Éditeur(s) : HAL CCSD ACSM
Résumé : International audience
PURPOSE AND METHODS: This study was designed to compare the physiological responses and performance of well trained cyclists riding with two different chainring designs, round or eccentric, during a brief and intense cycling exercise: an "all-out" 1-km laboratory test. The eccentrically designed chainring was made of two crank arms sliding into each other, with the inside arm fixed on the center of the arm of a circular chainring and the outside arm sliding along the inside and revolving around an elliptical cam. This design increases crank arm length at the downstroke and decreases it during the upstroke, thus increasing and decreasing the torque. In terms of the chainring's revolution, the crank arm length at 0 degrees and 180 degrees is similar to the arm length of circular chainrings (175 mm). However, during the downstroke (0-180 degrees ), it increases to its maximum length of 200 mm at 90 degrees and then returns to its original length of 175 mm at 180 degrees. During the upstroke, it decreases to a minimum length of 150 mm at 270 degrees and then increases to 175 mm at 360 degrees. Eleven cyclists performed an all-out 1-km laboratory test using each chainring. The study was conducted over two consecutive weeks with the order of chainring use randomized. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. Heart rate was measured using a telemetry system. RESULTS: None of the cardiorespiratory variables showed significant differences between chainring trials. Performance, however, was significantly improved using the eccentric design (64.25 +/- 1.05 vs 69.08 +/- 1.38 s, P < 0.004, with the eccentric and the round design, respectively). CONCLUSION: We concluded that the eccentric chainring significantly improved the cycling performance during an all-out 1-km test. Further testing with indoor cycling specialists performing on a velodrome would be helpful to define the maximal possibilities of such a chainring.
Medicine & Science in Sports & exercise

hal-00720551
https://hal.univ-antilles.fr/hal-00720551
https://hal.univ-antilles.fr/hal-00720551/document
https://hal.univ-antilles.fr/hal-00720551/file/Article.pdf

Éditeur(s) : HAL CCSD Ferrata Storti Foundation
Résumé : International audience
The aim of the study was to determine the factors associated with resting and exercise-induced hemoglobin oxygen desaturation. The well-established six-minute walk test was conducted in 107 sickle cell children (50 with sickle hemoglobin C disease and 57 with sickle cell anemia) at steady state. Hemoglobin oxygen saturation was measured before and immediately after the six-minute walk test. Blood samples were obtained on the same day to measure hematologic and hemorheological parameters. Exercise-induced hemoglobin oxygen desaturation was defined as a drop in hemoglobin oxygen saturation of 3% or more at the end of the six-minute walk test compared to resting levels. No children with sickle hemoglobin C disease, but approximately 50% of children with sickle cell anemia showed mild or moderate oxygen desaturation at rest, which was independently associated with the percentage of reticulocytes. Exercise-induced hemoglobin oxygen desaturation was observed in 18% of children with sickle hemoglobin C disease and 34% of children with sickle cell anemia, and was independently associated with the six-minute walk test, acute chest syndrome rate and the strength of red blood cell aggregates in children with sickle cell anemia. No association was found in children with sickle hemoglobin C disease between exercise-induced hemoglobin oxygen desaturation and the measured parameters. Hemoglobin oxygen desaturation at rest was common in children with sickle cell anemia but not in children with sickle hemoglobin C disease, and was mainly associated with greater hemolysis. Physiological strain during exercise and red blood cell aggregation properties may predict the occurrence of exercise-induced hemoglobin oxygen desaturation in children with sickle cell anemia.
ISSN: 0390-6078

inserm-00838989
http://www.hal.inserm.fr/inserm-00838989
http://www.hal.inserm.fr/inserm-00838989/document
http://www.hal.inserm.fr/inserm-00838989/file/Waltz_et_al._Ferrata_Storti_Foundation.pdf
DOI : 10.3324/haematol.2013.083576

