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Biomedical subjects

M Bedu

Publications and source records attributed to M Bedu.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effect of chronic hypoxia and socioeconomic status on VO2max and anaerobic power of Bolivian boys.

The aim of this work was to analyze the effects of altitude and socioeconomic and nutritional status on maximal oxygen uptake (VO2max) and anaerobic power (P) in 11-yr-old Bolivian boys. At both high (HA) (3,600 m) and low (LA) (420 m) altitudes, the boys were divided into high (HA1, n = 23, LA1, n = 48) and low (HA2, n = 44, LA2, n = 30) socioeconomic levels. Anthropometric characteristics, VO2max, and P [maximal P (Pmax) during a force-velocity test and mean P (P) during a 30-s Wingate test] were measured. Results showed that 1) anthropometric parameters were not different between HA1 and LA1 and HA2 and LA2 boys, but HA2 and LA2 boys were two years behind HA1 and LA1 boys in development; 2) VO2max was not different in boys from the same altitude, but at HA VO2max was 10% lower than at LA (HA1 = 37.2 +/- 5.6, HA2 = 38.9 +/- 6.4, LA1 = 42.5 +/- 5.8, LA2 = 42.5 +/- 5.3 ml.min-1 x kg-1 body wt); and 3) Pmax and P were higher in well-nourished than in undernourished boys, but there was no difference in Pmax and P between HA1 and LA1 and HA2 and LA2 boys (HA1 = 6.8 +/- 1.0, HA2 = 5.5 +/- 0.8, LA1 = 7.1 +/- 1.0, LA2 = 5.3 +/- 0.9 W/kg for Pmax; HA1 = 5.2 +/- 0.8, HA2 = 4.5 +/- 0.9, LA1 = 5.2 +/- 0.7, LA2 = 4.0 +/- 0.6 W/kg for P).(ABSTRACT TRUNCATED AT 250 WORDS)

Altitude↗
PubMed1993

Chemical and nonchemical stimuli during breath holding in divers are not independent.

In the breath-hold model described by S. Godfrey and E. J. M. Campbell (Respir. Physiol. 5: 385-400, 1968), chemical and nonchemical stimuli are independent. Because these two factors are time dependent, the effect of each could not be measured by breath-holding time (BHT). The aim of this study is to dissociate chemical and nonchemical stimuli and to assess the effects of BHT and PCO2 on respiratory center output by measurement of occlusion pressure (P0.1) and mean inspiratory flow (VI). Nine well-trained divers (age 36.5 +/- 5.0 yr) took part in the study. Each subject had to hold his breath at 75% of vital capacity for 30, 50, and 70 s of BHT. Before each breath hold, the subject inspired successively two vital capacities of the same CO2-O2 gas mixture. P0.1 and VI were measured during the first reinspiration after the breath hold. For the same BHT, we observed good linear relationships between P0.1 or VI and alveolar PCO2. The slopes of these relationships increased with BHT. For alveolar PCO2 of > 50 Torr, P0.1 increased linearly with BHT. These results indicate that, during breath holding, chemical and nonchemical stimuli acted linearly on respiratory motoneuron activity, but they were not independent.

Adult↗
PubMed1992

Inter-relationships between pituitary-adrenal hormones and catecholamines during a 6-day Nordic ski race.

The aim of the study was to investigate the inter-relationships between pituitary-adrenal hormones and catecholamines during a prolonged competition over 6 days. Plasma adrenocorticotropic hormone (ACTH), cortisol (C), beta-endorphin (beta EP), free and sulphated adrenaline (A) and noradrenaline (NA) were measured in 11 volunteer male subjects during a national Nordic-ski race (323 km). Blood samples were obtained before the competition in the evening as control (D0), and before and after each day's racing (D1-D6). The mean daily heart rate (fc) was calculated from fc values recorded every minute during the race. The results showed the following: changes in mean fc [from 147 (SEM 3) to 156 (SEM 3) beats.min-1 according to the day] were not significant during the race. Diurnal variations in ACTH, beta EP and C were no longer apparent after the race: evening levels were higher than their respective D0 values during the race, except on D3 when there was a lack of response to exercise in the three hormones. Unlike ACTH and beta EP, pre- and postexercise C values on D1 and D2 were higher than those on the subsequent days (P less than 0.001). In contrast, there was a progressive accumulation of A and NA in pre- and postrace concentrations which reached a plateau in about 4 days. Positive correlations between exercise responses in ACTH, C and beta EP were found especially on D3 and D6 (P less than 0.001) but there were no significant correlations between catecholamines and the other three hormones. Thus, prolonged competition over 6 days evoked different control mechanisms for hormones of the pituitary-adrenal axis and catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1992

A simple calibration method for mechanically braked cycle ergometers.

