Endurance training and insulin therapy need to be associated to fully exert their respective beneficial effects on oxidant stress and glycemic regulation in diabetic rats.

In type 1 diabetic subjects, hyperglycemia-induced oxidant stress (OS) plays a central role in the onset and development of diabetes complications. This study aimed to assess the benefits of an endurance training program and insulin therapy, alone or in combination, on the glycemic regulation, markers for OS, and antioxidant system in diabetic rats. Forty male Wistar rats were divided into diabetic (D), insulin-treated diabetic (D-Ins), diabetic trained (D-Tr), or insulin-treated diabetic trained (D-Ins+ Tr) groups. An additional healthy group served as control group. Insulin therapy (Lantus, insulin glargine, Sanofi) and endurance training (a treadmill run of 60 min/day, 25 m/min, 5 days/week) were initiated 1 week after streptozotocin-induced diabetes (45 mg/kg) and lasted for 8 weeks. At the end of the protocol, blood glucose and fructosamine levels, markers for skeletal muscle OS (CML, isoprostanes, GSH/GSSG) and antioxidant system (SOD and GPx activity, ORAC) were assessed. In diabetic rats, the glycemic control was altered and OS marker levels were increased, while the antioxidant system activity remained unchanged. Insulin treatment improved the glycemic regulation, the pro-antioxidant status, and contributed to the reduction of OS marker levels. Endurance training decreased OS marker levels without improving the antioxidant enzyme activity. Endurance training and insulin therapy acted independently (by different ways), but their association prolonged the insulin action and allowed a better adaptation of the antioxidant system. To conclude, our results demonstrate that combination of insulin treatment and endurance training leads to greater benefits on the glycemic regulation and oxidant status.

Physical inactivity, insulin resistance, and the oxidative-inflammatory loop.

Epidemiological data indicate that physical inactivity, a main factor of global energetic imbalance, is involved in the worldwide epidemic of obesity and metabolic disorders such as insulin resistance. Although the complex pathogenesis of insulin resistance is not fully understood, literature data accumulated during the past decades clearly indicate that the activation of the oxidative-inflammatory loop plays a major role. By activating the oxidative-inflammatory loop in insulin-sensitive tissues, fat gain and adipose tissue dysfunction likely contribute to induce insulin resistance during chronic and prolonged physical inactivity. However, in the past years, evidence has emerged showing that early insulin resistance also occurs after very short-term exposure to physical inactivity (1-7 days) without any fat gain or energetic imbalance. The possible role of liver disturbances or endothelial dysfunction is suggested, but further studies are necessary to really conclude. Inactive skeletal muscle probably constitutes the primary triggering tissue for the development of early insulin resistance. In the present review, we discuss on the current knowledge about the effect of physical inactivity on whole-body and peripheral insulin sensitivity, and how local inflammation and oxidative stress arising with physical inactivity could potentially induce insulin resistance. We assume that early muscle insulin resistance allows the excess nutrients to shift in the storage tissues to withstand starvation through energy storage. We also consider when chronic and prolonged, physical inactivity over an extended period of time is an underestimated contributor to pathological insulin resistance and hence indirectly to numerous chronic diseases.

Growth hormone replacement therapy prevents sarcopenia by a dual mechanism: improvement of protein balance and of antioxidant defenses.

The aim of our study was to elucidate the role of growth hormone (GH) replacement therapy in three of the main mechanisms involved in sarcopenia: alterations in mitochondrial biogenesis, increase in oxidative stress, and alterations in protein balance. We used young and old Wistar rats that received either placebo or low doses of GH to reach normal insulin-like growth factor-1 values observed in the young group. We found an increase in lean body mass and plasma and hepatic insulin-like growth factor-1 levels in the old animals treated with GH. We also found a lowering of age-associated oxidative damage and an induction of antioxidant enzymes in the skeletal muscle of the treated animals. GH replacement therapy resulted in an increase in the skeletal muscle protein synthesis and mitochondrial biogenesis pathways. This was paralleled by a lowering of inhibitory factors in skeletal muscle regeneration and in protein degradation. GH replacement therapy prevents sarcopenia by acting as a double-edged sword, antioxidant and hypertrophic.