Éditeur(s) : HAL CCSD
Résumé : International audience
Previous studies have reported respiratory, cardiac and muscle changes at rest in triathletes 24 h after completion of the event. To examine the effects of these changes on metabolic and cardioventilatory variables during exercise, eight male triathletes of mean age 21.1 (SD 2.5) years (range 17-26 years) performed an incremental cycle exercise test (IET) before (pre) and the day after (post) an official classic triathlon (1.5-km swimming, 40-km cycling and 10-km running). The IET was performed using an electromagnetic cycle ergometer. Ventilatory data were collected every minute using a breath-by-breath automated system and included minute ventilation (V(E)), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio, ventilatory equivalent for oxygen (V(E)/VO2) and for carbon dioxide (V(E)/VCO2), breathing frequency and tidal volume. Heart rate (HR) was monitored using an electrocardiogram. The oxygen pulse was calculated as VO2/HR. Arterialized blood was collected every 2 min throughout IET and the recovery period, and lactate concentration was measured using an enzymatic method. Maximal oxygen uptake (VO2max) was determined using conventional criteria. Ventilatory threshold (VT) was determined using the V-slope method formulated earlier. Cardioventilatory variables were studied during the test, at the point when the subject felt exhausted and during recovery. Results indicated no significant differences (P > 0.05) in VO2max [62.6 (SD 5.9) vs 64.6 (SD 4.8) ml x kg(-1) x min(-1)], VT [2368 (SD 258) vs 2477 (SD 352) ml x min(-1)] and time courses of VO2 between the pre- versus post-triathlon sessions. In contrast, the time courses of HR and blood lactate concentration reached significantly higher values (P < 0.05) in the pre-triathlon session. We concluded that these triathletes when tested 24 h after a classic triathlon displayed their pre-event aerobic exercise capacity, bud did not recover pretriathlon time courses in HR or blood lactate concentration.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720432
https://hal.univ-antilles.fr/hal-00720432
https://hal.univ-antilles.fr/hal-00720432/document
https://hal.univ-antilles.fr/hal-00720432/file/Article_2.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Tropical climate imposes a high level of physiological stress, which could modify the target heart rate in training load prescription, as the recommendations are often determined by maximal oxygen uptake testing in temperature-neutral laboratories. To test this hypothesis, 7 highlevel cyclists performed two randomised maximal tests in neutral (19.2±0.9 ◦C; 51.7±1.3% RH) and Tropical environment (25.8±1.1 ◦C; 63.7±2.3% RH). Neither maximal oxygen uptake nor ventilatory threshold was influenced by the environmental conditions. However, ventilation (p < 0.005) and the respiratory equivalent in O2 (p < 0.05) were significantly higher in the Tropical environment, whereas maximal power output and the time to attain maximal oxygen uptake were significantly lower (p < 0.05 for both). Moreover, the ventilatory cost of cycling (expressed in LW−1) was significantly greater in the Tropical condition (0.40±0.03 LW−1 vs. 0.32±0.05 LW−1, in Tropical vs. Neutral; condition effect: p < 0.005; condition×time: p < 0.001). Rectal temperature was influenced by neither the environmental conditions nor exercise (36.7±0.1 and 37.0±0.1 ◦Cvs. 36.8±0.1 and 37.1±0.2 ◦C, in Tropical vs. Neutral, before and after exercise) but was influenced by condition×time (p < 0.05). The heart rate (HR) values usually used for training prescription were not significantly different (154±5 bpm vs. 156±4 bpm and 172±4 bpm vs. 167±4 bpm in Tropical vs. Neutral climate, for the first and second thresholds, respectively). We concluded that the usual parameters measured during maximal exercise to establish training programs are not impaired in moderate Tropical environment. Nevertheless, the thermal stress attested by the increased ventilatory cost of cycling could have prevented the cyclists from performing a true maximal test in Tropical conditions.
ISSN: 1440-2440

hal-00703461
https://hal.univ-antilles.fr/hal-00703461
DOI : 10.1016/j.jsams.2009.11.004

