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Biomedical subjects

H Monod

Publications and source records attributed to H Monod.

At least 73 records · Page 4Linked to original sources
PubMed1986

Physiological modifications of local haemodynamic conditions during bilateral isometric contractions.

Nine subjects (five women and four men) simultaneously performed two isometric contractions sustained until exhaustion at different relative forces: 40% of maximum voluntary contraction (MVC) for the right elbow flexors; 50% MVC for the left elbow flexors. Contraction of the left elbow flexors commenced at 50% of the limit time (maximum maintenance time) of isometric contraction of the right elbow flexors. Increase in heart rate during concomitant contraction of the left elbow flexors led to an increase in blood flow to the right elbow flexors. Under these conditions, the limit time of isometric contraction of the right elbow flexors was prolonged with respect to the limit time obtained for an isolated isometric contraction at the same relative tension. The difference was more significant in the female (+40%, P less than 0.05) than in the male subjects (+20%, P greater than 0.05).

Adult↗
PubMed1986

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Biology↗
PubMed1985

Comparison of two modalities when exerting isometric contractions.

In order to verify whether the method employed to obtain an isometric contraction has any effects on the time for which the contraction can be sustained as well as the consequent cardiocirculatory responses, nine male subjects, from 23 to 42 years of age, carried out isometric contractions of the elbow flexor muscles against either a suspended weight (W) or a fixed strain gauge (SG). The maximum voluntary contraction (MVC) appears to be identical in both instances; and, for a given percentage of MVC, the limit-time of the isometric contraction and its accompanying heart rate changes reveal no significant differences in the two cases.

Adult↗
PubMed1985

All out anaerobic capacity tests on cycle ergometers. A comparative study on men and women.

We have studied the effects of the braking force on the results of an anaerobic capacity test derived from the Wingate test (an all out 45 s exercise on a Monark 864 cycle ergometer against a given force at the fastest velocity from the beginning to the end of the test). Seven men and seven women participated in the study and performed a total of 63 all-out tests against different braking forces. The same subjects performed a force-velocity test on the same cycle ergometer. Since the relationship between force and velocity is approximately linear for peak velocities between 100 and 200 rev X min-1 (Pérès et al. 1981a, b; Nadeau et al. 1983; Vandewalle et al. 1983) we characterized each subject by three parameters: P0 (the intercept of the force-velocity regression line with the force axis), V0 (the intercept of the regression line with the velocity axis) and Wmax (maximal power). The relationship between force and mean power was parabolic for the all-out anaerobic capacity test. In the present study the optimal force (the force giving the maximal value of mean power during an all out test) was higher for the men (approximately 1 N X kg BW-1) than the force proposed by others (0.853 N X kg BW-1 for Dotan and Bar-Or 1983). However, because of the parabolic relationship between force and mean power, the mean power which corresponds to the optimal force was approximately the same in both studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

A study of fatigue during repetitive static work performed in two different segmental positions.

Sixteen subjects, nine women and seven men, aged between 19 and 35 years, performed three series of isometric contractions of the flexor muscles of the forearm at 40% MVC. Each series consisted of four isometric contractions sustained until exhaustion, and separated from each other by an incomplete rest interval of 5 min. The position of the arm (either the lower or the upper position) was variable according to the series. Under these conditions, study of heart rate (HR), systolic blood pressure (SBP) and limit-time showed that: HR and SBP were not affected by the arm position even when fatigue was important. For a given load with a progressive appearance of fatigue, the limit-time in female subjects was higher. In both groups, in spite of the fatigue appearing after several isometric contractions performed in the upper position, movement of the arm to the lower position was sufficient to significantly increase the time-limit of another isometric contraction at 40% MVC without concomitant increase in cardiac work.

Adult↗
PubMed1983

Enzymatic adaptations to treadmill training in skeletal muscle of young and old rats.

