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Theije C.D.,Maastricht University | Costes F.,Service de Physiologie Clinique et de lExercice | Costes F.,Jean Monnet University | Langen R.C.,Maastricht University | And 4 more authors.
Current Opinion in Clinical Nutrition and Metabolic Care | Year: 2011

Purpose of Review: Muscle wasting and impaired muscle oxidative metabolism are common extrapulmonary features of chronic respiratory failure (CRF) that significantly increase disease burden. This review aims to address the question whether hypoxia, an obvious consequence of this disease, actually plays a causal role in these muscle impairments. Recent Findings: In experimental models, a causal role for hypoxia in muscle atrophy and metabolic impairments has clearly been shown. Although the hypoxia-inducible factors and nuclear factor kappa B are putative mediators of these hypoxia-induced alterations, their true involvement remains to be proven. Molecular signatures of disrupted regulation of muscle mass and oxidative metabolism observed in these experimental models also have been shown in muscles of patients suffering from CRF, suggestive of but not conclusive for a causal role of hypoxia. Therapies, including but not restricted to those aimed at alleviating hypoxia, have been shown to partially but not completely restore muscle mass and oxidative capacity in CRF patients, which may imply an additive effect of nutritional modulation of substrate metabolism. Summary: Although hypoxia clearly affects skeletal muscle maintenance, it remains to be confirmed whether and by which underlying molecular mechanisms hypoxia is causally involved in CRF-related muscle atrophy and impaired oxidative capacity. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Costes F.,Service de Physiologie Clinique et de lExercice | Costes F.,Jean Monnet University | Gosker H.,Maastricht University | Feasson L.,Service de Physiologie Clinique et de lExercice | And 6 more authors.
Journal of Applied Physiology | Year: 2015

Exercise training (ExTr) is largely used to improve functional capacity in patients with chronic obstructive pulmonary disease (COPD). However, ExTr only partially restores muscle function in patients with COPD, suggesting that confounding factors may limit the efficiency of ExTr. In the present study, we hypothesized that skeletal muscle adaptations triggered by ExTr could be compromised in hypoxemic patients with COPD. Vastus lateralis muscle biopsies were obtained from patients with COPD who were either normoxemic (n = 15, resting arterial Po2 = 68.5 ±1.5 mmHg) or hypoxemic (n = 8, resting arterial Po2 = 57.0 ± 1.0 mmHg) before and after a 2-mo ExTr program. ExTr induced a significant increase in exercise capacity both in normoxemic and hypoxemic patients with COPD. However, ExTr increased citrate synthase and lactate dehydrogenase enzyme activities only in skeletal muscle of normoxemic patients. Similarly, muscle fiber cross-sectional area and capillary-to-fiber ratio were increased only in patients who were normoxemic. Expression of atrogenes (MuRF1, MAFbx/Atrogin-1) and autophagy-related genes (Beclin, LC3, Bnip, Gabarapl) remained unchanged in both groups. Phosphorylation of Akt (Ser473), GSK-3β (Ser9), and p70S6k (Thr389) was nonsignificantly increased in normoxemic patients in response to ExTr, but it was significantly decreased in hypoxemic patients. We further showed on C2C12 myotubes that hypoxia completely prevented insulin-like growth factor-1-induced phosphorylation of Akt, GSK-3β, and p70S6K. Together, our observations suggest a role for hypoxemia in the adaptive response of skeletal muscle of patients with COPD in an ExTr program. © 2015 the American Physiological Society.

Chiodetti L.,Service de Physiologie Clinique et de lExercice | Coustillas S.,Cabinet Medical | Bouthin B.,Service de Physiologie Clinique et de lExercice | Edouard P.,Service de Physiologie Clinique et de lExercice | Edouard P.,Jean Monnet University
Journal de Traumatologie du Sport | Year: 2015