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Sickle cell anemia (SCA or SS homozygous sickle cell disease) is an inherited blood disorder caused by single 12 nucleotide substitution in the ␤-globin gene that renders their hemoglobin (HbS) much less soluble than normal hemoglobin 13 (HbA) when deoxygenated. The polymerization of HbS upon deoxygenation is the basic pathophysiologic event leading to 14 RBC sickling, hemolysis, vasoocclusion and ultimately to chronic organ damage. The metabolic changes imposed by exercise 15 may initiate sickling and vaso-occlusive episodes. Further, in patients with SCA, exercise limitation may be related to anemia 16 or chronic complications such as pulmonary vascular disease, congestive heart failure and chronic parenchymal lung disease. 17 Few studies have investigated the cardiorespiratory responses of patients with SCA during either symptom-limited maximal 18 exercise test on cyclo-ergometer or during a six minute walk test. Therefore, patients are advised to start exercise slowly and 19 progressively, to maintain adequate hydration during and after exercise, to avoid cold exposure or sudden change in temperature, 20 and to avoid sports associated with mechanical trauma. There are, however, lack of evidence to allow practitioners to prescribe 21 an exercise program for patients with SCA, and individuals are usually encouraged to exercise on a symptom-limited basis. 22 Finally, this review will also highlight the basic principles that are often used for exercise practice and could be used for exercise 23 prescription and rehabilitation in patients with sickle cell anemia.
ISSN: 1386-0291

hal-01163966
https://hal.univ-antilles.fr/hal-01163966
DOI : 10.3233/CH-2011-1465

Éditeur(s) : HAL CCSD ACSM
Résumé : International audience
PURPOSE AND METHODS: This study was designed to determine whether the physiological responses elicited during the run part of repeated bouts of cycle-run exercise are similar to those required during the run segment of a cycle-run succession. Thirteen male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 20 min of running (C-R), and 4) five repeated bouts of 6 min of cycling and 4 min of running (X-CR). During the C-R and X-CR trials, venous blood samples were obtained to measure lactate, epinephrine and norepinephrine concentrations. During all trials, ventilatory data were collected every min using an automated breath-by-breath system. RESULTS: The results showed that 1) the cardiorespiratory responses observed during running were similar in the X-CR and C-R trials, 2) the lactate concentration was similar in both trials, 3) the epinephrine concentration was greater (277.9 +/- 11.9 vs 169.8 +/- 86.7 pg x mL(-1), P < 0.025) in X-CR than in C-R, and 4) the norepinephrine concentration was similar in both trials, except at the first cycle-run succession (T1) of X-CR. CONCLUSION: We concluded that 1) multi-block training is a good method to stimulate the specific adaptations required for the cycle-run succession, and particularly for the cycle-run transition, and 2) multi-block training seems to induce a greater catecholaminergic response, which may be due to a combination of an inherent effect of this type of training and the triathletes' relative lack of experience with it. In any case, the efficacy of the multi-block model needs to be more thoroughly evaluated over the course of a longer-term training program.
Medicine & Science in Sports & exercise

hal-00720475
https://hal.univ-antilles.fr/hal-00720475
https://hal.univ-antilles.fr/hal-00720475/document
https://hal.univ-antilles.fr/hal-00720475/file/Article_2_.pdf

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Because of the metabolic changes induced by a physical activity, the hemorheological properties of patients with sickle cell anemia could be further impaired and increase the risks for vaso-occlusive complications. However, few studies suggest that moderate physical activity could be beneficial rather than harmful in patients with sickle cell anemia (SCA). However, the definition of what can be considered as a moderate physical activity in SCA patients is imprecise. The present study tested the effects of a short incremental cycling exercise test conducted until the first ventilatory threshold on different biomarkers. Hematological and hemorheological parameters were compared between 8 patients with SCA and 13 healthy subjects (CONT) before, immediately after the end of the exercise and at 12, 36 and 60 hours after the exercise. We observed no significant hematological or hemorheological alteration induced by the exercise in the two groups. However, the exercise resulted in a delayed improvement of the red blood cell disaggregation threshold at 36 and 60 hrs after exercise in the SCA group which was paralleled to the decrease in the platelet count in this group. The present study suggests that such an exercise might be beneficial for microcirculatory blood flow.
ISSN: 1386-0291

