Biomedical subjects

G Lac

Publications and source records attributed to G Lac.

8 recordsLinked to original sources

PubMed1996

Saliva cortisol, physical exercise and training: influences of swimming and handball on cortisol concentrations in women.

The aim of this study was to observe the influence of physical exercise and training on saliva cortisol concentrations in women. Three groups of adult women were studied: one group of sedentary controls (n = 7) and two groups of sportswomen who competed in either handball (n = 14) or swimming (n = 10) at a national level. These sportswomen gave six saliva samples during a day that included exercise which was part of their annual training programme. We noticed a significant increase in saliva cortisol concentration after exercise in the handball players (6 p.m. vs 7.30 p.m. P < 0.05) which did not appear in the swimmers or the sedentary group. There was no difference between the sedentary group and the swimmers for each sample of the day. These results showed that the type of sport played seemed to influence the concentration of saliva cortisol, the type of stress involved, the respective haemodynamic conditions of swimming and running and thermal stress also playing a part. Moreover, it seemed that the level of performance influenced the secretion of cortisol in the saliva.

Adult↗

PubMed1995

Salivary cortisol and testosterone variations during an official and a simulated weight-lifting competition.

This study was undertaken to compare salivary levels of cortisol (C), testosterone (T) and T/C ratio during an official and a simulated weight-lifting competition. Thirteen top-level weight-lifters (French team) including 7 national level athletes (NG) and 6 international level athletes (IG) entered the study. The performance levels corrected with the IWF index (an index which relates the performance to body weight) obtained during the competition were higher than those obtained during the simulation and were higher in IG than in NG. Salivary samples were collected for each session after weighing, snatch and clean-and-jerk. The mean T-levels of these athletes were the same as those obtained in the laboratory on sedentary adults; they did not vary throughout the competition, nor between the competition and the simulation. Conversely the C-levels were statistically higher in the competition than in the simulation (p < 0.05). These C-levels are correlated with the performance levels corrected with the IWF index obtained during the competition (r = 0.67; p < 0.05; n = 13). Moreover, C-levels noted at the time of the competition were higher in the international athletes than in the national ones. Therefore, we concluded that the cortisol level may be considered as a performance factor in weight-lifting.

Adult↗

PubMed1993

Analysis of performance of prepubertal swimmers assessed from anthropometric and bio-energetic characteristics.

The relationship between anthropometric and bio-energetic data and timed performance over 50 to 400 m was studied in 25 young male swimmers [11.3 (SD 1) years]. Anthropometric measurements included height, body mass, body fat mass, body area, thoracic section area (Ats) thoracic circumferences, lengths of upper limb, bi-acromial and bi-iliac diameters. Maximal oxygen consumption (VO2max; direct method), maximal anaerobic power (W(an),max; force-velocity test) and mean power in 30 s sprint (W30 s; Wingate test) were also measured. Each of these bio-energetic variables was expressed in absolute terms, relating to body mass, body area and Ats. The stepwise regression method was used to determine contribution of the variables (anthropometric and/or bio-energetic) of the time achieved over the distance. The W30 s/Ats accounted for 46% of the time over 50 m (negative correlation). The VO2max/Ats and height were negatively correlated with the times of performances over 100 m, 200 m and 400 m, these two variables accounted for 71% to 77% of the performance. These results would indicate that even in young boys, anthropometric and bio-energetic characteristics are both important in swimming performance, particularly the bio-energetic variables expressed per Ats.

Body Composition↗

PubMed1993

[Does the time change affect school children?].

The aim of the study was to determine in young pupil the physiological effect of a 1 hour earlier awakening (summer time) by measuring: the salivary cortisol level. Results showed that the cortisol circadian rhythm synchronized with summer clock time after remaining synchronized with winter time (previous rhythm) for 15 days at least.

Child↗

PubMed1984

[Spermatogenesis in the prepuberty Wistar rat during protein-energy malnutrition followed by balanced refeeding].

Protein-calorie malnutrition was induced by giving a 2% casein diet to a strain of post-weaning male Wistar rats from 26 to 56 days of age. They were then rehabilitated by a 15% casein diet till 86 days of age. Body and testis weights, diameter of seminiferous tubules and spermatogenetic score were compared to those of controls fed with the 15% casein diet. The unbalanced diet retarded growth by 30 days. Although rehabilitation of body and testis weights was incomplete, the spermatogenetic function equalled that of the controls at the end of the experiment. This aspect has been discussed.

Animals↗

PubMed1983

[Course of the levels of myofibrillar proteins in the cardiac ventricles of adult rats in protein malnutrition followed by a balanced diet].

Adult male Wistar rats weighing 320 +/- 20 g at the beginning of the experiment were divided into two equal lots. A reference lot (T) was fed on a balanced diet containing 23,5 p. 100 mixed protein, for 60 days. A deficient lot (E) was fed on a low protein diet (3 p. 100 cereal protein) for 30 days (malnutrition), then on a balanced diet for 30 days (refeeding). When the food intake was expressed in 100 g of body weight/day, both lots ate about the same amount throughout the experiment. On the contrary, the amount of N ingested/100 mg of body weight/day by the E rats was only 11 p. 100 of that of the T lot. After 30 days of refeeding, the mean weight of the E rats equalled 90 p. 100 of that of the T rats. In the E lot, during malnutrition, the nitrogen balances were always positive and their nitrogen CDU were ranged between 73-83 p. 100 in comparison with 86-88 p. 100 in the T lot. The protein concentration of cardiac ventricles was the similar in both lots of rats, during malnutrition and refeeding periods. On the contrary, the myofibrillar protein concentration was increased in the E rats during these two phases. After separation of subunits sizes of muscle proteins by sodium dodecyl sulphate gel electrophoresis, we observed that the concentrations of myosin, actin, troponin-tropomyosin complex, myosin light chains, evolved in the same way that the total myofibrillar proteins. A relative degree of cardiac myocontractile protein sparing is suggested in our chronic protein malnutrition of adult rats.

Animals↗

PubMed1982

[Course of minimal oxygen consumption in the young rat during protein energy malnutrition followed by return to a balanced diet].

Growth and resting oxygen consumption (VO2 minimal) were studied on two strains of six post-weaning male rats during 60 days. The first strain was fed with a balanced diet (15% casein) for 60 days, the second received a 2% casein diet for 30 days, and then the balanced diet for the remaining 30 days. The 2% casein diet completely stopped the body weight and VO2 minimal increases. When return to a balanced diet, these parameters show an evolution similar to that of controls of the same body weight. The VO2 minimal had the same kind of evolution as body weight and was well correlated with growth speed. The protein restriction involves a strong and temporary reduction of the VO2 minimal, which will correspond to a nutritional stress.

Animals↗

PubMedDate not supplied

Steroid assays in saliva: a method to detect plasmatic contaminations.

Plasmatic and salivary levels of six steroid hormones in adult males and females are given and compared to the data of the literature. These steroids are: cortisol (F), dehydroepiandrosterone (DHA) and its sulphate (DHAS), androstenedione (A), testosterone (T) and 11 beta OH androstenedione (OHA). The salivary assay of the last compound is an original. The correlations between salivary and plasmatic values are presented and confirm that this method is a reliable alternative for hormonal investigations. From these data and from those of the literature, the salivary versus plasmatic ratio are calculated. From the fact that high concentrations of DHAS in saliva generally stem from blood contamination, we derive a method to estimate the amount of this contamination and its impact on other steroids measured on the same saliva sample.

Adult↗