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Title: Effects of testosterone, lifelong physical activity and resistive exercise on skeletal muscle structure and function in older males
Author: Atkinson, Ross Alexander
ISNI:       0000 0004 2721 608X
Awarding Body: Manchester Metropolitan University
Current Institution: Manchester Metropolitan University
Date of Award: 2012
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Ageing is associated with a reduction in skeletal muscle mass (sarcopenia) which impacts on musculoskeletal health (Rosenberg 1997) and affects even successfully ageing adults (Roubenoff 2002). The causes of sarcopenia include reduced neural drive, decreased physical activity levels, poor nutrition and alterations in immunological and hormonal status (Narici and Maffulli 2010). Frailty is a clinical syndrome also associated with several age-related conditions, reduced muscle strength, disability and death (Fried, Tangen et al. 2001). The burden placed upon the health service by those suffering from the combined effects of these conditions is substantial, and therefore ways to prevent age-related deteriorations in musculoskeletal health are clearly warranted. Previously it has been shown that testosterone (T) plays an important role in skeletal muscle development and regulation, and reductions in this hormone have been identified as a major factor contributing to the development of sarcopenia (Ianuzzi-Sucich, Prestwood et al. 2002). Resistance training (RT), however, is the main promoter of skeletal muscle hypertrophy, and is effective in older adults as well as in the young (Fiatarone, Marks et al. 1990). While it is clear that there is a close relationship between muscle mass, strength and T, the variation in each of these parameters in ageing individuals with differing levels of physical activity is less well known. The present work therefore aims to address some of these aspects. Cross-sectional data from this thesis suggest that T does indeed have a positive effect on skeletal muscle mass and strength. T is also an important regulator of BMI. This work also shows that while muscle mass and strength may not be markedly altered in men with low T levels at older age, physiological T replacement does promote preservation of muscle mass in men with low to borderline low T. Despite this, it is unclear whether a marked increase in strength follows. Continued high levels of physical activity into older age (chronic exercise) may be associated with modest maintenance of circulating T levels, but without substantial benefits to muscle size and strength. It is evident from this work, however, that periodised RT regimes in older men may have beneficial effects on circulating T, muscle mass and strength. It is envisaged that future therapies aimed at offsetting the effects of muscle wasting could involve a combination of androgen treatment and resistance exercise.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available