The calibration of cycle ergometers should be checked regularly. Some studies have shown calibration errors of more than 40%. A simple, inexpensive calibrating method for mechanically braked cycle ergometers was developed and tried out on a new type of ergocycle. The cycle ergometer was elevated and the crank replaced by a pulley fitted to the shaft. The crank speed (rpm) increased linearly as a function of time when different masses were applied on the pulley. For a given braking force on the cycle ergometer, different accelerations corresponding to the increased pulley forces could be measured. When extrapolating for zero acceleration, it was possible to determine a "limit-force" which allowed the system to be in equilibrium. Additional force creates motion. The same experiments were repeated with increasing braking forces. Using the differently sized gear sprockets of the transmission system, it was possible to calculate the actual force, including all the resistances. The actual force found by the calibrating method was then compared with the indicated force proposed by the manufacturer. With increasing forces, the relative errors decreased from 9.6 to 2.9%. The cycle ergometer calibrated by this technique meets the standards recommended in exercise physiology.

Calibration↗
PubMed1992

Bioenergetic characteristics of swimmers determined during an arm-ergometer test and during swimming.

The maximal oxygen uptake (VO2max) of 13 swimmers was determined by an arm-ergometer test (direct method) and estimated from a maximal multistage swimming test (indirect method) (23). A test-retest of the progressive swimming exercise showed that there were no significant differences from one test to the other and that there were significant correlations between the principal parameters: arm stroke index: 0.73, maximal aerobic swimming velocity: 0.94, VO2max: 0.95, p less than 0.01. Therefore, for swimmers of average ability, the reproducibility of this test has been proved. A significant difference (p less than 0.001) was observed between the two tests for VO2max: arm-ergometer test (VO2max arms): 2.4 +/- 0.5 l.min-1, swimming test (VO2max ST): 3.2 +/- 0.7 l.min-1, p less than 0.01. This difference appeared to be linked to the use of a greater muscle mass (arms and legs) during swimming. A significant correlation (r = 0.73, p less than 0.01) was obtained between VO2max (l.min-1) by using both the direct and indirect exercises as methods of measurement. However, the level of r did not permit the prediction of one parameter from the other. Significant correlations were obtained between VO2max and performances over 200 and 400 m free style regardless of the methodology used (VO2max arm, VO2max ST). Moreover, only VO2max (arm, ST) emerged as a variable accounting for swimming performance from a step-wise multiple regression analysis, in which biometric and bioenergetic parameters were taken into account.

Adolescent↗
PubMed1992

Physical fitness of children resident at high altitude in Bolivia.

In 7-15-yr-old children living in La Paz (Bolivia, altitude 3,700 m) (HA): 1) Maximal oxygen consumption (VO2max) varies from 35 to 45 ml.min-1.kg-1 and maximal heart rate from 188 to 194 beats.min-1. These values are lower than those of their counterparts at low altitude (LA) by 10-20% and 10-15 b.min-1, respectively. 2) The anaerobic metabolism is not affected by chronic hypoxia if the nutritional conditions and pubertal development of HA and LA boys are the same. When related to percent of VO2max, submaximal O2 debts are similar at HA and LA. After supramaximal exercise, maximal O2 debts (45.7 +/- 2.7 vs 45.9 +/- 3.8 ml.kg-1) and blood lactate concentrations (7.6 +/- 0.6 vs 6.5 +/- 0.6 mmol.l-1) are also the same at HA and LA. No differences are observed between the 2 altitudes in ventilatory (60 vs 56% VO2max) and lactate (60 vs 65% VO2max) thresholds. The altitude of La Paz does not alter the anaerobic performance of a force-velocity test (from 6 to 10 W.kg-1) between the ages of 7 to 15 years but reduces by 14-17% the mean anaerobic power developed during a 30-s Wingate test. This decrease could be linked to a lower participation of glycolysis and aerobic metabolism at HA during this test. 3) Poor socio-economic and nutritional conditions do not modify the aerobic performance of boys living in La Paz but lead to lower maximal anaerobic power (from -17% to -25%) when compared with HA boys from a high socio-economic background.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Bio-energetic profile in 144 boys aged from 6 to 15 years with special reference to sexual maturation.