The activities of lactic dehydrogenase (LDH), hexokinase (HK), citrate synthetase (CS), and 3-hydroacyl CoA dehydrogenase (HAD), were measured in Soleus and extensor digitorum longus (EDL) muscles of four different age groups of male Wistar rats. Young rats (3 months) and old rats (24 months) were trained during 12 weeks by a 3 days a week running exercises session. Each training session was of 2 h. All the enzymatic activities increased between 3 and 6 months in both Soleus and EDL muscles. During aging (6-27 months) Soleus showed about the same percent decrease in enzymatic activities (30%) for the four enzymes studied. In contrast with Soleus, CS activity of EDL increased with age but HK, LDH, and HAD decreased. The training induced an improvement of all enzymatic activities, except for LDH, which decreased with training in same cases. In the old group the training effect was more important than in the young group. When the relative enzymatic activities were compared it was found that Soleus muscle keeps its energy supply enzyme pattern during aging, whereas EDL evolutes to a more oxidative metabolism. Moreover old skeletal muscle remains trainable and training induces an enzymatic adaptation which follows the same pattern in both muscles: an increase of HK, CS, and HAD activities and a decrease of LDH.

Aging↗
PubMed1982

Sex differences in cardiac responses to successive apnea periods.

Cardiac response to breath-holding is generally described as a bradycardia, which is explained by a two-fold mechanism involving the pulmonary mechanoreceptors and the arterial chemoreceptors. This study was conducted to determine the cardiac effects of five successive apnea periods separated by 1 min of free ventilation (FV). Heart rate (HR) and ventilation (V, VT, f) were measured during this protocol in 12 young subjects (6 men, 6 women). Ventilatory responses during FV periods were similar in both sexes, but HR responses were different during the apnea periods. The mean exhibited a bradycardia and the women a tachycardia. Although the statistical significance of the results was weak, they showed a clear tendency which was interpreted as differences in central cardioventilatory interactions. Sex difference in the cardiac consequences of static work from respiratory muscle is also evoked.

Adult↗
PubMed1980

Sex differences in the sympatho-adrenal response to isometric exercise.

The effects on heart rate, blood pressure, and plasma catecholamines (epinephrine, norepinephrine, dopamine) of sustained isometric contraction (SIC) were studied in six women and nine men. Each subject held a tension equivalent to 30% of maximal handgrip strength until exhaustion. There were no significant differences between women and men in the duration of handgrip. Rise of heart rate and blood pressure were similar for women and men. Considering the absolute plasma levels of each catecholamine, no sex differences was observed at rest and at any time during SIC, except for epinephrine whose concentration was higher in men at first min of SIC. On the other hand, women and men exhibited different adrenergic patterns in response to SIC: in the first min of exercise the plasma level of the three catecholamines increased in men whereas for women plasma catecholamines levels were essentially unaffected. Thus, epinephrine seems to play a minor role in the regulation of heart rate and blood pressure during SIC for women. Another interesting result of our study is that SIC is able to induce an increase in dopamine plasma level for women as well as for men.

Adult↗
PubMed1979

Physiological effects of dynamic work on a bicycle ergometer combined with different types of static contraction.

The effects on heart rate, oxygen uptake, and pulmonary ventilation of muscular exercises, including both dynamic contractions, either simple or combined, were studied in 4 male subjects, aged 21 to 23 years. The dynamic work consisted in cycling on an ergometric bicycle at three power levels: 40, 80, and 100 W. The static work consisted in pushing against, pulling and holding with the arms a 6, 9, 12, or 18 kg load. The physiological effects are expressed as cardiac cost (delta HR), oxygen cost (delta VO2) and ventilation cost (delta V). The physiological cost of the combined work increases according to the cycling power and to the isometric load developed. A statistical analysis shows that the costs of combined work are not different from the sum of the costs of the static and dynamic contractions measured separately. Thus, the physiological responses to the combinations investigated are of an additive type.

Adult↗