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 Public Library of Science
Résumé : International audience
BACKGROUND/AIM: Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue. METHODS: We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients. RESULTS: Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects. CONCLUSIONS: Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit mitochondrial respiration but increases muscle microvascular blood flow.
ISSN: 1932-6203

inserm-00849035
http://www.hal.inserm.fr/inserm-00849035
http://www.hal.inserm.fr/inserm-00849035/document
http://www.hal.inserm.fr/inserm-00849035/file/2013_Waltz_-_Normal_muscle_oxygen_consumption_and_fatigability_in_sickle_cell_patients.pdf
DOI : 10.1371/journal.pone.0052471

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-01622938
https://hal-umontpellier.archives-ouvertes.fr/hal-01622938
DOI : 10.1055/s-2003-37201
PUBMED : 12582954