Superoxide production pathways in aortas of diabetic rats: beneficial effects of insulin therapy and endurance training.

Superoxide (O 2 (·-) ) overproduction, by decreasing the nitric oxide ((·)NO) bioavailability, contributes to vascular complications in type 1 diabetes. In this disease, the vascular O 2 (·-) can be produced by the NADPH oxidase (NOX), nitric oxide synthase (NOS), and xanthine oxidase (XO). This study aimed to determine the contribution of each enzymatic pathway in hyperglycemia-induced O 2 (·-) overproduction, and the effects of an endurance training program and insulin therapy, associated or not, on the O 2 (·-) production (amount and related enzymes) in diabetic rats. Forty male Wistar rats were divided into diabetic (D), diabetic treated with insulin (D-Ins), diabetic trained (D-Tr), or diabetic insulin-treated and trained (D-Ins + Tr) groups. An additional healthy group was used as control. Insulin therapy (Glargine Lantus, Sanofi) and endurance training (treadmill run: 60 min/day, 25 m/min, 5 days/week) started 1 week after diabetes induction by streptozotocin (45 mg/kg), and lasted for 8 weeks. At the end of the protocol, the O 2 (·-) production in aorta rings was evaluated by histochemical analyses (DHE staining). Each production pathway was studied by inhibiting NOX (apocynin), NOS (L-Name), or XO (allopurinol) before DHE staining. Diabetic rats exhibited hyperglycemia-induced O 2 (·-) overproduction, resulting from NOX, NOS, and XO activation. Insulin therapy and endurance training, associated or not, decreased efficiently and similarly the O 2 (·-) overproduction. Insulin therapy reduced the hyperglycemia and decreased the three enzymatic pathways implicated in the O 2 (·-) production. Endurance training decreased directly the NOS and XO activity. While both therapeutic strategies activated different pathways, their association did not reduce the O 2 (·-) overproduction more significantly.

A new method to estimate energy expenditure from abdominal and rib cage distances.

The aim of this paper is to validate a new method of energy expenditure (EE) estimation stemming solely from the measurement of rib cage, abdominal and chest wall distances. We set out to prove that the variations of these distances, measured by two pairs of electromagnetic coils, lead to the estimation of the ventilation (VE) and the EE. Eleven subjects were recruited to take part in this study (27.6 ± 5.4 years; 73.7 ± 9.7 kg). Each subject participated in two tests. The objective of Test 1 was to determine the individual and group equations between the VE and EE during light to moderate activities while Test 2 compared the two pairs of electromagnetic coils with the indirect calorimetry so as to estimate EE in upright sitting and standing positions and during walking exercises. During Test 2, we compared EE measured by indirect calorimetry (EE(IC-Val-REF)) with EE estimated by the two pairs of electromagnetic coils through the application of: (1) the individual equation (EE(mag-Val-INDIV)) and (2) the group equation (EE(mag-val-GROUP)). The results show that there is no significant difference between EE(IC-Val-REF) and EE(mag-Val-INDIV) and between EE(IC-Val-REF) and EE(mag-val-GROUP) for each activity. Furthermore, the mean difference seems to show that the estimation of EE is better with the group equation. In conclusion, on the proven basis of this study we are able to validate this new method which permits the estimation of EE from abdominal and rib cage distances. This study also highlights the advantage of using a group equation to the estimate EE.

Estimates of ventilation from measurements of rib cage and abdominal distances: a portable device.

To validate a new device designed to measure ventilation (V(E)), tidal volume (V(T)), inspiratory time (T(I)), and expiratory time (T(E)) during daily life activities. The anteroposterior displacement of the rib cage and abdomen and the axial displacements of the chest wall and the spine were measured using two pairs of magnetometers. was estimated from these four signals, and was simultaneously measured using a spirometer. A total of 707, 732, and 1,138 breaths were analyzed in sitting, standing, and exercise conditions, respectively. We compared V(E), V(T), T(I), and, T(E) measured by magnetometers (V(E)mag, V(T)mag, T(I)mag, and T(E)mag) with V(E), V(T), T(I), and T(E) measured by a spirometer V(E)spiro, V(T)spiro, T(I)spiro, and T(E)spiro, respectively). For pooled data V(E)mag, V(T)mag, T(I)mag, and T(E)mag were significantly correlated (p < 0.001) with V(E)spiro, V(T)spiro, T(I)spiro, and T(E)spiro in sitting and standing positions and during the walking exercise. The mean differences, between V(E)mag, and V(E)spiro for the group, were 10.44, 10.74, and 12.06% in sitting, standing, and exercise conditions, respectively. These results demonstrate the capacity of this new device to measure V(E) with reasonable accuracy in sitting, standing, and exercise conditions.