The effects of growth and pubertal development on bio-energetic characteristics were studied in boys aged 6-15 years (n = 144; transverse study). Maximal oxygen consumption (VO2max, direct method), mechanical power at VO2max (PVO2max), maximal anaerobic power (Pmax; force-velocity test), mean power in 30-s sprint (P30s; Wingate test) were evaluated and the ratios between Pmax, P30s and PVO2max were calculated. Sexual maturation was determined using salivary testosterone as an objective indicator. Normalized for body mass VO2max remained constant from 6 to 15 years (49 ml.min-1.kg-1, SD 6), whilst Pmax and P30s increased from 6-8 to 14-15 years, from 6.2 W.kg-1, SD 1.1 to 10.8 W.kg-1, SD 1.4 and from 4.7 W.kg-1, SD 1.0 to 7.6 W.kg-1, SD 1.0, respectively, (P less than 0.001). The ratio Pmax:PVO2max was 1.7 SD 3.0 at 6-8 years and reached 2.8 SD 0.5 at 14-15 years and the ratio P30s:PVO2max changed similarly from 1.3 SD 0.3 to 1.9 SD 0.3. In contrast, the ratio Pmax:P30s remained unchanged (1.4 SD 0.2). Significant relationships (P less than 0.001) were observed between Pmax (W.kg-1), P30s (W.kg-1), blood lactate concentrations after the Wingate test, and age, height, mass and salivary testosterone concentration. This indicates that growth and maturation have together an important role in the development of anaerobic metabolism.

Adolescent↗
PubMed1991

Force-velocity and 30-s Wingate tests in boys at high and low altitudes.

The effects of high altitude (HA, 3,700 m) on performance during a force-velocity test (maximal anaerobic power, MAnP) and a 30-s Wingate test (mean power, P) were studied in boys 7-15 yr of age. Forty-seven children acclimatized to HA were compared with 101 living at low altitude (LA, 330 m). They had the same good nutritional status and the same level of physical activities [average 5.4 +/- 1.1 (SD) and 5.2 +/- 1.9 h/wk at HA and LA, respectively]. They performed the two tests using the same calibrated cycle ergometer. For the Wingate test, O2 uptake (VO2) during the 30 s and the peak of blood lactate concentration ([L]p) during the recovery were also measured. No difference in MAnP was observed between HA and LA. P, [L]p, and VO2 were lower at HA. This suggests that the altitude of 3,700 m did not affect the performance of the force-velocity test but reduced that of the Wingate test. This decrease in P was linked to a lower participation of glycolysis and aerobic metabolism. The latter is related to a reduced aerobic performance at HA. In addition, the slopes of the relationships between age and MAnP, P, and [L]p were the same at HA and LA, indicating that chronic hypoxia did not alter the development of the anaerobic metabolism during puberty.

Acclimatization↗
PubMed1989

Hormonal, fluid, and electrolyte changes during a 72-h recovery from a 24-h endurance run.

