Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Seven male subjects volunteered to participate in an investigation of whether the diurnalincrease in core temperature influences the effects of pre-cooling or passivewarm-up on muscular power. Morning (07:00-09:00 h) and afternoon (17:00-19:00 h) evaluation of maximal power output during a cycling sprint was performed on different days in a control condition (room at 21.8 °C, 69% rh), after 30 min of pre-cooling in a cold bath (16 °C), or after 30 min of passivewarm-up in a hot bath (38 °C). Despite an equivalent increase from morning to afternoon in core temperature in all conditions (+0.4 °C, P < 0.05), power output displayed a diurnalincrease in control condition only. A local cooling or heating of the leg in a neutral environment blunted the diurnal variation in muscular power. Because pre-cooling decreases muscle power, force and velocity irrespective of time-of-day, athletes should strictly avoid any cooling before a sprint exercise. In summary, diurnal variation in muscle power output seems to be more influenced by muscle rather than core temperature.
ISSN: 1440-2440

hal-00706159
https://hal.univ-antilles.fr/hal-00706159
DOI : 10.1016/j.jsams.2007.09.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Second harmonic generation (SHG) microscopy is a powerful tool for studying submicron architecture of muscles tissues. Using this technique, we show that the canonical single frequency sarcomeric SHG intensity pattern (SHG-IP) of premetamorphic xenopus tadpole tail muscles is converted to double frequency (2f) sarcomeric SHG-IP in metamorphic climax stages due to massive physiological muscle proteolysis. This conversion was found to rise from 7% in premetamorphic muscles to about 97% in fragmented muscular apoptotic bodies. Moreover a 66% conversion was also found in non-fragmented metamorphic tail muscles. Also, a strong correlation between predominant 2f sarcomeric SHG-IPs and myofibrillar misalignment is established with electron microscopy. Experimental and theoretical results demonstrate the higher sensitivity and the supra resolution power of SHG microscopy over TPEF to reveal 3D myofibrillar misalignment. From this study, we suggest that 2f sarcomeric SHG-IP could be used as signature of triad defect and disruption of excitation–contraction coupling. As the mechanism of muscle proteolysis is similar to that found in mdx mouse muscles, we further suggest that xenopus tadpole tail resorption at climax stages could be used as an alternative or complementary model of Duchene muscular dystrophy.
ISSN: 1047-8477

hal-01134174
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174/file/Recher%20et%20al_JSB-2015_hal.pdf
DOI : 10.1016/j.jsb.2015.03.003

Éditeur(s) : HAL CCSD Optical Society of America
Résumé : International audience
We present a theoretical simulation of the sarcomeric SHG intensity pattern (SHG-IP) that takes into account myofibrillar misalignment that is experimentally observed in SHG images of proteolysed muscles. The model predicts that myofibrillar displacement results in the conversion from one peak (1P) to two peaks (2P) sarcomeric SHG-IP in agreement with experimental results. This study suggests that sarcomeric SHG-IP is a powerful tool for mapping spatial myofibrillar displacement and its related excitation-contraction disruption that could occur during muscle physiological adaptation and disease.
ISSN: 1094-4087

hal-00820260
https://hal.archives-ouvertes.fr/hal-00820260
https://hal.archives-ouvertes.fr/hal-00820260/document
https://hal.archives-ouvertes.fr/hal-00820260/file/Studysur the_effect-accepted.pdf
DOI : 10.1364/OE.21.011404

Éditeur(s) : HAL CCSD Taylor & Francis (Routledge)
Résumé : International audience
In this study, we analyzed the correlations between hip flexion power, sprint performance, lumbar lordosis (LL) and the cross-sectionalarea (CSA) of the psoas muscle (PM). Ten young adults performed isokinetic tests to determine hip flexion power and two sprinttests. Magnetic resonance imaging was used to determine LL and PM CSA. There were correlations between hip flexion power, sprintperformance, and PM CSA, but LL showed no correlation with any parameter. The impact of hip flexion power and LL on sprintstride pattern efficiency was considered. Hip flexion might not have a simple role in the passive knee replacement of the stride pattern;instead, it may be an active parameter. Other investigations are needed to determine the influence of pelvic architecture on sprintperformance.
ISSN: 0270-1367

hal-01143531
https://hal.univ-antilles.fr/hal-01143531

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