Exercise-induced oxidative stress in overweight adolescent girls: roles of basal insulin resistance and inflammation and oxygen overconsumption.

HYPOTHESIS: Basal insulin resistance (IR) and inflammation exacerbate post-exercise oxidative stress (OS) in overweight adolescent girls. DESIGN: Cross-sectional study, effect of incremental ergocycle exercise until exhaustion on OS markers. PARTICIPANTS: Normal-weight (control) (n=17, body mass index (BMI): 20-24.2 kg/m(2)) and overweight adolescent girls (n=29, BMI: 24.1-36.6 kg/m(2)). MEASUREMENTS: Dietary measurement, physical activity assessment (validated questionnaires), fat distribution parameters (by dual-energy X-ray absorptiometry and anthropometry) and maximal oxygen consumption (VO2peak). Blood assays include the following: (1) at fasting state: blood cell count, lipid profile, and IR parameters (leptin/adiponectin ratio (L/A), homeostasis model assessment of IR, insulin/glucose ratio; (2) before exercise: inflammation and OS markers (interleukin-6 (IL-6), C-reactive protein (CRP), myeloperoxidase (MPO), reduced glutathione/oxidized glutathione ratio (GSH/GSSG), 15 F(2)alpha-isoprostanes (F(2)-Isop), lipid hydroperoxides (ROOH), oxidized low-density lipoprotein (ox-LDL)) and antioxidant status (superoxide dismutase (SOD), glutathione peroxidase (GPX), vitamin C, alpha-tocopherol and beta-carotene); and (3) after exercise: inflammation and OS markers. RESULTS: At rest, overweight girls had a deteriorated lipid profile and significantly higher values of IR parameters and inflammation markers, compared with the control girls. These alterations were associated with a moderate rest OS state (lower GSH/GSSG ratio, alpha-tocopherol/total cholesterol (TC) ratio and GPX activity). In absolute values, overweight girls exhibited higher peak power output and oxygen consumption (VO2peak), compared with the control girls. Exercise exacerbated OS only in the overweight group (significant increase in F(2)-Isop, ROOH and MPO). As hypothesized, basal IR and inflammation state were correlated with the post-exercise OS. However, the adjustment of F(2)-Isop, ROOH and MPO variation per exercise VO(2) variation canceled the intergroup differences. CONCLUSION: In overweight adolescent girls, the main factors of OS, after incremental exhaustive exercise, are not the basal IR and inflammation states, but oxygen overconsumption.

Athletic performance and weight changes during the "Marathon of Sands" in athletes well-trained in endurance.

The purpose of this study is to examine the effects of the "Marathon of Sands" (MS), a 7-day, self-sufficient-diet, multi-stage running race across a section of the Moroccan desert, on body weight and plasma volume variation (PVV) and the relationship of these factors to performance in athletes who are well-trained in endurance. Sixteen MS runners agreed to participate in this study. Weight and body composition were measured and venous blood samples were taken before the first stage (D0), after the third stage (D3) and at the end of the MS (after the sixth stage: D6). Haematocrit and haemoglobin were used to calculate PVV at (D0, D3, and D6). No significant plasma volume decrease was observed throughout the race. Significant decreases in total body weight (BW), fat-free mass (FFM) and fat mass (FM) were observed in D3 and D6 (-4.3%, -3.5%, -0.8%; and -6.1%, -5%, -1.1%, respectively, for BW, FFM and FM at D3 and D6). This study clearly shows that, despite extreme conditions, the MS did not lead to a significant PV decrease in athletes well-trained in endurance. This study also supports the hypothesis that significant body weight loss may not systematically affect performances during long duration multiple-stage races.

