Continuous monitoring and quantification of multiple parameters of daily physical activity in ambulatory Duchenne muscular dystrophy patients.

Multiple motor function and strength assessment tools exist for the evaluation of neuromuscular diseases, but most do not directly assess functional ability in the patients' daily physical activity in their home environment. In this study our aim was to assess: 1) the feasibility and accuracy of physical activity monitoring during two days in a home environment of five DMD patients using a non-commercialized monitor containing a 3D accelerometer and a gyroscope, 2) if a difference in the physical activity parameters could be measured before and one month after starting prednisolone. We reliably quantified the time spend sitting, standing, lying, walking, the number of steps taken, the cadence, the number of walking episodes and their duration as well as how these were distributed over the day. Parameters possibly reflecting endurance, such as the duration of the walking episodes or the succession of two or three walking episodes lasting more than 30 s were the most improved after prednisolone treatment. This degree of detailed determination of physical activity in a home environment has not been previously reported in neuromuscular disorders to our knowledge and some of the reported parameters are potential new outcome measures in clinical trials.

Cross-Cultural Adaptation and Validation of the Spinal Function Sort (SFS) for French- and German-Speaking Patients with Back Complaints

Aim: Functional subjective evaluation through questionnaire is fundamental, but not often realized in patients with back complaints, notably because of lack of validated tools, in accordance with recognized psychometric criteria. The Spinal Function Sort (SFS), developed according to actual standards, was only validated in English. The aim of this study is to translate, adapt and validate the French and German version of the SFS.Method and material: The translation and cross-cultural adaptation were performed following the methodology proposed by the American Association of Orthopedist Surgeon. A total of 344 patients, presenting varied back complaints (especially degenerative and traumatic), took part in this study in a tertiary French- (n=87; mean age 44y; 17 women) and German-speaking (n=257; mean age 41y; 53 women) center. Test-retest reliability was quantified using the intraclass correlation coefficient (ICC) and construct validity was assessed by estimating the Pearson's correlation with the SF-36 physical and mental scales, the Visual Analogue Scale for Pain Intensity (VAS), and subscales of the Hospital Anxiety and Depression Scale (HADS).Results: Respectively for the French and German version, ICC were 0.98 and 0.94. Correlations 0.63 and 0.67 with the SF-36 Physical Functioning subscale; 0.60 and 0.52 with the SF-36 Physical Summary Scale ; -0.33 and -0.51 with the VAS ; -0.08 and 0.25 with the SF-36 Mental Health scale; 0.01 and 0.28 with the SF-36 Mental Summary Scale; -0.26 and -0.42 with the HADS depression; -0.17 and -0.45 with the HADS anxiety.Discussion: For both the French and German version of the SFS, the reliability was excellent. Convergent construct validity with SF-36 physical scales is good, moderated with the VAS. We find out a low correlation with SF-36 mental scales (divergent construct validity). We find out a low correlation with HADS subscales in the French version, and a moderate one in the German version. Selection bias, chronicity of the complaints, as well as cultural differences could explain these results. In conclusion, both the French and German version of the SFS are valid and reliable for evaluation of perceived functional capacity for patients with back complaints.

Alteration of neuromuscular function in squash

The alteration in neuromuscular function of knee extensor muscles was characterised after a squash match in 10 trained players. Maximal voluntary contraction (MVC) and surface EMG activity of vastus lateralis (VL) and vastus medialis (VM) muscles were measured before and immediately after a 1-h squash match. M-wave and twitch contractile properties were analysed following single stimuli. MVC declined (280.5+/-46.8 vs. 233.6+/-35.4 Nm, -16%; P<0.001) after the exercise and this was accompanied by an impairment of central activation, as attested by decline in voluntary activation (76.7+/-10.4 vs. 71.3+/-9.6%, -7%; P<0.05) and raw EMG activity of the two vastii (-17%; P<0.05), whereas RMS/M decrease was lesser (VL: -5%; NS and VM: -12%; P=0.10). In the fatigued state, no significant changes in M-wave amplitude (VL: -9%; VM: -5%) or duration were observed. Following exercise, the single twitch was characterised by lower peak torque (-20%; P<0.001) as well as shorter half-relaxation time (-13%; P<0.001) and reduced maximal rate of twitch tension development (-23%; P<0.001) and relaxation (-17%; P<0.05). A 1-h squash match play caused peripheral fatigue by impairing excitation-contraction coupling, whereas sarcolemmal excitability seems well preserved. Our results also emphasise the role of central activation failure as a possible mechanism contributing to the torque loss observed in knee extensors. Physical conditioners should consider these effects when defining their training programs for squash players.