To examine body fluid regulation over 72 h of recovery from a 24-h endurance race, changes in plasma volume (delta PV) and plasma aldosterone (A), cortisol (CO), antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP) were studied in nine male runners before (C) and after (1-2 h = D0; 24 h = D1; 48 h = D2; 72 h = D3) the race, 24-h urine collections were made 1 week before (C), during the 24-h race/U0), and during the 3 days following the end of the race (U1, U2, and U3). On D0 delta PV decreased (2%). A, CO and ADH increased (380%, 200%, and 133%, respectively, from C values) and ANP decreased (68%). No significant changes were found in sodium, potassium, osmolality in plasma, in 24-h urine volume (UV), and natriuresis (Na+). Urinary potassium excretion (K+) increased (256% from C value). During the 3 days of recovery delta PV rose markedly with a peak on D2 (24%) and remained elevated on D3 (15%). CO, ADH, and ANP returned to baseline on D1 and A on D3. Significant inverse effects were observed on ADH (P less than 0.001) and ANP (P less than 0.01): from C values, ADH decreased (21% and 29%) and ANP increased (41% and 58%) on D2 and D3, respectively. UV and Na+ were depressed on D1 and D2. This study shows that the hormonal responses observed immediately after the 24-h run favored a relative fluid conservation. The hypervolemia that occurred during the 3-day recovery was related to renal responses on D1 and D2 and appeared to be the primary factor in the hormonal responses on D2 and D3.

Adult↗
PubMed1988

Enzymatic and hormonal responses following a 24 h endurance run and a 10 h triathlon race.

Muscle cell leakage and hormonal changes were compared immediately after and during the 3 days following a 24 h endurance run (R24h) in 8 subjects, and a 10 h triathlon non-competitive race (T10h) in 6 subjects. The study showed three main differences: 1) plasma enzyme increases were considerably more significant in R24h than in T10h: compared with resting levels, creatine kinase increased x 120 after R24h but only x 2 after T10h; lactic dehydrogenase x 4, as opposed to x 1.5; and transaminases only showed an increase after R24h. The plasma myoglobin increase after R24h was double that found after T10h; 2) for the same magnitude of plasma aldosterone and cortisol after R24h and T10h (3 times the resting levels), a highly significant decrease in urinary Na+ (p less than 0.001) and an increase in urinary K+ (p less than 0.01) were found only after R24h; and 3) the plasma free noradrenaline level increased significantly after R24h (x 2.6) whereas it was unchanged after T10h. In contrast, the plasma level of conjugated dopamine increased only after T10h (x 3.7, p less than 0.05). These results suggest that long-distance running causes more muscular lesions than the triathlon, and that important factors other than aldosterone are probably involved in the regulation of urinary electrolyte excretions during T10h.

Adult↗
PubMed1988

Anaerobic metabolism during pubertal development at high altitude.

In a previous study we showed that there were no differences in anaerobic metabolism between groups of 11-yr-old children living at high (3,700 m) and low (330 m) altitudes. The aim of this study is to investigate changes in this metabolism during pubertal development. We compare blood lactate concentration ([L]) after maximal bicycle exercise in 20 boys acclimatized to high altitude (HA, 12 yr old) and at low altitude in 14 boys (LA1, 12 yr old) and in 13 boys (LA2, 14 yr old). The subjects had the same level of physical fitness and the same nutritional and socioeconomic status. Pubertal development was identified by salivary testosterone concentration ([T]). Results (means +/- SE) showed 1) at the age of 12 years, [L] and [T] in HA were significantly higher than in LA1 ([L] was 9.2 +/- 0.5 vs. 6.8 +/- 0.5 mmol/l, [T] was 233 +/- 66 vs. 132 +/- 30 pmol/l), 2) [L] and [T] in HA were statistically the same as in LA2, and 3) a linear relationship between [L] and [T] was significant (P less than 0.05) in all HA and LA subjects. This suggests that the higher [L] in 12-yr-old boys living at HA could result in an enhanced anaerobic metabolism linked to an earlier gonadal maturation evaluated by testosterone level.

Adolescent↗
PubMed1986

Oxygen debt in submaximal and supramaximal exercise in children at high and low altitude.

The effect of high altitude (HA) on O2 debt and blood lactate concentration [( L]) was examined in 10- to 13-yr-old children who exhibited the same level of physical fitness. Fifty-one children acclimatized to HA (3,700 m) were compared with 40 children living at low altitude (LA, 330 m) during submaximal (20-95% maximal aerobic power, MAP), maximal and supramaximal (115% MAP) bicycle exercise. Results showed that 1) maximal O2 uptake (VO2max) and maximal heart rate were significantly (P less than 0.001) lower at HA than at LA by 15% and 11 beats X min-1, respectively; 2) for a given absolute work load, O2 debt was higher at HA than at LA, and the slopes of the linear relationships between O2 debt and O2 uptake were significantly higher at HA; 3) when related to percent of VO2max, O2 debts in HA and LA were similar; for 115% MAP maximal O2 debt and [L] were not significantly different (maximal O2 debt, 45.7 +/- 2.7 and 45.9 +/- 3.8 ml X kg-1; [L], 6.0 +/- 0.3 and 6.7 +/- 0.5 mM); and 4) linear relationships between maximal O2 debt and [L] were the same at HA and LA. This suggests that HA did not modify the anaerobic capacity in children.