Purpose: Riding is the first provider of sports spine and spinal cord injuries, before the downhill skiing, rugby, motorcycling and motor racing. Nearly 70% of spinal injuries in sport are the result of an equestrian activity. After the head injury, fractures of the thoracolumbar spine are the most common cause of severe injuries in a riding accident. Among all equestrian disciplines, the cross is by far the most dangerous. Wearing a protective helmet cephalic and thoracic shell on the cross has greatly reduced the number of deaths, but it still remains too serious injuries. In recent years a new protective equipment has been developed, the air bag jacket to improve the prevention of chest and spinal injuries. The objective of this study was to evaluate the effectiveness of wearing the air bag jacket, on reducing the number or severity of chest and spinal injuries in a fall on the cross test. Summary of facts: On the Pompadour National Stud Farm Site, 9 competitions that took place between October 2013 and June 2015 were included in this study involving 2079 runners. Sixty-seven falls were recorded begat 8 serious injuries requiring evacuation including 3 spinal traumas. One rotational horse fall was recorded harmless lesion for its rider who was wearing an airbag jacket. No deaths were recorded. The rate of injury in carrier riders with an air bag jacket was 13.7% against 9% for riders who falls without air bag. Conclusion: Although it is still impossible to say port efficiency air bag jacket, 76% of riders use this additional safety equipment. © 2015.

Celle S.,Service de Physiologie Clinique et de lExercice | Annweiler C.,University of Angers | Annweiler C.,University of Western Ontario | Camicioli R.,University of Alberta | And 3 more authors.
BMC Pulmonary Medicine | Year: 2014

Background: Sleep-related breathing disorders (SRBDs) provoke cognitive and structural brain disorders. Because these disorders have been associated with unsafe gait characterized by an increase in stride-to-stride variability of stride time (STV), we hypothesised that SRBDs could be associated with an increased STV. The aim of this study was to examine the association between SRBDs and STV in French healthy older community-dwellers.Methods: A total of 49 participants (mean age 69.6 ± 0.8years; 65.2% female) were included in this cross-sectional study. All participants, who were free of clinically diagnosed SRBDs before their inclusion, had a nocturnal unattended home-sleep assessment. There were separated in three group based on apnea + hypopnea index (AHI): AHI <15 defining the absence of SRBD, AHI between 15-30 defining mild SRBD, and AHI >30 defining moderate-to-severe SRBD. Coefficient of variation of stride time, which is a measure of STV, was recorded while usual walking using SMTEC® footswitches system. Digit span score was used as a measure of executive performance. Age, gender, body mass index (BMI), number of drugs daily taken, vision, proprioception, history of falls, depression symptoms, global cognitive functioning were also recorded.Results: STV and BMI were higher in participants with mild SRBDs (P = 0.031 and P = 0.020) and moderate-to-severe SRBDs (P = 0.004 and P = 0.002) compared to non-SRBDs. STV positively correlated with AHI (P = 0.036). Lower (i.e., better) STV was associated with the absence of SRBDs (P = 0.021), while greater (i.e., worse) STV was associated with moderate-to-severe SRBD (P < 0.045) but not with mild SRBD (P > 0.06).Conclusion: Our results show a positive association between STV and SRBDs, with moderate-to-severe SRBD being associated with greater gait variability. This association opens new perspectives for understanding gait disorders in older adults with SRBDs and opens the door to treatments options since SRBDs are potential treatable factors. © 2014 Celle et al.; licensee BioMed Central Ltd.

Beauchet O.,University of Angers | Annweiler C.,University of Angers | Annweiler C.,University of Western Ontario | Celle S.,Service de Physiologie Clinique et de lExercice | And 6 more authors.
Brain Topography | Year: 2014

The objectives of this study were to examine the association of stride time variability (STV) with gray and white matter volumes in healthy older adults, and to determine the specific location of any parenchymal loss associated with higher STV. A total of 71 participants (mean age 69.0 ± 0.8 years; 59.7 % female) were included in this study. All participants had a 1.0 Tesla 3D T 1-weighted MRI of the brain to measure gray and white matter volumes. STV was measured at steady-state self-selected walking speed using an electronic footswitch system. We found an association between higher STV and lower gray matter volume in the right parietal lobe (e.g., angular gyrus, Brodmann area 39, cluster corrected pFWE = 0.035). There were no significant associations between STV and higher gray matter volume or change in white matter volume. To the best of our knowledge this study is the first to identify a significant association of higher STV with lower right parietal gray matter volume in healthy older adults. © 2013 Springer Science+Business Media New York.

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