Comparison of total antioxidant capacity of salivary, capillary and venous samplings: interest of the salivary total antioxidant capacity on triathletes during training season.

AIM: Total antioxidant capacity (TAC) is an essential parameter to watch over defense system of athletes exposed to an oxidant stress during intensive periods of training. To control this parameter throughout the training period, repetitive biological samples are required. The TAC is usually investigated in venous blood which needs invasive withdrawings. Thus, we proposed to find alternatives to venous blood analysis by venepuncture, which is invasive, stressful and not allow a regular follow-up on athletes during annual training season. METHODS: We measured capillary and salivary TAC in 65 physically active subjects at rest and compared them to the venous TAC. We followed the evolution of venous and salivary TAC in 7 triathletes throughout an annual training period (March and June) corresponding to two different types of training. RESULTS: There was a good correlation between plasma venous and capillary TAC values (r=0.77; P<0.0001), but salivary TAC were significantly lower than the plasma ones and did not correlate. Venous and saliva TAC of triathletes were significantly higher in March compared to June. The variations of plasma and salivary TAC between the two periods of training were correlated (r=0.96; P<0.01). CONCLUSION: The capillary sampling can replace the venous one for TAC evaluation in routine assays for the follow-up of athletes. Even if saliva TAC did not reflect plasma TAC, it could be used in the follow-up of athletes since a strong correlation is found between the variation of saliva and plasma TAC during the training season.

Accuracy of physical working capacity 170 to estimate aerobic fitness in prepubertal diabetic boys and in 2 insulin dose conditions.

AIM: Exercise tests evaluate the effects of physical activity, which is one of the four recommendations for diabetes treatment. An adjusted and accurate measure of aerobic capacity in diabetic patients is thus needed. This study compared two estimates of aerobic fitness (maximal oxygen uptake vs physical working activity PWC170, i.e., the workload at a pulse of 170) and the usual versus a reduced insulin dose in preadolescent boys with type 1 diabetes mellitus. METHODS: Sixteen prepubertal type 1 diabetic boys performed a submaximal test, the PWC(170). Gas exchange values and capillary blood glucose levels were monitored and, when possible, the test was extended to exhaustion. In 7 boys, the test was performed twice on separate days. On one day they received their usual insulin dose and on the other, their short-acting insulin was reduced by 1/3; the two tests were held in random order. The 9 other children were tested only once after receiving their usual insulin dose. RESULTS: For the 16 boys who performed the test with the usual insulin dose, PWC(170) (W) and peak oxygen uptake (peak VO(2)) (L.min(-1)) correlated closely (r=0.81, P=0.002). Aerobic fitness did not change with insulin dose, but some hypoglycemic episodes occurred when insulin dose was not reduced. CONCLUSIONS: Since maximal effort does not add more information, routine use of the submaximal peak VO(2)-correlated test, the PWC(170), seems sufficient, possibly in association with a planned insulin dose reduction. This dose change does not interfere with performance, but could reduce the risk of hypoglycemia.

Effect of training and detraining on catecholamine responses to sprint exercise in adolescent girls.

Training is well known to influence catecholamine responses to exercise. In women, this training effect is still not well characterized and has been studied mostly in adults. Hence, we investigated in this longitudinal study, the effects of a 6-month sprint training program followed by 5 months of detraining on plasma catecholamine responses to a sprint exercise in young female subjects. Twelve healthy adolescent girls [training group (TG), n=6; control group (CG), n=6] took part in our study. TG participated in 6 months of supervised sprint training program (3 days/week) and has no training past whereas, CG continued with it's normal activity. A 6s-sprint test was performed on a cycle ergometer before training (P1) and after training (P2) in both the groups. TG only realized a 6s-sprint test after 5 months of detraining (P3). Blood lactate concentrations (La) as well as plasma adrenaline (A) and noradrenaline (NA) concentrations were measured at rest, immediately after the warm-up and the 6s-sprint and during recovery. Peak power W peak), expressed both in absolute and relative values, were significantly increased in TG in P2 (P<0.01) but did not change in CG. After the sprint-training period, the warm-up and the 6s-sprint induced plasma A increase and the maximal A concentrations were significantly higher than in P1 and P3 for TG only (P<0.05). Plasma A did not change in CG after 6 months. In P3, W peak and maximal lactate concentrations ([La]max) were significantly greater compared to P1 and P2 in TG (P<0.05). In CG, [La]max were significantly increased in P2 (P<0.05). The present study demonstrates that 6 months of sprint training in adolescent girls induce both an increase in performances and in A responses to sprint exercise. This adrenergic adaptation disappears after 5 months of detraining whereas the gain in performance is maintained. These new data may lead to practical considerations.

