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Biomedical subjects

G Camus

Publications and source records attributed to G Camus.

At least 37 records · Page 2Linked to original sources
PubMed1990

Tocopherol mobilization during dynamic exercise after beta-adrenergic blockade.

This study addresses the question of whether tocopherol mobilization during exercise could be explained by a lipolysis effect. Nine healthy male subjects were submitted to dynamic exercise of graded intensity (45, 60, 75% VO2max) on a cycle ergometer after ingestion of either a placebo or 40 mg propranolol as beta-blocker. Plasma tocopherol concentration increased toward a peak value reached during or at the end of exercise. The magnitude of this increase did not differ in the two experimental conditions while plasma free fatty acids concentration was lowered under beta-adrenergic blockade by propranolol. From these results, we conclude that tocopherol mobilization during dynamic exercise does not depend on lipolysis.

Adult↗
PubMed1988

Slow upward drift of VO2 during constant-load cycling in untrained subjects.

The oxygen uptake kinetics during constant-load exercise when sitting on a bicycle ergometer were determined in 7 untrained subjects by measuring breath-by-breath VO2 during continuous exercise to volitional exhaustion (mean endurance time = 1160 +/- 172 s) at a pedal frequency of 70 revolutions.min-1. The power output, averaging 189.5 W, was set at 82.5% of that eliciting the individual VO2max during a 5 min incremental exercise test. Throughout the exercise period, the VO2 kinetics could be appropriately described by a two-component exponential equation of the form: VO2(t) = Ya[1 - exp(-kat)] + Yb[1 - exp(-kbt)] where VO2 is net oxygen consumption and t the time from work onset. VO2 measured at the end of exercise was close to VO2max (98% VO2max) and the mean values of Ya, ka, Yb and kb amounted to 1195 ml O2.min-1, 0.034 s-1, 1562 ml O2.min-1, and 0.005 s-1 respectively. The initial rate of increase in VO2 predicted from the above equation is slower than that calculated, for the same work intensity, on the basis of the data obtained by Morton (1985) in trained subjects. For t greater than 480 s, however, the two models yield substantially equal results.

Bicycling↗
PubMed1988

Tocopherol mobilization during intensive exercise.

This work shows that the level of plasma tocopherol (vitamin E) which has free radical scavenging properties rises significantly during intensive exercise. It is proposed that mobilization of tocopherol could help to prevent lipoperoxidation phenomena occurring in exercising skeletal muscle. A hypothetical mechanism relating to a lipolysis effect is discussed to explain this mobilization.

Adult↗
PubMed1988

[Relation between endurance time and maximal oxygen consumption during supramaximal running].

The relationship between speed and the maximal length of time supramaximal runs can be sustained (temps-limite, tlim) has been studied in seven male subjects (physical education students). Within the range of intensity studied, tlim strictly depends on maximal oxygen consumption (VO2max). The relationship between tlim and the relative energy cost of the exercises per unit of time (E), calculated by subtracting the maximal power of aerobic metabolism (Emaxox) from E, removes the interindividual differences of tlim. The function tlim = f(E-Emaxox) is described by an empirical equation of the form: tlim = a.exp[-b(E-Emaxox)] (r = 0.979; P less than 0.001), where the parameters a and b are respectively equal to 330.8 and 0.14 and where tlim, E and Emaxox are respectively expressed in seconds and in watts per kg of body weight.

Adult↗
PubMed1985

[Kinetics of oxygen consumption during running of supramaximal intensity in differently trained subjects].

The rate of increase of the oxygen consumption (VO2) at the onset of supramaximal exercise has been compared in trained and untrained subjects. The velocity constant of the VO2 increase up to its maximum (VO2 max) is proportional to the energy requirements of the exercise (WO2). For a given (WO2-VO2 max) value, the kinetics of VO2 is roughly the same in both types of subjects. In both cases, VO2 reaches on an average WO2 divided by 2 after 29 seconds whatever the WO2 level. The corresponding velocity constant is 1.4 min-1.

Adult↗
PubMed1985

[Calculation of record-time in the 800-meter run: predictive value of Margaria's equation].

