PDA

View Full Version : age-related differences in androgen receptor, test, hgh



TPT
07-04-2009, 03:19 PM
the following is a paper by roberts et al. (2009). the experimenters examined outcomes of two groups- young and old men. the outcomes were pre and post exercise of a volume leg workout.

free test was greater of course for the young group pre and post exercise. interestingly, hgh wasnt so different pre and post 24 hours for both groups. but was significantly different 5 min post exercise. so the old group still showed increased in hgh but not as much as the young group. also, the old group showed greater basal gene expression of androgen receptor. thus, a correlation between androgen receptor and pre exercise andro reptor was evident.

so we know that exercise has large anabolic hormonal effects on our muscle development. however, age is a limiting factor and how it may be related to gene expression. we can surely still use drugs like test and hgh.

but what about "changing" some genes to limit our "aging?"




Roberts, MD, Dalbo, VJ, Hassell, SE, and Kerksick, CM. The expression of androgen-regulated genes before and after a resistance exercise bout in younger and older men. J Strength Cond Res 23(4): 1060-1067, 2009-This cross-sectional study examined aging and resistance exercise-related changes in intramuscular gene expression in younger (21.3 +/- 0.6 years, 84.8 +/- 6.0 kg, 26.6 +/- 2.1 kg[middle dot]m-2; n = 11) and older men (67.6 +/- 1.3 years, 88.7 +/- 4.8 kg, 28.6 +/- 1.4 kg[middle dot]m-2; n = 13) surrounding a single bout of resistance exercise. Participants completed 3 x 10 repetitions at 80% of their 1 repetition maximum for Smith squat, leg press, and leg extension. Muscle biopsies were obtained before and 24 hours after exercise, whereas venous blood was collected before, immediately after and 24 hours after exercise. Free testosterone levels were greater in younger participants at all time points (p < 0.05), in addition to a greater increase in the younger men immediately post exercise (p < 0.01). Preexercise human growth hormone levels between age groups were similar (p > 0.05). Human growth hormone increased immediately post exercise in both groups (p < 0.05) with a greater response occurring in the younger (p < 0.001) men. Older men expressed greater levels of androgen receptor (AR) at rest (p = 0.02). A significant correlation existed between preexercise free testosterone levels basal AR gene expression (r = -0.59, p < 0.01). These data suggest that AR expression patterns may be related to circulating free testosterone levels. Although these findings do not fully unveil the genomic effects of androgen signaling and its relationship to muscle wasting conditions, these results provide a platform for future researchers seeking to employ gene therapy to remedy muscle loss.
(C) 2009 National Strength and Conditioning Association

Go to Full Text of this Article (http://forums.rxmuscle.com/nsca-jscr/Fulltext/2009/07000/The_Expression_of_Androgen_Regulated_Genes_Before. 2.aspx)