Changes in blood lipid peroxidation markers and antioxidants after a single sprint anaerobic exercise.

It has been well demonstrated that the principal factor responsible for oxidative damage during exercise is the increase in oxygen consumption. However, other theoretical factors (acidosis, catecholamine autoxidation, ischemia-reperfusion syndrome, etc.) that are known to induce, in vitro, oxidative damage may also be operative during short-term supramaximal anaerobic exercise. Therefore, we hypothesized that short-term supramaximal anaerobic exercise (30-s Wingate test) could induce an oxidative stress. Lipid peroxidation markers [serum lipid radical production detected by electron spin resonance (ESR) spectroscopy and plasma malondialdehyde (MDA) levels detected by the thiobarbituric acid reactive substances (TBARS) method], as well as erythrocyte antioxidant enzyme activities [glutathione peroxidase (GPx), superoxide dismutase (SOD)] and erythrocyte glutathione (GSH) levels, were measured at rest, after the Wingate test and during the 40 min of recovery. The recovery of exercise was associated with a significant increase (x2.7) in lipid radical production detected by ESR spectroscopy, as well as with changes in the erythrocyte GSH level (-13.6%) and SOD activity (-11.7%). The paradoxical decrease in plasma TBARS (-23.7%) which was correlated with the peak power developed during the Wingate test ( r=-0.7), strongly suggests that such exercise stimulates the elimination of MDA. In conclusion, this study demonstrates that short-term supramaximal anaerobic exercise induces an oxidative stress and that the plasma TBARS level is not a suitable marker during this type of exercise.

Effects of submaximal intensity cycle ergometry for one hour on substrate utilisation in trained prepubertal boys versus trained adults.

AIM: Substrate utilisation during exercise might be different in trained prepubertal boys compared to trained adults, so dietary advice usually given to endurance trained adults may need to be adapted for endurance trained children. EXPERIMENTAL DESIGN: subjects pedalled for 1 hour on an ergocycle at 40% or 60% of Wmax (maximal aerobic power). PARTICIPANTS: 14 boys and 13 adults active in endurance sport (swimming). MEASURES: pulmonary respiratory gas-exchange ratio [RER = VCO(2)/VO(2)], used as the equivalent of the non protein respiratory quotient (RQ), was measured at rest, at the 15(th), 30(th), 45(thv and 60(th) min of exercise in order to calculate energy expenditure. RESULTS: Relative resting energy expenditure was significantly higher in boys than in adults. During exercise, energy expenditure (EE) was significantly lower in children than in adults (p<0.001), whereas fat-free mass relative EE was only influenced by intensity. Relative EE from carbohydrates (EE(CHO)) was lower in children compared to adults, even if the highest intensity involves a higher EE(CHO) in both groups (p<0.05). Boys oxidised more lipid at 40% of Wmax than 60% of Wmax or adults at either intensity. CHO utilisation was significantly increased at 60% vs 40% of Wmax, yet lower in boys than in men (p<0.01). Lipids' use, in g x min(-1) x kg-1)FFM, was significantly higher in boys than in men at 40% of Wmax (p<0.01). CONCLUSION: Trained children, at rest, had greater fat-free mass energy expenditure than adults, which may be linked to growth processes that remain unclear. During exercise, in boys, the main observation was the increase in CHO dependence relative with the intensity. Thus, it appears that CHO feeding is as important in endurance-trained boys as in endurance-trained adults, especially when exercise intensity approaches that of competition or training sessions.