Effect of aerobic exercise on skeletal muscle mitochondrial content and function in older adults

Regular aerobic exercise training, which is touted as a way to ameliorate metabolic diseases, increases aerobic capacity. Aerobic capacity usually declines with advanced age. The decline in aerobic capacity is typically associated by a decrease in the quality of skeletal muscle. At the molecular level, this decreased quality comes in part from perturbations in skeletal muscle mitochondria. Of particular is a decrease in the total amount of mitochondria that occupy the skeletal muscle volume. What is not well established is if this decrease in mitochondrial content is due to inactive lifestyle or the process of aging. Herein, the work of the thesis shows a clear connection between mitochondrial content and aerobic capacity. This indicates that active individuals with higher VChmax levels also contain higher volumes of mitochondria inside their muscle as opposed to sedentary counterparts who have lower levels of mitochondrial content. Upon taking these previously sedentary individuals and entering them into an aerobic exercise intervention, they are able to recover their mitochondrial content as well as function to similar levels of lifelong athletes of the same age. Furthermore, the results of this thesis show that mitochondrial content and function also correlate with exercise efficiency. If one is more efficient, he/she is able to expend less energy for a similar power output. Furthermore, individuals who increase in efficiency also increase in the ability to oxidize and utilize fat during pro-longed exercise. This increased reliance on fat after the intervention is associated with an increased amount of mitochondria, particularly in the intermyofibrillar region of skeletal muscle. Therefore, elderly adults who were once sedentary were able to recover mitochondrial content and function and are able to reap other health benefits from regular aerobic exercise training. Aging per se does not seem to be the culprit that will lead to metabolic diseases but rather it seems to be a lack of physical activity. -- Un entraînement sportif d'endurance, connu pour réduire le risque de développer des maladies métaboliques, augmente notre capacité aérobie. La capacité aérobie diminue généralement avec l'âge. Ce déclin est typiquement associé d'une diminution de la qualité du muscle squelettique. Au niveau moléculaire, cette diminution est due à des perturbations dans les mitochondries du muscle squelettique,, ce qui conduit à une diminution de la quantité totale des mitochondries présentes dans le muscle squelettique. Il n'a pas encore été établi si cette diminution de la teneur mitochondriale est due à un mode de vie sédentaire ou au processus du vieillissement. Ce travail de thèse montre un lien clair entre le contenu mitochondrial et la capacité aérobie. Il indique que des personnes âgées actives, avec des niveaux de V02max plus élevés, possèdent également un volume plus élevé de mitochondries dans leurs muscles en comparaison à leurs homologues sédentaires. En prenant des individus sédentaires et leur faisant pratiquer une activité physique aérobie, il est possible d'accroître leur contenu de même que leur fonction mitochondriale à des niveaux similaires à ceux d'athlètes du même âge ayant pratiqué une activité physique tout au long de leur vie. De plus, les résultats de ce travail démontrent que le contenu et la fonction mitochondriale sont en corrélation avec l'efficiscience lors d'exercice physique. En agumentant l'effiscience, les personnes sont alors capables de dépenser moins d'énergie pour une puissance d'exercice similaire. Donc, un volume mitochondrial accru dans le muscle squelettique, associé à une fonction mitochondriale améliorée, est associté à une augmentation de l'effiscience. En outre, les personnes qui augmentent leur effiscience, augmentent aussi leur capacité à oxyder les graisses durant l'exercice prolongé. Une augmentation du recours au graisses après l'intervention est associée à une quantité accrue de mitochondries, en particulier dans la région inter-myofibrillaire du muscle squelettique. Par conséquent, les personnes âgées autrefois sédentaires sont en mesure de récupérer leur contenu et leur fonction mitochondriale ainsi que d'autres avantages pour la santé grâce à un entraînement aérobie régulier. Le vieillissement en soi ne semble donc pas être le coupable conduisant aux maladies métaboliques qui semblent plutôt être lié à un manque d'activité physique.