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Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 52, Issue 3 M149-M154, Copyright © 1997 by The Gerontological Society of America
RANDOMIZED CONTROLLED TRIAL |
MV Vitiello, CW Wilkinson, GR Merriam, KE Moe, PN Prinz, DD Ralph, EA Colasurdo and RS Schwartz
Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, USA. [email protected]
BACKGROUND: Lean body mass, strength, and endurance decline with advancing age, changes paralleled by declines in anabolic hormones, including growth hormone (GH) and insulin-like growth factor-I (IGF-I). Acute exercise has been shown to stimulate the GH/IGF-I axis, and long- term exercise increases GH. This study examined the effect of endurance training on IGF-I in healthy older men and women. METHODS: Thirty-one healthy older men (66.9 +/- 1.0 yrs, mean +/- SEM) and 21 healthy older women (67.1 +/- 1.7 yrs) were randomized to either 3d/wk, 6-month endurance (ET3) or stretching/flexibility (SF3) protocols. Another group of 15 healthy older men (69.0 +/- 1.3 yrs) participated in a more intensive 5d/wk, 6-month endurance protocol (ET5). Before and after training, subjects were weight stabilized and participated in maximal exercise tolerance testing, body composition assessment, and fasting blood sampling. RESULTS: ET3 training resulted in a significant increase (14%) in maximal aerobic power (VO2max), significant decreases in body weight (BW), fat mass (FM), and waist/hip ratio (WHR), and a significant increase in fat-free mass (FFM). No significant VO2max or body composition changes were observed in the SF3 group. For the ET5 group, a significant increase (22%) in VO2max and significant decrease in BW, FM, and WHR were observed. No significant changes in IGF-I were observed for any of the three groups. Pre- versus post-training IGF-I values were very stable (r = .86, p < .001) across subjects. CONCLUSIONS: Within-subject basal levels of IGF-I in healthy seniors were extremely stable between pre- and post-training assessments. Two endurance training protocols of magnitudes sufficient to significantly increase aerobic capacity and decrease measures of body adiposity did not significantly increase basal levels of IGF-I in healthy older men and women.
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 M. A.�F. Singh, W. Ding, T. J. Manfredi, G. S. Solares, E. F. O'Neill, K. M. Clements, N. D. Ryan, J. J. Kehayias, R. A. Fielding, and W. J. Evans Insulin-like growth factor I in skeletal muscle after weight-lifting exercise in frail elders Am J Physiol Endocrinol Metab, July 1, 1999; 277(1): E135 - 143. [Abstract] [Full Text]
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