hal-01137567
https://hal.univ-antilles.fr/hal-01137567

Éditeur(s) : HAL CCSD American College of Sports Medicine (ACSM)
Résumé : International audience
PURPOSE AND METHODS: To determine the effects of cycling on a subsequent triathlon run, nine male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 5 km of running (C-R), and 4) 30 min of running followed by 5 km of running (R-R). Before and 10 min after the third and fourth trials, the triathletes underwent pulmonary function testing including spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R and R-R trials, arterialized blood samples were obtained to measure arterial oxygen pressure (PaO2). During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. RESULTS: The results showed that 1) the oxygen uptake (VO2) observed during subsequent running was similar for the C-R and R-R trials; 2) the ventilatory response (VE) during the first 8 min of subsequent running was significantly greater in the C-R than in R-R trial (P < 0.05); 3) only the C-R trial induced a significant increase (P < 0.05) in residual volume (RV), functional residual capacity (FRC), and the ratio of residual volume to total lung capacity (RV/TLC); and 4) although a significant decrease (P < 0.05) in DL(CO) was noted after C-R, no difference between the two exercise trials was found for the maximal drop in PaO2. CONCLUSIONS: We concluded that 1) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle fatigue and/or exercise-induced hypoxemia, and 2) the greater VE observed during the first minute of running after cycling was due to the specificity of cycling. This reinforces the necessity for triathletes to practice multi-trial training to stimulate the physiological responses experienced during the swim-cycle and the cycle-run transitions.
ISSN: 0195-9131

hal-00720412
https://hal.univ-antilles.fr/hal-00720412
https://hal.univ-antilles.fr/hal-00720412/document
https://hal.univ-antilles.fr/hal-00720412/file/Article.pdf

Éditeur(s) : HAL CCSD ACSM
Résumé : International audience
The aim of this study was to examine the effects of the cycle-run and run-cycle successions of the triathlon and duathlon, respectively, on respiratory muscle strength and endurance. Methods: Respiratory muscle strength was assessed by measuring maximal inspiratory (P1max) and expiratory {PEmax) pressures. Respiratory muscle endurance was assessed by measuring the time limit (Tlim). Twelve triathleles participated in a three-trial protocol. The first trial consisted of an incremental cycle test to assess the maximal oxygen uptake (VO2max) of triathletes. Trial 2 consisted of 20 min of cycling followed by 20 min of running (C-R), and trial 3 consisted of 20 min of running followed by 20 min of cycling (R-C). Trials 2 and 3 were performed at the same metabolic intensity (% VO2max). P1max and P1max were measured before and 10 min after C-R and R-C, and I min after the post-C-R and post-R-C Tlim measurements (P1max l'). Tlim was measured I d before and 30 min after C-R and R-C. Results: The results showed a significant decrease in P1max after C-R (126.7 ± 4.3 cmH2O, P < 0.05) and R-C (123.7 ± 4.9 cmH2O, P < 0.05) compared with the baseline values (130 ± 3.8 and 129.6 ± 4.3 cmH2O, respectively). P1max 1' showed a significantly greater decrease after R-C versus C-R(111.2 ± 5.5 cmH2O vs 121.2 ± 3.9 cmH2O,respectively, P < 0.001). Tlim after C-R (3.3 ± 0.3 min) decreased significantly compared with baseline values (4.19 ± 0.3min and 4.02 ± 0.3 min, respectively). However, the Tlim decrease after R-C was significantly greater than after C-R (P < 0.001). Conclusion: We concluded that respiratory muscle strength and endurance were less decreased after the cycle-run succession and that cycling induced a greater decrease in respiratory muscle endurance than running.
Medicine & Science in Sports & exercise