Effect of sprint duration (6 s or 30 s) on plasma glucose regulation in untrained male subjects.

AIM: We have explored in the following study the glucoregulatory responses (glycemia, insulinemia, catecholamines) at the end of 2 supramaximal tests of different durations. METHODS: Seven untrained male subjects (21.9+/-0.3 y) performed an isolated exercise of 6 s (T6) and a Wingate-test of 30 s. To determine the levels of lactate (La), plasma concentrations of glucose, insulin, adrenaline (A) and noradrenaline (NA), blood samples have been collected successively at rest, after a warm-up period of 15 min, immediately after T6 and T30, and after 5, 10, 20, and 30 min of recovery. RESULTS: Whether expressed as absolute or relative values, the peak power recorded during the 2 tests is statistically the same in T6 and T30. The maximal value of lactate (L(amax)) measured 5 min after the end of the 2 exercises is significantly greater after T30 (12.3+/-0.9 mmol x L(-1)) than after T6 (5.4+/-0.4 mmol x L(-1)) and T30 (4.2+/-0.2 mmol x L(-1)). No significant difference is observed between the plasma glucose concentrations recorded after the 2 tests until the first 10 min of recovery. However the plasma glucose values recorded after 20 and 30 min of recovery are significantly higher after T6 than after T30. Whatever the duration of the test, the insulinemia level remains unchanged at the end of the exercise and during the 30 min of recovery. On the other hand, the values of adrenaline and noradrenaline after T6 and T30 become considerably higher than those recorded at rest. However, the increase remains significantly higher after T30 (13.5+/-1.8 nmol x L(-1) for NA and 2.7+/-0.7 nmol x L(-1) for A) than after T6 (4.9+/-0.3 nmol x L(-1) for NA and 1.2+/-0.2 nmol x L(-1) for A). CONCLUSION: These results suggest that the mechanism responsible for increasing blood glucose surpass those which decrease it during supramaximal exercise. However, plasma glucose concentrations is affected by the duration of supramaximal exercise. The lower increase of plasma glucose concentration after T30 than after T6 might be explained by the resting of muscle glycogen stores which are more used during T30 than after T6, but in the absence of muscle glycogen content measurement we cannot conclude.

Training status (endurance or sprint) and catecholamine response to the Wingate-test in women.

The aim of this study was to verify if, as for men, training status induces different catecholamine responses to exercise. To do this, we investigated the effect of training status (sprint or endurance) on plasma catecholamine response to a supramaximal exercise in women. Nineteen subjects took part in our study: six untrained subjects (UT), seven endurance trained subjects (ET) and six sprint trained ones (ST). The trained subjects (ET and ST) were all competing at a high national level. The maximal power (W max ) and the mean power (W) were determined from the Wingate-test. Blood lactate, adrenaline (A) and noradrenaline (NA) were analysed at rest (La 0, A 0 and NA 0 ), immediately at the end of the exercise (A max and NA max ) and after 5 min recovery (La max [3 min in arterialized blood], A 5 and NA 5 ). The disappearance of A and NA was judged by the ratio (A max -A 5 )/A max and (NA max -NA 5 )/NA 5. The ratio A max /NA max was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. As expected, during the Wingate-test ST exhibited significantly higher performances compared to UT and ET. But in contrast to the men's data no difference was observed between the three groups both for La max (13.1 +/- 0.8 mmol x L (-1); 14.8 +/- 1.0 mmol x L (-1) and 11.2 +/- 0.5 mmol x L (-1) respectively for ET, ST and UT), NA max (22.1 +/- 1.2 nmol x L (-1); 13.1 +/- 2.4 nmol x L (-1) and 20.2 +/- 7 nmol x L (-1)respectively for ET, ST and UT) and A max (4.1 +/- 0.8 nmol x L (-1); 2.6 +/- 0.6 nmol x L (-1); 13.1 +/- 0.6 nmol x L (-1) respectively for ET, ST and UT). Consequently the ratio A max /NA max was similar in UT, ET and ST (respectively 0.2 +/- 0.03; 0.2 +/- 0.04; 0.17 +/- 0.04), These results indicated, in contrast to the men's data, that the catecholamine response to the Wingate-test did not differ between female subjects of different status of training. In conclusion this study did not find any significant effect of training status on the catecholamine response to supramaximal exercise and so argues in favour of sex differences in response to training.