Adolescent↗
PubMed1985

Effects of endurance training on the androgenic response to exercise in man.

Six healthy subjects, aged 35.8 +/- 4.4 years, volunteered to participate in a 40-week training program on a bicycle ergometer [three 60-min sessions per week at 80%-85% of maximal oxygen uptake (VO2 max)]. Before training and at the 10th, 20th, 30th, and 40th weeks of the training program, plasma testosterone, cortisol, and androstenedione concentrations were measured at rest (t0) and at the end (t60) of a 1-h endurance exercise requiring 85%-90% of VO2 max. Training resulted in significant increases of anaerobic threshold (12.6%) and VO2 max (7.3%). The training program did not significantly alter the resting values of plasma testosterone, androstenedione, and cortisol; in contrast, the exercise responses (delta = t60-t0) of testosterone, androstenedione, and cortisol were increased. The highest amplitude of these responses was reached at the 30th week for cortisol and androstenedione and at the 40th for testosterone. These results suggest that long-term training enhances both testicular adrenal and responses to endurance exercise. The possible role of hormonal changes in the mobilization of energy substrates during exercise is discussed.

Adult↗
PubMed1985

[Long-term radiology and respiratory function study following exposure to asbestos].

During the supervision of 93 workers in an asbestos factory pulmonary function tests and radiographs were performed using the same equipment and by the same team, at 5 yearly intervals. The assessment of radiographic changes was judged by following both the reader of the films and the technique used (either un-named films or simultaneous films at 5 yearly intervals). On reading un-named films the appraisal of parenchymal abnormalities was variable from one reader to another; on the other hand they were less marked for simultaneous readings made by the same observer. Progressive pulmonary function tests showed that the fall in vital capacity and of VEMS in 5 year intervals was more rapid when there was a parenchymal abnormality, when the duration of exposure was long or the subject was older when first exposed. The results showed that in spite of ceasing to be exposed the parenchymal abnormalities progressed.

Adult↗
PubMed1985

[Lessons from a long-term survey on the effects of massive occupational exposure to asbestos. The AMISOL affair 10 years later].

For the past 10 years the authors have followed up a cohort of workers who had been massively exposed to dust in an asbestos textile factory which closed down in 1974. They report on the difficulties of all kinds they encountered during this epidemiological survey. The most original result is that they were able to establish that the radiological and functional manifestations of asbestosis pursue their course after the subjects have ceased to be exposed. Another important point is the early development of lesions in peripheral bronchioles, detected by volume-flow loops. The authors insist on the psycho-social problems at the site of work or in daily life which arise from the use of asbestos or of fibres with similar properties. Social protection, at present well organized, should suppress the risk of asbestosis in Western countries. However, a number of problems remain to be solved, notably those concerning the long-term risk of pleural mesothelioma, the mode of action of the fibers and the immune reactions they induce, and the economic and social consequences of a hypothetical ban on asbestos--a material very difficult to replace. This study embodies, in miniature, all the problems of society associated with asbestos during this second half of the XX th century.

Asbestosis↗
PubMed1985

[Familial polycythemia caused by high oxygen affinity hemoglobin. 2nd world case of hemoglobin J Providence].

The cas observed in Auvergne and reported here raises the aetiological problem of polycythaemias. Young subjects with polycythaemia should be investigated for congenital anomaly of oxygen transport by measuring P50 and 2,3-DPG, which provides information on the oxygen-carrying capacity of haemoglobin. When confronted with familial polycythaemia due to high oxygen affinity haemoglobin, clinicians must know that a cause-effect relationship is not always demonstrable since other factors, such as tobacco-smoking in this particular case, may intervene.

Adult↗