Jean Coudert

Plasma free and sulphated catecholamines after ultra-long exercise and recovery

SummaryWe investigated the early and late effects of two types of ultra-long exercise on sympatho-adrenal and dopaminergic activity. With this aim both free and sulphoconjugated plasma catecholamines (CA), noradrenaline (NA), adrenaline (A), and dopamine (DA) were determined in two groups of athletes immediately after completion of 24-h running or a 10-h triathlon and on recovery during the next 1–3 days. Both races stimulated the sympathetic activity, but differences were observed in the CA pattern: the 24-h run induced a marked elevation of free and sulphoconjugated NA (+175% and +180%, respectively) but failed to alter significantly A and DA levels. The triathlon challenge increased the three conjugated CA (NA sulphate +350%; A sulphate + 110%; DA sulphate +270%) and to a lesser extent free CA (NA +45%; A +30%). On the first post-exercise morning, a sustained intense noradrenergic activity was still present in the 24h-runners, as evidenced by the large increase in free and sulphated NA levels (+ 140% and + 100%, respectively). Such a prolonged activity was also indicated after completion of the triathlon, by the increase of NA sulphate (+ 140%) observed on the 1st recovery day. However, after the triathlon there was a decreased release of A from the adrenal medulla for several days. These data show that both types of ultralong exercise are able to induce for several hours a sustained sympathetic activation during the test and in the recovery period. Furthermore, the study shows that plasma conjugated CA may provide delayed and cumulative indexes of sympathetic activation, complementary to the instantaneous markers such as free CA.

Effects of 14 weeks of progressive endurance training on energy expenditure in elderly people

Effects of progressive endurance training on energy expenditure (EE) were studied in thirteen elderly sedentary subjects (62.8 (SD 2.3) years) after 7 and 14 weeks of training. Daily EE (DEE) and energy cost of the various usual activities were measured over 48 h by whole-body indirect calorimetry. Free-living DEE (DEEFLC) was calculated from 7 d activity recordings and the energy costs of activities were measured in the calorimeters using the factorial method. DEEFLC did not vary significantly throughout the training period despite the additional energy cost of training sessions (0.60 (SD 0.15) MJ/d), because energy expended during free-living activities (EEACT) decreased by 4.8 (SD 7.1)% (P < 0.05) and 7.7 (SD 8.6)% (P < 0.01) after 7 and 14 weeks of training respectively. Measurements in the calorimeters showed that sleeping metabolic rate transiently increased by 4.6 (SD 3.2)% after 7 weeks of training (P < 0.001) and returned to its initial level after 14 weeks of training. BMR was 7.6 (SD 7.0)% (P < 0.01) and 4.1 (SD 6.1)% (P = NS) higher after 7 and 14 weeks of training respectively, than before training. Likewise, diet-induced thermogenesis increased from 3.7 (SD 2.5) to 7.2 (SD 2.8)% energy intake after 7 weeks of training (P < 0.05), and returned to its initial level after 14 weeks of training (4.2 (SD 2.6)% energy intake). Despite these changes, energy expended during activities and the corresponding DEE did not vary throughout the training period. It was concluded that: (1) DEEFLC remained constant throughout the training period due to a compensatory decrease in free-living EEACT; (2) progressive endurance training induced a transient increase in sleeping metabolic rate, BMR and diet-induced thermogenesis after 7 weeks which was not reflected in the energy expended during activities and DEE.

Expression of lactate dehydrogenase A and B genes in different tissues of rats adapted to chronic hypobaric hypoxia.

