Visual and brainstem auditory evoked potentials and maximal aerobic exercise: does the influence of exercise persist after body temperature recovery?

Transversal studies have shown a strong correlation between specific evoked potential (EP) values and specific physical activities, as well as between EP values and the amount of training. Prior to longitudinal studies investigating the effect of training in EPs, it is mandatory to determine whether a recent training session could interfere with regular EP recording. Exercise-induced hyperthermia is known to modify EP values. The purpose of the study was to determine whether an acute exercise can induce EP modification persisting after body temperature recovery. We measured two sets of visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) in 16 males (8 cyclists and 8 sedentary peers), one before and the other after a maximal cycloergometric graded exercise test. The second test was performed immediately after body temperature recovery. We chose to test cyclists, as their specific training corresponded to the exercise test we performed on a cycloergometer. The repeated measures before and after the exercise test showed no significant differences, neither in VEPs nor in BAEPs, for any subject of the study. Recording VEPs and BAEPs in cyclists, we observed no difference related to this particular sport training. This study showed that VEP and BAEP values were similar to those measured before a maximal exercise when body temperature returned to pre-exercise value. This original work demonstrated that VEP and BAEP recordings can be reliably performed after a recent training session, provided body temperature has returned to basal level.

Decreased pulmonary diffusing capacity of divers over a 6-year period.

Non-smoking, male, professional firemen divers (n = 15) underwent two pulmonary function tests (PFT) separated by 6 years. Measured data were compared to European Coal Steel Community recommended reference values to permit cross-sectional and then longitudinal study. Higher vital capacity (VC; P < 0.01) and forced expiratory volume in 1 s (FEV1; P < 0.05), and lower maximal mid-expiratory flow (MMEF) coefficient with VC (MMEF/VC; P < 0.05) were observed in both PFT. Diver's pulmonary diffusing capacity (DL(CO)) and the coefficient with alveolar volume (DL(CO)/V(A)) showed significantly (P < 0.001) different evolution profiles than those expected from predicted values. In divers, DL(CO) and DL(CO)/V(A) decreased from 104.0% to 91.4% and from 106.4% to 91.5% of predicted values respectively. Changes in DL(CO) and DL(CO)/V(A) correlated positively with the initial measurement of DL(CO) (r = 0.67, P < 0.01) and DL(CO)/V(A) (r = 0.74, P < 0.01) respectively, whereas no correlation between changes in pulmonary gas transfer function and age or diving history parameters was found. Thus, it is suggested from our observations that hyperbaric atmosphere exposure increases the effects of aging on pulmonary diffusing capacity and that pulmonary gas transfer function should be regularly tested in professional and recreational divers.

Short-term effect of cold provocation on single-breath carbon monoxide diffusing capacity in subjects with and without Raynaud's phenomenon.

The lung diffusing capacity for carbon monoxide was determined by the single breath method (DLCOsb) before, during, and after immersion of the left hand in cold water in four groups of subjects: (i) normal individuals; (ii) subjects with idiopathic Raynaud's disease; (iii) patients with progressive systemic sclerosis without associated Raynaud's phenomenon; and (iv) patients with connective tissue disease associated with Raynaud's phenomenon. Our results showed significant differences in the evolution of DLCOsb after cold stimulation between the groups. Control subjects (group one) showed a transient but significant reduction in DLCOsb at the end of two minutes of cold stimulation, normalizing ten minutes later. Subjects with primary Raynaud's phenomenon (group two) showed on the contrary a transient but significant rise in DLCOsb after 2 minutes, while subjects with an isolated connective tissue disease without Raynaud's phenomenon (group three) showed a significant decrease in DLCOsb at both observation times. Patients with Raynaud's phenomenon associated with a connective tissue disease (group four) showed a delayed decrease in DLCOsb ten minutes after cold stimulation. This latter result appeared as an addition to the effects of cold stimulation observed in groups two and three.

Pulmonary function of a firemen-diver population: a longitudinal study.

Non smoking, male professional firemen-divers (n = 20) underwent two pulmonary function tests (PFT) separated by 8-9 years. Measured data were compared to European Coal Steel Community recommended reference values to permit cross-sectional and then longitudinal studies. Higher vital capacity (VC) and forced expiratory volume in 1 s (FEV1; both P < 0.001), and lower residual volume (P < 0.01) were observed in both PFT. Longitudinal analysis showed a smaller VC reduction than FEV1 reduction, leading to a FEV1/VC percentage decrease with time. Maximal mid expiratory flow (MMEF) and MMEF/VC changes during this 9-year period showed an unusually pronounced decrease, suggesting possible chronic effects of diving on small airways. Thus, it is suggested from our observations that a hyperbaric stimulus compensates in part for the effects of aging on VC and that obstructive disease could occur in subjects with long diving experience.

Visual evoked potentials: differences related to physical activity.

Visually evoked potentials to patterned stimuli were recorded from tennis players, rowers and non-athlete control subjects. Each group consisted of 12 males and 12 females of similar age. Tennis players showed shorter P100 latencies compared to those of control subjects and rowers. This difference exists, in the same range, both in the male and in the females. The analysis of covariance and multiple linear regressions show that these shorter latencies cannot be explained by head circumference or by height. The hypothesis of a relationship between these shorter latencies and the specific qualities of racket players is suggested. A second experiment with squash players seems to confirm these first results.

