Does chronic exercise attenuate age-related physiological decline in males?
- Authors: Hayes, Lawrence , Grace, Fergal , Sculthorpe, Nicholas , Herbert, Peter , Kilduff, Liam , Baker, Julien
- Date: 2013
- Type: Text , Journal article
- Relation: Research in Sports Medicine Vol. 21, no. 4 (2013), p. 343-354
- Full Text: false
- Reviewed:
- Description: Alteration in body composition, physical function, and substrate metabolism occur with advancing age. These changes can be attenuated by exercise. This study evaluated whether master athletes (MA [n = 20]) would have improved exercise capabilities, anthropometry, and hormone profiles when compared with age-matched sedentary counterparts (S [n = 28]). The MA group was predominantly aerobically trained with some resistance exercise incorporated in their routine. The VO(2max), peak power output, and salivary testosterone was significantly higher (p < 0.05) in the MA group, while diastolic blood pressure, systolic blood pressure, and body fat percentage were lower (p < 0.05). Cortisol, fat free mass, (FFM) and total body mass were not significantly different between groups. Salivary testosterone correlated positively with VO(2max) (r(2) = .320), suggesting that increased aerobic capacity is linked with higher concentrations of testosterone. These results suggest that life-long exercise is associated with favorable body composition and attenuation of the age related decline in testosterone.
Androgens affect myogenesis in vitro and increase local IGF-1 expression
- Authors: Sculthorpe, Nicholas , Solomon, Andrew M , Sinanan, Andrea C M , Bouloux, Pierre-Marc G , Grace, Fergal , Lewis, Mark
- Date: 2012
- Type: Text , Journal article
- Relation: Medicine and Science in Sports and Exercise Vol. 44, no. 4 (2012), p. 610-615
- Full Text: false
- Reviewed:
- Description: PURPOSE: The mechanism whereby anabolic androgens are associated with hypertrophy of skeletal muscle is incompletely understood but may involve an interaction with locally generated insulin-like growth factor (IGF) 1. The present investigation utilized a cell culture model of human skeletal muscle-derived cell maturation to test the hypothesis that androgens increase differentiation of human muscle precursor cells in vitro and to assess effects of androgen with or without IGF-1 on IGF-1 messenger RNA (mRNA) expression in human muscle precursor cells. METHODS: Differentiation of muscle-derived cells was induced under standard low-serum conditions. Cultures were then exposed to androgen (testosterone (T)) at 50, 100, and 500 nM or IGF-1 (10-50 ng.mL(-)(1)). Immunocytochemistry and real-time polymerase chain reaction (RT-PCR) were used to assess effects of androgens and IGF-1 after 3- (early) or 7-d (late) muscle differentiation, respectively; RT-PCR was used to quantify the effects on androgen receptor expression. RESULTS: Under low-serum conditions, 3-d exposure to androgens or IGF-1 or both resulted in no significant increase in cellular myogenic commitment. After 7-d exposure, however, T and IGF-1 were both found to increase fusion index with no observable synergistic effect. T also increased IGF-1 mRNA generation (P < 0.0001), whereas exogenous IGF-1 (P < 0.001) reduced IGF-1 mRNA transcription relative to control. The T effect was reversible after treatment with flutamide, an androgen receptor antagonist. CONCLUSIONS: Both T and IGF-1 increase myogenic commitment after 7-d exposure to a differentiation medium. With T causing a concomitant increase in IGF-1 mRNA underpinning IGF-1 as a central mediator in the cellular pathways associated with muscle hypertrophy, including those affected by androgens. The novel system described has the potential for elucidating the pattern of growth factor effects associated with androgens in skeletal muscle.