Aberrant Mitochondrial Homeostasis in the Skeletal Muscle of Sedentary Older Adults

The role of mitochondrial dysfunction and oxidative stress has been extensively characterized in the aetiology of sarcopenia (aging-associated loss of muscle mass) and muscle wasting as a result of muscle disuse. What remains less clear is whether the decline in skeletal muscle mitochondrial oxidative capacity is purely a function of the aging process or if the sedentary lifestyle of older adult subjects has confounded previous reports. The objective of the present study was to investigate if a recreationally active lifestyle in older adults can conserve skeletal muscle strength and functionality, chronic systemic inflammation, mitochondrial biogenesis and oxidative capacity, and cellular antioxidant capacity. To that end, muscle biopsies were taken from the vastus lateralis of young and age-matched recreationally active older and sedentary older men and women (N = 10/group; ♀  =  ♂). We show that a physically active lifestyle is associated with the partial compensatory preservation of mitochondrial biogenesis, and cellular oxidative and antioxidant capacity in skeletal muscle of older adults. Conversely a sedentary lifestyle, associated with osteoarthritis-mediated physical inactivity, is associated with reduced mitochondrial function, dysregulation of cellular redox status and chronic systemic inflammation that renders the skeletal muscle intracellular environment prone to reactive oxygen species-mediated toxicity. We propose that an active lifestyle is an important determinant of quality of life and molecular progression of aging in skeletal muscle of the elderly, and is a viable therapy for attenuating and/or reversing skeletal muscle strength declines and mitochondrial abnormalities associated with aging

Changes in self-reported disability after performance-based tests in obese and non-obese individuals diagnosed with osteoarthritis of the knee

Purpose: The purposes of this study are three-fold: (1) To examine whether the WOMAC questionnaire should be obtained before or after performance-based tests. (2) To assess whether self-reported disability scores before and after performance-based tests differ between obese and non-obese individuals. (3) To observe whether physical activity and BMI predict self-reported disability before and after performance based tests. Methods: A longitudinal study included thirty one participants diagnosed with knee osteoarthritis (OA) using the Kellgren-Lawrence Scale by an orthopedic surgeon. Results: All WOMAC scores were significantly higher after as compared to before the completion of performance-based tests. This pattern of results suggested that the WOMAC questionnaire should be administered to individuals with OA after performance-based tests. The obese OA was significantly different compared to the non-obese OA group on all WOMAC scores. Physical activity and BMI explained a significant proportion of variance of self-reported disability. Conclusion: Obese individuals with knee OA may over-estimate their ability to perform physical activities, and may under-estimate their level of disability compared to non-obese individuals with knee OA. In addition, self-reported physical activity seems to be a strong indicator of disability in individuals with knee OA, particularly for individuals with a sedentary life style