Effect of training status on the sympathoadrenal activity during a supramaximal exercise in human.

BACKGROUND: The study investigated the concentrations of plasma catecholamine, adrenaline (A) and noradrenaline (NA), and the adrenal medulla responsiveness to the sympathetic nervous activity in sprinters (S), endurance runners (E) and untrained subjects (U) during a supramaximal exercise (the Wingate-test). METHODS: A group of 19 men took part in the tests: 6 S (20.5+/-0.7 years), 6 E (21.0+/-1.0 years) and 7 U (20.9+/-0.4 years). The maximal power (Wmax) and the mean power (W) were determined from the Wingate-test on a cycle ergometer. The plasma lactate, A and NA were analysed at rest (La0, A0 and NA0), immediately at the end of the exercise (Amax and NA(max)) and after 5 min recovery (La(max), A5 and NA5). The disappearance of A and NA was judged by the difference between the maximal values and those determined after 5 min recovery (Amax-A5 and NA(max)-NA5) and the ratio A/NA was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. RESULTS: During the Wingate-test S exhibited higher performances and higher La(max) than the two other groups. At the end of the Wingate-test the NA(max) values were similar in the three groups whereas the Amax values were significantly higher in S than in E and U (8.00+/-0.5 nmol x l(-1) in S vs 3.47+/-0.30 nmol x l(-1) and 3.29+/-1.14 nmol x l(-1) respectively in E and U). This leads to a higher Amax/NA(max) ratio for S compared to the other two groups (0.77+/-0.10 in S vs 0.23+/-0.03 and 0.28+/-0.05, respectively in E and U). As the disappearance of A (Amax-A5) was significantly higher in S (6.80+/-0.47 nmol x l(-1) in S vs 2.64+/-0.19 nmol x l(-1) and 1.64+/-1.37 nmol x l(-1), respectively in E and U), the higher values of Amax in S could be explained by an increase of the adrenal medullary secretory capacity in this group. CONCLUSIONS: It was concluded that essentially short term and intense exercises as sprint ones or interval-training may alter the adrenal medulla responsiveness to supramaximal exercise but not long duration exercises.

Physiological profile of handball players.

BACKGROUND: The purpose of this study was to determine the physiological profile of handball players compared to sprinters, endurance trained and untrained subjects. METHODS: Forty-six subjects aged between 19 and 28 years took part in this study: 10 were national handball players (NHB); 7 were international handball players (IHB), 11 were sprint trained subjects (ST); 8 were endurance trained subjects (ET); and 10 were untrained subjects (UT). They performed an incremental treadmill test to determine the maximal oxygen uptake (VO2max), and a Wingate anaerobic test (WanT) to determine maximal power (Wmax). Plasma lactate (La) concentration was measured 5 minutes after the end of the Wingate-test. RESULTS: The VO2max of NHB was similar to that of the IHB and ST athletes but higher than that of the untrained and lower than the endurance trained athletes. Values for Wmax were similar in the IHB and NHB groups and very close to the sprinters. When normalized for body mass or to lean body mass, Wmax was greater in handball players when compared to untrained or endurance trained subjects. Lactate values were in the same range in the NHB, IHB and ST groups and were statistically higher in the NHB and IHB groups than in the UT or ET groups. CONCLUSIONS: The results suggest that the anaerobic metabolism seems to be important for the handball players similarly to sprinters. Since handball is known as a sport with typically short exercise periods of high intensity alternating with rests, anaerobic metabolism appears then to be higbly relevant to performance.

Glucose tolerance during moderate prolonged exercise in women with oral contraceptives as compared to non-users.