hal-00720796
https://hal.univ-antilles.fr/hal-00720796

Éditeur(s) : HAL CCSD Thieme Publishing
Résumé : International audience
To determine the effect of triathlete performance level on the cardiorespiratory responses elicited by the cycle-run succession, eight regionally and nationally-ranked (Competitive) and five internationally-ranked (Elite) male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 20 min of running (C-R), and 4) a 20-min control run (R) at the same speed as the run in C-R. Before and 10 min after the third and fourth trials the triathletes underwent lung function testing: spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R trial blood samples were drawn to measure venous lactate concentration. During all trials ventilatory data were collected every minute using an automated breath-by-breath system. The results showed that 1) the oxygen uptake (VO2) of post-cycling running versus running alone was similar for both groups; 2) the ventilatory responses (VE, VE/VO2, VE/VC02 and f) of C-R running versus R were significantly higher (P < 0.005) for the Competitive group; and 3) a significant decrease (P< 0.05) in DL(CO) was also noted after the C-R trial in the Competitive group but not in the Elite group. We concluded that 1) the ventilatory responses during a run subsequent to cycling may be related to the triathlete performance level, and 2) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle alteration and exercise-induced hypoxemia in the Competitive triathletes.
ISSN: 0172-4622

hal-00720719
https://hal.univ-antilles.fr/hal-00720719

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
In order to study the effect of a competitive triathlon season on maximal oxygen uptake (VO2max), aerobic power (AeP) and anaerobic performance (AnP) of the lower limbs, eight triathletes performed exercise tests after: (1) a pre-competition period (Pre-COMP) (2) a competitive period (COMP), and (3) a low (volume and intensity) training period (Post-COMP). The tests were a vertical jump-and-reach test and an incremental exercise test on a cycle ergometer. Ventilatory data were collected every minute during the incremental test with an automated breath-by-breath system and the heart-rate was monitored using a telemetric system. RESULTS: No changes in VO2max were observed, whereas AeP decreased after Post-COMP compared to Pre-COMP and COMP and AnP decreased during COMP compared to Pre-COMP and Post-COMP. In addition, second ventilatory threshold (VT2) and power output at first ventilatory threshold (VT1) and VT2 decreased after Post-COMP. CONCLUSION: This study showed that six weeks of low volume and intensity of training is too long a period to preserve adaptations to training, although a stable maximal oxygen uptake throughout the triathlon season was observed. Moreover, the AnP decrease during COMP was probably in relation with the repetitive nature of the training mode and/or triathlon competitions.
ISSN: 0905-7188

hal-00720811
https://hal.univ-antilles.fr/hal-00720811
https://hal.univ-antilles.fr/hal-00720811/document
https://hal.univ-antilles.fr/hal-00720811/file/Sms-10170.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
This study compared the hemorheological profile at rest and in response to a short supramaximal exercise test between sickle cell trait (SCT) carriers and a control group. Eight SCT carriers and eight control subjects performed a ramp exercise test on a cycle ergometer conducted to maximal oxygen uptake ðV_ O2maxÞ: One week later, they performed a supramaximal exercise test consisting of pedaling for 1 min at 110% V_ O2max: Blood viscosity (gb), plasma viscosity (gp), hematocrit (Hct) and red blood cell (RBC) rigidity were assessed at rest, at the end of exercise and at the 15th, 30th and 60th min of recovery. Exercise increased gb, gp and Hct above resting values in both groups and these parameters remained higher until the 15th or 30th min of recovery as compared to resting values. RBC rigidity was unchanged from baseline values in both groups during exercise and recovery. No difference was observed between the two groups for gp and Hct but gb and RBC rigidity were higher in the SCT carriers at every time point compared with the control group. The higher RBC rigidity and gb found in SCT carriers at rest and in response to a brief supramaximal exercise might constitute a risk factor for microcirculatory complications. Indeed, a short supramaximal exercise test may not be completely inoffensive for SCT carriers.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00706158
https://hal.univ-antilles.fr/hal-00706158
DOI : 10.1007/s00421-006-0155-3