[EEG recorded after effort in triathletes. Influence of prior inhalation of hyperbaric oxygen]. / EEG quantifié après effort chez le triathlonien. Influence de l'inhalation préalable d'oxygène hyperbare.

Quantitative EEG was recorded during 3 sessions, once a week, in 10 high-level amateur triathletes, who regularly competed in triathlon. At each session, the EEG was recorded 15 min after a submaximal exercise test. During the second session, the exercise test came immediately after 30 min of hyperbaric oxygenation (100% oxygen at 2 atmosphere absolute pressure). The others conditions of the EEG recording were the same for the 3 sessions. The purpose of the work was to study the variations of the EEG power spectrum (from 1 to 20 Hz) which occurred between the 3 sessions. Descriptive analysis of the results show, after hyperbaric oxygenation, a diffuse increase of absolute power for several frequencies in the theta, alpha and beta bands.

[Cardiac adaptation in highly skilled swimmers and soccer player: a vectorcardiographic approach]. / Adaptation cardiaque chez des nageurs et des footballeurs de haut niveau : approche vectorcardiographique.

Nine swimmers and nine soccers have been studied by the mean of Frank lead vectorcardiographic system. According to classical criteria, both the two groups present similar marked left ventricular hypertrophy. Numerous indices suggest that right ventricular hypertrophy is also associated though more important for the swimmers. The assumption of volume overload because of special hemodynamic conditions during swimming is proposed.

[Cardiovascular effects of S 2620 in dogs anesthetized with pentobarbital]. / Propriétés cardio-vasculaires du S 2620 chez le chien anesthésié au pentobarbital.

In the dog under pentobarbitone anesthesia, the intravenous infusion of 1 mg/kg S 2620 results in tachycardia and systemic arterial hypertension. The same attenuated effects are caused by a second injection of the drug after cervical vagotomy and chemoreceptors denervation. Tachycardia and peripheral vaso constriction can account for elevation of arterial pressure.

Influences de la castration et du propionate de testosterone sur le comportement des rats conditionnes par paires.

Four groups of 10 male rats (Group A: normal rats, Group B: castrated rats, Group C: castrated rats + 1 mg P.T./day, Group D: castrated rats + 1 dose of 50 mg/kg of P.T. cyclohexane) were avoidance conditioned during nine sessions of 50 trials. They were conditioned individually during sessions 4, 5 and 6 and by pairs during sessions 1, 2, 3, 7, 8 and 9. During these last sessions, all groups presented a low level of acquisition and aggressive behaviour. These phenomena were worsened in the castrated rats whose performances stayed low even when they were conditioned individually. On the other hand, the frequency of their aggressive behaviour was often higher than that of the other groups. The injection of P.T. cyclo-hexane improves the performance of the castrated animals but does not entirely compensate for the differences between control and experimental rats.

[Synchronous electric activity with inspiration in the vastus lateralis muscle of the anesthesied dog breathing spontaneously]. / Activité électrique synchrone avec l'inspiration dans le muscle vaste externe du Chien anesthésié respirant spontanément

In the dog, under chloralose or pentobarbitone anesthesia and breathing spontaneously, a muscular electrical activity of low voltage synchronous with respiration was observed in m. vastus lateralis. The mean maximum amplitude of this activity is inversely linked with respiratory rate. When the respiratory frequency is equal or exceeds 25 cycles per minute this activity disappears. Such a phenomenon seems to be related to the activity of the respiratory centre.

[Respiratory stimulant effect of S 2620 in the dog anesthetized with pentobarbital]. / Action stimulante respiratoire du S 2620 chez le chien anesthésié au pentobarbital

In the dog under pentobarbitone anesthesia, the intravenous injection of 1 mg/kg S 2620 is followed by a significant increase in respiratory rate, PaO2 and pHa and by a large decrease in PaCO2. Cervical vagotomy and chemoreceptor denervation reduced and even abolished these effects. They can be induced again by a second intravenous injection or by direct instillation in the fourth ventricle. These results suggest a central action of the drug.

[Rhythmic patterns of food and water intake in the dog: preliminary study (author's transl)]. / Rythmes spontanés des prises alimentaire et hydrique chez le chien: etude préliminaire

The spontaneous rhythmic patterns of food and water intake in the dog during periods of 24 hr have been studied under three experimental conditions: natural light, continuous light and artificial light with day and night sequences. Under natural light there is a rhythmic pattern in the frequency of food intake and the amount of food consumed. During the night, periods of food consumption are numerous and the amount of food ingested is significant. During the day both the number of periods of food intake and the amount of food consumed is less. Similar results were obtained under continuous light. Under artificial light, with day and night sequences, there is a tendency to equalize the amount of food consumed through the 24 hr. This produced a displacement of frequency curves. In these three situations there seems to be an important relationship between the amount of food consumed and the time intervals following periods of food intake. Generally, similar results were obtained for water intake.