BACKGROUND: The purpose of this study was to assess gluco-se tolerance during exercise in women on oral contraceptives. METHODS: To this end, we investigated the effects of glucose ingestion on glucose and hormonal responses in 7 women on oral contraceptives (OC(+); 21.3+/-1.3 yrs) and 7 normally menstruating (OC(-); 22.6+/-1.3 yrs) during an ergocycle test (30 min, 60% VO2max). Venous blood samples were withdrawn at 0, 3, 5, 10, 15 and 30 min exercise and at the 30th min postexercise. Glucose was ingested per os (0.5 g x kg(-1) b.w) between the 2nd and the 3rd min of the exercise. RESULTS: Under resting condition, plasma glucose and catecholamine concentrations were similar in both groups whereas plasma GH and insulin levels were greater in OC(+) (p<0.05). Glucose/insulin ratio (G/I), used as an indicator of insulin resistance, suggested a reduced insulin sensitivity at rest in the OC(+) (p<0.05). No significant differences were observed between OC(+) and OC(-) in plasma glucose, insulin, and catecholamine concentrations during exercise. Plasma GH values were greater in OC(+) from the 15th min of the exercise and during the recovery period (p<0.01). CONCLUSIONS: This study indicated that oral glucose ingestion at the onset of prolonged submaximal exercise induced similar glucose tolerance in women taking or not oral contraceptives.

Effects of glucose ingestion at the onset of moderate-intensity, prolonged exercise in women as compared to men.

To test glucose tolerance during exercise, the effects of oral glucose ingestion (0.5 g x kg(-1)) on plasma glucose and hormonal responses (insulin, catecholamines) were investigated in 11 women [mean (SEM) age 21.6 (1.3) years] and 10 men [22.0 (0.3) years] during cycle ergometer exercise (30 min at 60% maximum oxygen consumption, VO(2max)). The two groups exhibited similar VO(2max) values, when expressed per kg of lean body mass. Venous blood samples (5 ml) were withdrawn immediately before the exercise, during the exercise (at 3, 5, 10, 15 and 30 min) and at the 30th min of the recovery period. Glucose was ingested orally between the 2nd and the 3rd min of the exercise. As compared to men, plasma glucose concentrations were lower in women during exercise (P < 0.05 at 3, 15 and 30 min) and at the 30th min of the recovery period (P < 0. 001), while plasma insulin concentrations were higher in women during exercise (P < 0.05 at 3, 15 and 30 min). The ratio of the area under the curve for glucose over the area under the curve for insulin was lower in women during exercise (P < 0.0002). A linear relationship between glucose and insulin concentrations was found only for women during exercise (r = 0.615, P < 0.0001). No gender difference was observed for the catecholamine concentration during exercise. In conclusion, this study postulates that an oral glucose load given at the onset of a prolonged and moderate exercise bout induced lesser plasma glucose and greater insulin concentrations in women as compared to men. These data argue in favour of a greater glucose tolerance in women during exercise.

Between 21 and 34 years of age, aging alters the catecholamine responses to supramaximal exercise in endurance trained athletes.

The purpose of this study was to determine the effect of aging and training on the adrenaline (A) and noradrenaline (NA) responses during the Wingate-test in three age groups of subjects: 21 year old untrained subjects (21U), 21 year old endurance trained (21T) (national elite runners), 34 year old endurance trained (34T) (national elite runners). Performances during the test were judged using the usual parameters of peak power (Wmax) and mean power (W) expressed in absolute or relative values. A and NA responses were measured at rest (A0 and NA0) immediately at the end of the exercise (Amax and NAmax) and after 5 minutes recovery (A5 and NA5). Plasma maximal lactate (La(max)) was determined 3 minutes after the end of the exercise. Wmax, W and La(max) were always significantly lower in 34T compared to 21T and 21U. The catecholamine responses were similar in 21T and 21U. Inversely, a significantly lower value of Amax was observed in 34T (2.01 +/- 0.5 nmol x l(-1)) compared to 21U (3.62 +/- 0.3 nmol x l(-1)) associated with a significantly higher value of NA(max) in 34T versus 21T and 21U. Thus, the Amax/NA(max) ratio was found to be significantly lower in the older subjects versus both 21T and 21U. All these findings indicated that endurance training did not affect the sympathoadrenergic responses to a supramaximal exercise and suggested that only one decade may reduce the capacity of the medulla to secrete adrenaline and therefore the adrenal medulla responsiveness to the sympathetic nervous activity.