Biomedical subjects

J P Eclache

Publications and source records attributed to J P Eclache.

12 recordsLinked to original sources

PubMed1989

Decrease in respiratory quotient during exercise following L-carnitine supplementation.

This study was undertaken to determine the effects of L-carnitine addition to the diet during submaximal exercise in endurance-trained humans. Ten subjects (VO2max: 62 ml.kg-1.min-1) performed a control test (C) (45 min of cycling at 66% of VO2max) followed by 60 min of recovery in a sitting position. Each subject repeated this trial after 28 days of placebo (P) and L-carnitine (L-C) treatment (double-blinded cross-over design). The dose of each treatment was 2 g/day. There were no differences between the C and P tests. The respiratory quotient was lower (p less than 0.05) with treatment than with P or C during exercise. In addition, oxygen uptake, heart rate, blood glycerol, and resting plasma free fatty acid concentrations presented a nonsignificant trend toward higher values in L-C than in the C or P groups. These observations suggest an increased lipid utilization by muscle during exercise in the L-C-treated group. This effect has further possibilities for improving performance during submaximal exercise.

Adult↗

PubMed1981

[Plasma renin activity (PRA) and aldosterone (PA) during submaximal exercise. Effect of training (author's transl)].

The effect of training on PRA, PA, hematocrit and weight loss was studied at rest and following an exercise performed until exhaustion. Two groups of subjects were used, the first, a group of 4 young well trained men (88.6% +/- 7.7 V02 max) and the second a group of 4 young untrained men (77.5% +/- 7 V02 max). PRA and PA displayed highly significant increases after exercise in both groups, but PRA resting values were lower in the well trained subjects (p less than 0.05). PRA values were also lower in the latter group after exercise, but the difference in this case was not significant. Further, the variation of hematocrit was less (p less than 0.05) and the weight loss greater in the well trained subjects. In an additional experiment, the same parameters were studied in four subjects submitted to a five month training programme (87% V02 max). Though resting values for PA remained unchanged after training, PRA resting values and PRA post exercise values were significantly lower. A comparison between the magnitude of weight loss and hematocrit variation showed that when untrained subjects became trained, the variation of hematocrit was smaller (p less than 0.05) while weight loss was larger (p less than 0.01). These observations could be explained in terms of the change in blood volume, and/or a decrease in sympathetic nervous activity induced by training.

Adult↗

PubMed1980

Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men.

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.

Adult↗

PubMed1979

[Chemoreflexive drive of ventilation and noradrenaline stimulus in man].

O2 chemoreflex drive of ventilation was studied before and after an intravenous infusion of L-norepinephrine (9 microgram/min), inducing a plasmatic hormone concentration similar to that obtained during submaximal exercise. The ventilation increasing rapidly at the beginning of the infusion was stabilized after 30 min : the ventilation was two times the reference value. The O2 chemoreflex drive of ventilation increased during norepinephrine infusion. When man was transiently switched from hypoxia to pure O2 (O2 test) the maximal fall of ventilation was two times the reference response. This increase in the chemoreflex drive, although the physico-chemical blood state was unchanged, may be explained by a norepinephrine chemoreceptor sensitization. Such a mechanism could partly explain the increase of O2 chemoreflex drive observed during muscular exercise.

Adult↗

PubMed1979

Self-pacing during sustained, repetitive exercise.

During Exercise Fastball, 25 young French infantry soldiers walked 204 km in 6 d. A different load weight was assigned to each subject to ensure that they all worked at the same percentage of their aerobic power (Vo2max). The actual energy expended during the march was monitored by recording heart rates by ECG telemetry. The results confirmed that adjusting the load weight is a practical means of ensuring the same relative workload for subjects with different Vo2max. Furthermore, fit young soldiers will self-pace at 30-40% of Vo2max and will continue to do so for at least 6 d. The factor limiting performance for many of these subjects was the condition of their feet as a result of walking on the hard road surface.

Energy Metabolism↗

PubMed1974