Lactate dehydrogenase (LDH) is a tetramer made up of two different subunits A and B. In cellular models, severe hypoxia increases LDH A gene expression whereas LDH B gene does not exhibit any regulation. The aim of our work was to characterise LDH expression in different tissues of rats bred at high altitude. For this purpose, we chose a Sprague–Dawley rat strain adapted to chronic hypoxia in La Paz (3700 m), Bolivia. Two normoxic control groups were bred at low altitude in Clermont‐Ferrand (350 m), France, one group was ad libitum with free access to food and water as was the hypoxic one, and the second normoxic group was nourished with the food intakes measured for the animals from La Paz. We measured total LDH specific activity, isoform distribution and LDH A and B mRNA amounts in three skeletal muscles (soleus, extensor digitorum longus (EDL), plantaris), heart and brain. Our study demonstrates that, unlike what has been shown in cellular models under severe hypoxia, LDH A gene is not systematically up‐regulated in tissues of rats living at high altitude. Furthermore, chronic hypoxia limits LDH B gene transcription or its mRNA stability in both soleus and EDL. These regulations occur at various molecular levels like gene transcription, mRNA stabilisation or translation and protein stability, depending on the tissue studied, and are partly attributed to caloric restriction provoked by high altitude. These data provide insight into LDH gene expression underlying the diverse and complex tissue‐specific response to chronic hypoxia. J. Cell. Biochem. 89: 67–79, 2003.

Intracellular hyperhydration induced by a 7-day endurance race.

Abstract To test the hypothesis that a chronic expansion of extracellular water (ECW), usually observed during prolonged endurance exercise, is associated with an increase in intracellular water space (ICW), total body water (TBW) and ECW were estimated before (within a week, day C-7) and after (on the 1st day of recovery, R+1) a competition lasting 7 consecutive days in nine healthy sportsmen. The competition involved running, cycling and cross-country skiing over 620 km. Between days C-7 and R+1, the following increases occurred – mean TBW by 4.2 (SEM 1.1) l (i.e. +10%, P = 0.01, bioelectrical impedance analysis, BIA, at 100 kHz) and by 4.1 (SEM 0.7) l (P = 0.01, dilution of 18O); mean ECW by 2.2 (SEM 0.5) l (i.e. +14%, P = 0.01, BIA at 5kHz), and mean plasma volume (PV) by 0.7 (SEM 0.1) l (i.e. +22%, Evans blue dye dilution, P = 0.008). Consequently, mean ICW had been expanded by 2.1 (SEM 0.6) l (i.e. +8%, P = 0.01). The intensity of daily exercise evaluated from recordings of heart rate varied between 49.0% to 57.8% of maximal oxygen consumption V˙O2max. Water retention was highly correlated with relative exercise intensity V˙O2max (ICW, r=0.86; ECW, r=0.93; TBW, r=0.94). Total mean plasma content of sodium increased by 104 (SEM 17) mmol (P = 0.008) while albumin and total protein contents were unchanged. We concluded that prolonged and repeated exercise induced a chronic hyperhydration at both extracellular and intracellular levels, which was related to exercise intensity. Sodium retention was the major factor in the increase of PV.

Daily energy expenditure, activity patterns, and energy costs of the various activities in French 12–16-y-old adolescents in free living conditions

Background: Changes in lifestyle and increases in sedentary activities during recent decades have been shown to contribute to the prevalence of overweight in adolescents.Objectives: To determine the inter-individual variability and the day-to-day variations in daily energy expenditure (DEE) and activity pattern, and the energy costs and EE of the various activities of adolescents in free-living conditions.Design: Sixty adolescents (four groups of 14–16 boys or girls aged 12–16 y) participated in this cross-sectional study during spring or autumn. Activity patterns and EE were determined during five consecutive days, using both a diary and the heart rate recording method validated by whole-body calorimetry and laboratory tests.Results: Mean DEE increased significantly with age in boys, but not in girls. However, the physical activity level did not vary significantly with sex and age. Mean DEE was significantly higher in spring than in autumn in the 12.6-y-old subjects. It was also 21% higher during the free days than during the schooldays in the active subjects, but 7% lower in the sedentary subjects. The energy cost of 22 activities was determined. Time and energy devoted to moderate and sport activities exhibited great inter-individual variability. They were lower in girls than in boys and decreased with age. The increase in EE resulting from moderate and sport activities instead of sedentary activities ranged from 0.2 to 2.7 MJ/day over the week.Conclusion: The great variability in DEE of adolescents resulted mainly from differences in the nature, duration and intensity of physical activities during the free days.