Margaria's equation (1976)--describing the relationship between the minimum time necessary to cover a distance equal or longer than 1,000 m (record-time TR) and the maximal oxygen consumption (VO2 max)--has been modified in order to be applied to the calculation of TR in the 800 m foot race. Fifteen subjects participated in this study (VO2 max = 63 +/- 3.5 ml O2 X kg-1 X min-1, measured TR = 131 +/- 10 seconds). It has been found the TR calculated from Margaria's equation (TRc) are underestimated (TRc = 104 +/- 10 seconds). By taking into account the actual energy cost of running (0.19 ml O2 X kg-1 X m-1) and the kinetics of VO2 at the onset of exercise, TRc averaged 133 +/- 8.5 seconds. Moreover, the relationship between TRc and measured TR (TRm) is highly significant (TRc = 50.4 + 0.65 TRm; r = 0.75; P less than 0.01). These results validate Margaria's equation modifications.

Adult↗
PubMed1985

[Relation between maximal oxygen consumption and the record time in the 1500-meter run. Analysis of Lloyd's model].

Lloyd's equation (Lloyd, 1967 b) has been applied to the calculation of record time in the 1 500 meters foot race from VO2 max. Twenty-eight healthy male subjects participated in this investigation. Record times decrease with increasing VO2 max. The theoretical curve plotted from Lloyd's equation is consistent with this trend. Moreover, the relationship between calculated record times (TRc) and measured record times (TRm) is highly significant (TRc = 74.3 + 0.7 TRm; r = 0.883; P less than 0.001). These results validate Lloyd's equation and hypothesis.

Humans↗
PubMed1984

[Energetic equivalent of the production of plasma lactate during running of supramaximal intensity].

The energy equivalent of plasma lactate production (ELAp) represents the amount of energy that can be derived from the anaerobic glycolysis per kg body weight when the peak plasma lactate concentration (LAp) after exercise increases by 1 mM. ELAp has been calculated from the relationship between the oxygen deficit (Do2) and LAp in 32 subjects. LAp and oxygen uptake measurements were made during constant speed supramaximal running until exhaustion or during the course of constant-speed supramaximal runs of different duration interrupted by 8- to 10- min resting periods. The relationship between Do2 and LAp is described by a linear equation where the slope is equal to ELAp. This equation is: Do2 = 12.3 + 2.4 LAp (r = 0.958; P less than 0.001), where Do2 is expressed in ml O2/kg and LAp in mmol/litre (mM). These findings validate LAp measurements as an index of the anaerobic metabolism during supramaximal running.

Adult↗
PubMed1982

[Tachycardia induced by a hot bath].

When immersed in plain water at 40 degrees C, normal young adults experience an important increase in the heart rate. beta adrenergic receptor blockade by propranolol (40 and 80 mg) reduces this tachycardia by 25%. The increase in the heart rate depends on orthosympathetic stimulation, on parasympathetic inhibition and on a Q10 effect related to the blood temperature acting on the sino-auricular node.

Adult↗
PubMed1982

[Cardiovascular changes induced by isometric exercise in aged subjects].

Blood pressure and heart rate during static contraction of forearm muscles holding a tension of 30% maximal voluntary strength for 5 mn have been measured. Eleven young men and 11 elderly male subjects were used. Maximal voluntary strength is reduced by 19% in elderly subjects. Relative mean cardio-vascular responses were unaffected by age.

Adult↗
PubMed1982

[Changes in plasma volume in submaximal exertion of short duration].

Changes in plasma fluid volume and hyperlactacidemia were measured in nine healthy young men who had been running 10 min on a motor-driven treadmill (work rate from 40 to 90% V0, max). Our results show that there is a linear relationship between reduction of plasma fluid volume and intensity from 50% of max. For a given intensity the reduction of plasma fluid volume is a function of hyperlactacidemia.

Humans↗
PubMed1980

[Endurance after propranolol in the human execution of a general dynamic exercise].

The effects of a single oral dose of 40 mg propranolol on endurance time and on the maximum oxygen consumption were studied in eight healthy young men. They were running on a motor-driven treadmill (work rate from 80 to 150% VO2 max. The VO2 max and endurance time were decreased to an average of 10 and 30% of controls respectively. The relationship between the endurance time and the relative work load (VO2/VO2 max) remained unchanged after beta-adrenoceptor blockade. The reduction of the endurance time following beta-adrenoceptor blockade is a consequence of the reduction of the VO2 max.

Adult↗