Decrease of physical activity level in adolescents with limb fractures: an accelerometry-based activity monitor study

<p>Abstract</p> <p>Background</p> <p>Immobilization and associated periods of inactivity can cause osteopenia, the physiological response of the bone to disuse. Mechanical loading plays an essential role in maintaining bone integrity. Skeletal fractures represent one cause of reduction of the physical activity (PA) level in adolescents. The purpose of this study was to quantify the reduction of PA in adolescents with limb fractures during the cast immobilization period compared with healthy controls.</p> <p>Methods</p> <p>Two hundred twenty adolescents were divided into three groups: those with upper limb fractures (50 cases); lower limb fractures (50 cases); and healthy cases (120 cases). Patients and their healthy peers were matched for gender, age, and seasonal assessment of PA. PA level was assessed during cast immobilization by accelerometer. Time spent in PA in each of the different intensity levels - sedentary, light, moderate, and vigorous - was determined for each participant and expressed in minutes and as a percentage of total valid time.</p> <p>Results</p> <p>Reduction in PA during cast immobilization was statistically significant in patients with limb fractures compared to healthy controls. The total PA count (total number of counts/min) was significantly lower in those with upper and lower limb fractures (-30.1% and -62.4%, respectively) compared with healthy controls (p < 0.0001 and p = 0.0003, respectively). Time spent in moderate-to-vigorous PA by patients with upper and lower limb injuries decreased by 36.9% (<it>p </it>= 0.0003) and 76.6% (<it>p </it>< 0.0001), respectively, and vigorous PA was reduced by 41.4% (<it>p </it>= 0.0008) and 84.4% (<it>p </it>< 0.0001), respectively.</p> <p>Conclusions</p> <p>PA measured by accelerometer is a useful and valid tool to assess the decrease of PA level in adolescents with limb fractures. As cast immobilization and reduced PA are known to induce bone mineral loss, this study provides important information to quantify the decrease of skeletal loading in this patient population. The observed reduction of high intensity skeletal loading due to the decrease in vigorous PA may explain osteopenia due to disuse, and these data should be kept in mind by trauma practitioners to avoid any unnecessary prolongation of the cast immobilization period.</p

Appreciation de la qualite d'un kit commercial pour la détection sérologique de Mycosphaerella pinodes

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Condition physique et capacité respiratoire mitochondriale dans le muscle squelettique de cheval

We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0–2.5 mg) permeabilized muscle fibres sampled from triceps brachii of healthy horses. The present investigation on horse skeletal muscle has tested the methodology used to study mitochondrial function in muscle microbiopsies by high-resolution respirometry to define reference protocols for horses (from sampling procedure to data analysis).Nous avons appliqué la respirométrie à haute résolution et mis au point des protocoles de titration pour étudier la physiologie mitochondriale dans des microbiopsies musculaires prélevées au niveau du triceps brachial de chevaux sains. Ces études ont pour objet de valider la méthodologie et de définir des protocoles de référence pour les chevaux