Résumé :
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Sarcopenia is a scientific term indicating the physiological reduction of skeletal muscle mass and strength in older people. Sarcopenia has a multifactorial origin linked to: oxidative damage of fibers (Fulle et al, Exp. Gerontol 40:189, 2005), mitochondrial damage (Brunk UT et al, Eur J Biochem, 269(8):1996-2002, 2002) reduced levels of GH, IGF-1, steroids and reduced myogenesis (Beccafico et al., ANNALS 1100:345-352, 2007). The physical activity is able to slow down and/or revert this condition (Taaffe DR et al, Clin Physiol 16:381- 391, 1996). We analysed the effects of three different physical activity programs (endurance training, resistance training and local vibrational energy) on vastus lateralis biopsy derived by 65-85 years old people, before and after the training. From these muscle fragments we analysed: (i) the specific tension development of single fibers and the expression of myosin heavy chain proteins; (ii) the transcriptional profile and (iii) the regenerative capacity of satellite cells. The single fiber strength development do not change with any training protocol. Considering the gene expression profiles, each physical activity share a stimulation of a specific metabolic pathway; both endurance and vibrational training increase the aerobic metabolism while the resistance training stimulates the creatine metabolism. All the training, in a different manner, stimulate the expression of sarcomeric and cytoskeletal proteins and in particular the vibrational training stimulates proteins linked to Z-line. Moreover, the endurance training induces the expression of protein for neuronal chemotaxis. We studied also the behavior of satellite stem cells after the specific training and their contribution to regeneration process and fiber trophism. In conclusion, our results suggest that all our training counteract Sarcopenia progression and each of them are able to stimulate a specific molecular signaling. The effects are specific because it exists coherence between exercise typology and stimulated metabolism.
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