Daily energy expenditure and its main components as measured by whole-body indirect calorimetry in athletic and non-athletic adolescents

The objectives of the present study were to determine whether differences in usual physical activity affect BMR, sleeping energy expenditure (EE), and EE during seated activities between athletic and non-athletic adolescents, and to establish individual relationships between heart rate and EE. Adolescents (n 49, four groups of eleven to fifteen boys or girls aged 16-19 years) participated in the study. Body composition was measured by the skinfold-thickness method and maximum O2 consumption (VO2max) by a direct method (respiratory gas exchange) on a cycloergometer. The subjects each spent 36 h in one of two large whole-body calorimeters. They followed a standardized activity programme including two periods of exercise simulating their mean weekly physical activities. Fat-free mass (FFM), VO2max, daily EE and EE during sleep and seated activities were significantly higher in athletic than in non-athletic subjects of both sexes. VO2max, daily EE and EE during exercise adjusted for FFM were higher in athletic than in non-athletic adolescents (P < 0.001), whereas sleeping EE, BMR and EE during seated activities and adjusted for FFM were not significantly different between athletic and non-athletic adolescents. However, sex differences in EE remained significant. Thus, differences in EE between athletic and non-athletic adolescents resulted mainly from differences in FFM and physical exercise. Usual activity did not significantly affect energy utilization of substrates. Finally, individual relationships were computed between heart rate and EE with activity programmes simulating the usual activities of athletic and non-athletic adolescents with the goal of predicting EE of the same subjects in free-living conditions.

Effects of acute hypoxic exposure on prooxidant/antioxidant balance in elite endurance athletes.

We investigated whether acute hypoxic exposures could modify the pro-oxidant/antioxidant balance in elite endurance athletes, known to have efficient antioxidant status. Forty-one elite athletes were subjected to two hypoxic tests: one at an altitude of 4 800 m during 10-min of mild exercise (4 800 m test) and the second at rest for 3 h at an altitude of 3 000 m (3 000 m test). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric reducing antioxidant power (FRAP) and lipid-soluble antioxidants were measured before and immediately after the 4 800 m test and at the end of the 3 000 m test. The 4 800 m and the 3 000 m tests induced a significant increase in the level of MDA and AOPP (+7.1% and +71.7% for 4 800 m test and +8.6% and +40.9% for 3 000 m test). The changes in plasma MDA and arterial oxygen saturations were significantly correlated (r=0.35) during the 3 000 m test. FRAP values (-13%) and alpha-tocopherol (-21%) were decreased following the 3 000 m test. However, following the 4 800 m test, only alpha-tocopherol was decreased (-16%). These results provide evidence that the highly-trained athletes do not have the antioxidant buffering capacity to counterbalance free radical over-production generated by acute hypoxic exposure, with or without mild exercise.

Vasomotor Effects of Transcutaneous CO2 in Stage II Peripheral Occlusive Arterial Disease

Vasomotor effects of skin exposure to carbon dioxide (CO2) have been described in normal subjects. It was of interest, therefore, to determine whether percutaneous CO2 is of therapeutic benefit. In a randomized, double-blind study, 10 patients with lower limb arteriopathy (stage II) were investigated before and after local exposure for twenty minutes to CO2-rich spa gas or to water-vapor-saturated air at the same temperature as that CO2 -rich spa gas. Brachial and femoral blood flows, brachial and posterior tibial artery pressures, heart rate, and chest and foot transcutaneous oxygen tensions (tcPO2) were determined. Femoral blood flow, tibial pressure, and foot tcPO2 were significantly increased after exposure of the skin to CO2-rich spa gas. This effect was not accompanied with systemic hemodynamic modifications. Water-vapor-saturated air had no effect. These results suggest that transfer of CO2 across the skin can have beneficial local vasomotor effects in patients with lower limb stage II arteriopathy.

