean age 20 +/- 1.5 and 19.5 +/- 1.5, respectively) participated in this study. They performed three supramaximal intermittent exercises at 60 % of the time to exhaustion at 120 % of the maximum aerobic power (MAP) with 5-min recovery periods (2 x 5 min). The third exercise was followed by 20 min of recovery. The effects of four types of recovery were compared in trained and untrained subjects: passive recovery (PR), an active recovery at an intensity corresponding to the first anaerobic ventilatory threshold minus 20 % (VT1), an active recovery at an intensity corresponding to the second anaerobic ventilatory threshold minus 20 % (VT2) and a combined active recovery (CR) which consisted of 7 min at VT2 followed by 13 min at VT1. Blood lactate levels were measured at rest and during the recovery periods. Peak blood lactate after supramaximal exercise was observed significantly earlier with VT2 and CR (4th min) than VT1 and PR (7th min) in trained and in untrained subjects. Combined active recovery (CR) showed a significantly faster lactate disappearance than did PR, VT1, or VT2 from the 7th min of recovery in trained subjects (p < 0.05) and at the 20th min in untrained subjects (p < 0.05). CR and VT2 conditions showed earlier peak blood lactate (4th min) than PR or VT1 (7th min). Blood lactate disappearance was faster in trained than untrained subjects during combined active recovery. This result suggests that the level of physical fitness plays an important role mainly in the pattern of blood lactate decrease during combined active recovery.

Adult↗
PubMed2001

Regiochemical control in intramolecular cyclization of methylene-interrupted epoxydiols.

[reaction: see text] Methylene-interrupted epoxydiols have multiple regiochemical routes for cyclization. The 5-exo process is the most prevalent under acidic conditions. However, the regioselectivity can be controlled by the appropriate choice of acid promoter and pendant groups adjacent to the epoxide. The 5-exo product is obtained exclusively without the presence of a carbocation-stabilizing pendant group. Alkenyl and thiophenyl groups adjacent to the epoxide alter the regioselectivity and enable access to the 5-endo tetrahydrofuran and 6-endo tetrahydropyran products.

Journal Article↗
PubMed1992

Respiratory, muscular, and overall perceptions of effort: the influence of hypoxia and muscle mass.

Overall, respiratory and peripheral muscular perceptions of exercise have been examined in 16 subjects (eight men and eight women), each performing four types of exercise (two-leg, one-leg, arm + shoulder, and arm ergometry) under both normoxic and hypoxic (12% oxygen) conditions. Subjects could distinguish ratings for the three types of sensation. Both overall and peripheral muscular perceptions associated with a given oxygen intake or power output increased more than respiratory perceptions as the volume of active muscle was decreased. Hypoxia tended to increase both overall and respiratory perceptions for a given absolute oxygen consumption. Cross-modal comparisons suggested an average overall RPE of close to 13 units at 70% of a task and environment-specific peak oxygen intake, irrespective of exercise conditions, but the SD of individual responses varied by at least +/- 2 units about this average. Peripheral muscular sensations dominated small muscle tasks, but the peripheral muscular RPE became relatively consistent when related to external work rate per liter of active muscle. Respiratory perceptions provided some guide to the intensity of physical activity with a given mode of exercise and fixed environmental conditions. However, if respiratory RPE is used to "fine-tune" cross-modal exercise prescriptions, account must be taken of the distorting influence of active muscle volume and of hypoxia.

Adult↗
PubMed1989

Anaerobic threshold, muscle volume and hypoxia.

Ventilatory threshold, apparent mechanical efficiency, oxygen debt repayment, heart rate and perceptions of exertion at the ventilatory threshold have been examined in 8 men and 8 women during the performance of four types of exercise (2-leg, 1-leg, arm plus shoulder, and arm ergometry) under normoxic and hypoxic (12% oxygen) conditions. The ventilatory threshold (percentage of task-specific VO2peak at which a disproportionate increase of ventilation begins) was not significantly affected by the sex of the subject, by hypoxia, or by the volume of active muscle involved in the activity, but showed poor reproducibility in small muscle tasks. The apparent mechanical efficiency in 2-leg ergometry was increased from 25.7 to 28.1% under hypoxic conditions, presumably reflecting an increased contribution of anaerobic effort to sub-maximal work. However, oxygen debt repayment following exhausting exercise was much smaller for arm than for leg ergometry. The heart rate corresponding to the ventilatory threshold decreased as the volume of active muscle was reduced. General and respiratory perceptions of effort were rather light for self regulation of an exercise prescription to the ventilatory threshold, and particularly with tasks involving the arm muscles, prescription may best be regulated by the intensity of local muscular sensations.

Adult↗
PubMed1988

Peak oxygen intake and hypoxia: influence of physical fitness.

Eight men and eight women each performed peak oxygen intake tests on a cycle ergometer breathing ambient air and a mixture of 12% oxygen in nitrogen (equivalent to an altitude of 4400 m) in the two experiments. Hypoxia induced an average 28% decrease of peak oxygen intake, with a somewhat smaller decrease of power output. There were also small decreases in peak heart rate, peak blood pressure, peak ventilation, and peak blood lactate concentration. The major part of the impairment in oxygen transport was due to a reduction of arterial oxygen saturation, with small contributions from the decrease in heart rate and the decrease of ventilation. Subjects in good physical condition suffered a larger decrement of oxygen transport than their more sedentary colleagues, probably due to an unfavorable ratio of peak diffusing capacity to peak cardiac output. However, in the short term, this handicap could be countered by hyperventilation, and such a tactic could probably improve athletic performance over moderate distances.

Adult↗
PubMed1988

Muscle mass as a factor limiting physical work.

Maximal exercise has been performed by eight men and eight women, using four types of ergometer (2-leg, 1-leg, arm + shoulder, and arm) while breathing room air and while breathing 12% O2. Results have been related to anthropometric estimates of muscle mass in the active limbs. Although significant sex differences of O2 transfer and power output are shown, the sex-specific aerobic performance was roughly proportional to active muscle volume (both when comparing individuals on a given type of ergometer and when comparing average scores of the several types of ergometer). However, the relationship was closer for steady power output than for peak O2 intake (where the scores for arm work were boosted by the use of accessory muscles and by hyperventilation). When breathing 12% O2, the 2-leg performance was substantially reduced (an average of 28.7% for O2 transport and 19.2% for power output). This effect dropped to 9.1% for O2 transport and 12% for power output in one-leg ergometry and was negligible for arm or arm plus shoulder work. It is argued that because of difficulty in perfusing small muscles, arm work is limited largely by the intrinsic power of the active muscles, that single-leg ergometry is limited rather equally by central circulatory and muscular factors, and that two-leg ergometry is almost entirely dependent on the central circulatory transport of O2.

Adult↗