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
This study tested the hypothesis that trained sickle cell trait (SCT) carriers are not subjected to greater risk of rhabdomyolysis or renal failure in response to moderate submaximal exercise than subjects with normal hemoglobin (CONT). Blood markers in 11 trained SCT carriers and 12 control counterparts were measured before and after 40 min of exercise at 55% of peak power output (Ppeak) conducted in thermoneutral environment. Body weights decreased with exercise in the same proportion in the two groups (from 65.1 ± 7.0 kg to 64.1 ± 7.0 kg and from 70.2 ± 6.6 to 68.6 ± 6.6 kg at the end of exercise in SCT and CONT, respectively). Heart rate and rectal temperature increased in the two groups in response to exercise, but the groups remained closely matched. Serum urea, CRP, CK and LDH were similar in the two groups and remained unchanged in response to exercise. Creatinine, Na + , K + , Cl − and myoglobin concentrations increased above baseline in response to exercise, with changes of the same magnitude in the two groups. In summary, the results of the present study suggest that moderate submaximal exercise is not unsafe from a biochemical point of view for sportsmen carrying SCT.
ISSN: 1386-0291

hal-01163943
https://hal.univ-antilles.fr/hal-01163943
DOI : 10.3233/CH-2011-1524

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
An inter-laboratory exercise was organized under the PHARMAS EU project, by the Advanced School of Public Health (EHESP), in order to evaluate the performances of analytical methods for the measurement of antibiotics in waters (surface and tap). This is the first time such an exercise on antibiotics has been organized in Europe, using different kinds of analytical methods and devices. In this exercise thirteen laboratories from five countries (Canada, France, Italy, the Netherlands and Portugal) participated, and a total number of 78 samples were distributed. During the exercise, 2 testing samples (3 bottles of each) prepared from tap water and river water, respectively, spiked with antibiotics, were sent to participants and analyzed over a period of one month. A final number of 77 (98.7%) testing samples were considered. Depending on substances studied by each participant, 305 values in duplicate were collected, with the results for each sample being expressed as the target concentration. A statistical study was initiated using 611 results. The mean value, standard deviation, coefficient of variation, standard uncertainty of the mean, median, the minimum and maximum values of each series as well as the 95% confidence interval were obtained from each participant laboratory. In this exercise, 36 results (6% of accounted values) were outliers according to the distribution over the median (box plot). The outlier results were excluded. In order to establish the stability of testing samples in the course of the exercise, differences between variances obtained for every type of sample at different intervals were evaluated. The results showed no representative variations and it can be considered that all samples were stable during the exercise. The goals of this inter-laboratory study were to assess results variability when analysis is conducted by different laboratories, to evaluate the influence of different matrix samples, and to determine the rate at which participating laboratories successfully completed the tests initiated.
Talanta

hal-00878118
https://hal.archives-ouvertes.fr/hal-00878118
DOI : 10.1016/j.talanta.2012.06.064
PUBMED : 22939142

Éditeur(s) : HAL CCSD Thieme Publishing
Résumé : International audience
The aim of the present study was to compare the effects of prior cycling and a successive run on respiratory muscle performance during a cycle-run succession as performed in the triathlon. We hypothesized that despite the moderate intensity of exercise and the absence of exhaustion, the crouched cycling position would induce a decrease in respiratory muscle performance that would be reversed by the successive vertical run position. Ten male triathletes (22.6 +/- 1.1 yr) performed a four-trial protocol: (1) an incremental cycle test to assess maximal oxygen uptake (VO2max), (2) 20 min of cycling (C), (3) 20 min of running (R), and (4) 20 min of cycling followed by 20 min of running (C-R). Trials 2, 3 and 4 were performed at the same metabolic intensity, i. e., 75 % of VO2max. Respiratory muscle force was assessed by measuring maximal expiratory (P(Emax)) and inspiratory (P(Imax)) pressures from the functional residual capacity (FRC) before and 10 min after C, R, and C-R. Respiratory muscle endurance was assessed one day before and 30 min after C, R, and C-R, by measuring the time limit (T(lim)), which corresponds to the length of time a respiratory load can be sustained before the process of fatigue develops sufficiently to cause task failure. The results showed a similar significant decrease in P(Imax) (132.4 +/- 4.9 versus 125.7 +/- 5.6 cm H2O, p < 0.05) and T(lim) (5.22 +/- 0.28 versus 3.68 +/- 0.32 min, p < 0.05) post-C and post-C-R (133.7 +/- 4.0 versus 126.9 +/- 5.2 cm H2O, and 5.29 +/- 0.18 versus 3.49 +/- 0.41 min, respectively, p < 0.05) compared with the pre-trial values. In contrast, P(Imax) and T(lim) were not significantly decreased post-R (131.8 +/- 6.1 cm H2O versus 129.6 +/- 6.4 cm H2O, and 4.90 +/- 0.69 versus 4.40 +/- 0.56 min, respectively, p > 0.05). We concluded that moderate intensity exercise not performed to exhaustion induced a decrease in respiratory muscle performance. Moreover, the respiratory muscle fatigue induced by prior cycling was maintained, and neither reversed nor worsened, by the successive run.
ISSN: 0172-4622