Effect of equilibrated hydration changes on total body water estimates by bioelectrical impedance analysis

The present study was performed to determine how equilibrated fluctuations in hydration affected the validity of bioelectrical impedance analysis (BIA) for body composition assessment. Total body water (TBW) expansion was induced by a 4 d endurance trial and the subsequent water loss was obtained over the recovery period. Twelve healthy men exercised on a cycle and treadmill alternately for 5 h/d over 4 d at moderate intensity. TBW, fat mass (FM) and fat-free mass (FFM) were assessed 3 d before the trial (control), and on the first and eighth day of recovery (R1 and R8 respectively). TBW was evaluated by (2)H dilution (TBW2H) as a reference method and by BIA (TBWBIA) at 100 kHz at the same time. TBW2H increased significantly between the control day and R1 by 1.87 (sd 1.11) litres (P=0.005) and TBWBIA by 1.38 (sd 1.56) litres (P=0.009). Both values returned to the control level on R8. For each period, TBW2H and TBWBIA did not differ significantly and were correlated (r(2) 0.85, P=0.0004 for the control day; r(2) 0.63, P=0.03 for R1; r(2) 0.75, P=0.02 for R8). Plasma Na concentration and osmolality did not differ between the control day, R1 and R8. FFM gain (1208 (sd 1983) g) and FM loss (-1168 (sd 906) g) between the control day and R1 were followed by a FFM decrease (-624 (sd 1281) g) and a FM increase (860 (sd 1212) g) between R1 and R8. As expected, these FFM and FM changes were significantly correlated with TBW variations. The present results provide evidence that BIA may be a useful method for estimating TBW when fluid shifts are equilibrated and electrolyte concentrations are unchanged. However, it is not a valid technique for assessing FM and FFM under these conditions.

The importance of socioeconomic and nutritional conditions rather than altitude on the physical growth of prepubertal Andean highland boys.

The aim of this work was to study the effect of hypoxic stress on the physical growth of prepubertal Bolivian boys (10-11.5 years of age) of the same socioeconomic and nutritional conditions. The subjects consisted of 143 boys living in La Paz (altitude 3600 m, n = 67) and Santa Cruz de la Sierra (altitude 420 m, n = 76). Among the boys studied at high altitude, 23 were from a high socioeconomic background (HA1) and 44 from a low socioeconomic background (HA2). The group studied at low altitude consisted of 47 boys from a high socioeconomic background (LA1) and 29 from a low socioeconomic background (LA2). A scientific evaluation of the nutritional status of the boys was realized from specific anthropometric characteristics (height, body weight, upper arm muscle circumference, body fat mass and body mass index) and haematological (haematocrit, haemoglobin, serum iron, serum ferritin, red cell protoporphyrin, transferrin saturation) and biochemical (total serum protein, albumin and prealbumin) parameters. At high as at low altitudes, the biometric characteristics of boys from a low socioeconomic background were significantly lower than those of boys from a high socioeconomic background. The physical growth of HA2 and LA2 boys was delayed by approximately 2 years. All the boys had biochemical and haematological parameters within the normal range. Boys from a low socioeconomic background were considered as marginally undernourished and those from a high socioeconomic background as well-nourished. Within the same socioeconomic class there was no nutritional difference between highland and lowland boys. Similarly, and this is the most important feature of this study, there was no difference for the overall biometric characteristics between highland and lowland boys of the same socioeconomic and nutritional status. Therefore, it appears that when socioeconomic and nutritional conditions are taken into account, there is no effect of hypoxic stress on the physical growth of prepubertal Andean highland boys.