hal-00720715
https://hal.univ-antilles.fr/hal-00720715

Éditeur(s) : HAL CCSD Human Kinetics
Résumé : International audience
In order to study the acclimatization process over 14 days of exposure to tropical climate, 9 triathletes performed 4 outdoor indirect continuous multistage tests in both thermoneutral and tropical conditions. The thermoneutral test (TN, 14 C, 45% rh) was performed before traveling to the tropical area (Martinique, FWI). The tropical tests were performed 2, 8, and 14 days after arrival (32.9 C, 78% rh). During each trial, we measured tympanic temperature, sweat rate, body mass loss, heart rate (HR), and performance. The results showed that 1) the mean tympanic temperature was greater in T2 (P < .001), T8 (P < .01) and T14 (P < .01) than in TN and significantly lower in T14 than in T2 (P < .05); 2) the mean sweat rate was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 3) the body mass loss after trials was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 4) the mean HR and HR at rest were significantly higher (P < .005) in T2 than in TN, T8, T14 and the mean HR was significantly lower (P < .05) in T14 than in the other trials; and 5) the performance time was significantly lower in T2 (P < 0.02), T8 (P < 0.03) and T14 (P < 0.05) than in TN. We concluded that 14 days of exposure.
ISSN: 1066-7814

hal-00720075
https://hal.univ-antilles.fr/hal-00720075
https://hal.univ-antilles.fr/hal-00720075/document
https://hal.univ-antilles.fr/hal-00720075/file/02.Voltaire_551_.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Growth hormone (GH) may stimulate water loss during exercise by activating sweating. This study investigated GH secretion and water loss during sequential cycling and running, taking postural changes into account. The two exercise segments had similar durations and were performed at the same relative intensity to determine their respective contributions to water loss and the plasma volume variation noted in such trials. Eight elite triathletes first performed an incremental cycle test to assess maximal oxygen consumption. Then, the triathletes performed one of two trials in randomized order: constant submaximal cycling followed by treadmill running (C 1 –R 2) or an inversed succession of running followed by cycling (R 1 –C 2). Each segment of both trials was performed for 20 minutes at ,75% of maximal oxygen consumption. The second trial, reversing the segment order of the first trial, took place two weeks later. During cycling, the triathletes used their own bicycles equipped with a profiled handlebar. Blood sampling (for GH concentrations, plasma viscosity and plasma volume variation) was conducted at rest and after each segment while water loss was estimated from the post-and pre-measures. GH increases were significantly lower in R 2 than C 2 (72.2650.1 vs. 164.06157 ng.ml 21 .min 21 , respectively; P,0.05). Water loss was significantly lower after C 1 –R 2 than R 1 –C 2 (11056163 and 12356153 ml, respectively; P,0.05). Plasma volume variation was significantly negative in C 1 and R 1 (26.1562.0 and 23.1665.0%, respectively; P,0.05), not significant in C 2 , and significantly positive for seven subjects in R 2 (4.0563.1%). We concluded that the lower GH increases in R 2 may have contributed to the smaller reduction in plasma volume by reducing sweating. Moreover, this lower GH response could be explained by the postural change during the transition from cycling to running. We recommend to pay particular attention to their hydration status during R 1 which could limit a potential dehydration during C 2 .
ISSN: 1932-6203

hal-01136734
https://hal.univ-antilles.fr/hal-01136734
https://hal.univ-antilles.fr/hal-01136734/document
https://hal.univ-antilles.fr/hal-01136734/file/Galy%20et%20al.%20-%202014%20-%20Sequential%20exercise%20in%20triathletes%20Variations%20in%20GH%20and%20water%20loss.pdf
DOI : 10.1371/journal.pone.0096145

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Strenuous exercise is associated with an inflammatory response involving the activation of several types of blood cells. In order to document the specific activation of these cell types, we studied the effect of three maximal exercise tests conducted to exhaustion on the quantitative and qualitative pattern of circulating cell-derived microparticles and inflammatory molecules in healthy subjects. This study mainly indicated that the plasma concentration of microparticles from platelets and polymorphonuclear neutrophils (PMN) was increased immediately after the strenuous exercise. In addition, the increase in plasma concentration of microparticles from PMN and platelets was still observed after 2 hours of recovery. A similar pattern was observed for the IL-6 plasma level. In contrast, no change was observed for either soluble selectins or plasma concentration of microparticles from red blood cells, monocytes and endothelial cells. In agreement, sVCAM-1 and sICAM-1 levels were not changed by the exercise. We conclude that a strenuous exercise is accompanied by platelet-and PMN-derived microparticle production that probably reflects the activation of these two cell types.
ISSN: 1386-0291

hal-01163965
https://hal.univ-antilles.fr/hal-01163965
DOI : 10.3233/CH-2010-1361

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The six-minute walk test is a well-established submaximal exercise reflecting the functional status and the clinical severity of sickle cell patients. The aim of the present cross-sectional study was to investigate the biological determinants of the six-minute walk test performance in children with sickle cell anemia. Hematological and hemorheological parameters, pulmonary function and the six-minute walk test performance were determined in 42 children with sickle cell anemia at steady state. The performance during the six-minute walk test was normalized for age, sex and height and expressed as percentage of the predicted six-minute walk distance. We showed that a high level of anemia, a low fetal hemoglobin expression and low red blood cell deformability were independent predictors of a low six-minute walk test performance. This study describes for the first time the impact of blood rheology in the six-minute walk test performance in children with sickle cell anemia.
ISSN: 1932-6203

inserm-00922110
http://www.hal.inserm.fr/inserm-00922110
http://www.hal.inserm.fr/inserm-00922110/document
http://www.hal.inserm.fr/inserm-00922110/file/2013_Waltz_-_Hematological_and_hemorheological_determinants_6_minutes.pdf
DOI : 10.1371/journal.pone.0077830

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Purpose: The aim of this study was to clarify whether exercising in a tropical climate induces blood rheology alterations despite ad libitum hydration. Methods: Hematological, biochemical and hemorheological changes were investigated in young healthy adults (N = 9 men, 20.7 ± 0.8 yrs) after a 10-km race in hot and humid conditions. Subjects' maximal aerobic abilities were tested using a maximal ramp exercise. Blood was sampled at rest (T R), at the end of the race (T Ex), and after 24 hours of recovery (T 24). Ad libitum hydra-tion was allowed during the race. Blood viscosity (b), red blood cell deformability (EI), aggregation (AI) and disaggregation shear rate (␥) were measured. Results: Hematocrit, hemoglobin and plasma concentration of chlorine, sodium and potassium did not change in response to exercise. No functional consequence was observed on RBC deformability since EI remained unchanged. Percentages of echinocytes, schizocytes and stomatocytes remained in the subclinical range at all times. AI, µ and ßb did not present change. Conclusion: Running exercise in tropical climate with ad libitum hydration does not alter the main rheological properties of blood.
ISSN: 1386-0291

hal-01163975
https://hal.univ-antilles.fr/hal-01163975
DOI : 10.3233/CH-2011-1388