| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Center for the Study of Health Effects of Exercise in Children, University of California, Children's Hospital, College of Medicine, Irvine, California, USA
* To whom correspondence should be addressed. E-mail: dcooper{at}uci.edu.
Circulating insulin-like growth factor-I (IGF-I) is correlated with fitness, but results of prospective exercise training studies have been inconsistent showing both increases and decreases in IGF-I. We hypothesized that energy balance, often not accounted for, is a regulating variable such that training plus an energy intake deficit would cause a reduction in IGF-I while training plus energy intake excess would lead to an increased IGF-I. To test this 19 young healthy men completed a 7-day strenuous exercise program in which they were randomly assigned to either a positive energy balance (overfed, OF, n=10) or negative energy balance (Underfed, UF, n=9) group. IGF-I (free and total), insulin, and IGF binding protein-1 were measured before, during, and one week following the training using ELISA. UF subjects significantly lost while OF subjects significantly gained weight. Free and total IGF-I decreased substantially in the UF group (p<0.0005 for both), but in the OF group IGF-I remained unchanged. The UF group also demonstrated an increase in IGF binding protein-1 (p<0.027) while glucose levels decreased (p<0.0005). In contrast, insulin was reduced in both the OF and UF exercise training groups (p<0.044). Finally, within 7 days of the cessation of the diet and training regimen, IGF-I in the UF group rapidly increased to pre-intervention levels. These data show that energy balance during periods of exercise training substantially and rapidly influences circulating IGF-I and related growth mediators. The data also suggest that exercise associated mechanisms oppose increases in IGF-I early in the course of a training protocol even in overfed subjects.
This article has been cited by other articles:
|
|
 |
|
  S. Khoury-Shakour, S. B. Gruber, F. Lejbkowicz, H. S. Rennert, L. Raskin, M. Pinchev, and G. Rennert Recreational Physical Activity Modifies the Association Between a Common GH1 Polymorphism and Colorectal Cancer Risk Cancer Epidemiol. Biomarkers Prev., December 1, 2008; 17(12): 3314 - 3318. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Alemany, B. C. Nindl, M. D. Kellogg, W. J. Tharion, A. J. Young, and S. J. Montain Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity J Appl Physiol, July 1, 2008; 105(1): 58 - 64. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Venkatasubramanian Antipsychotic-Induced Weight Gain in Patients With Schizophrenia JAMA, April 23, 2008; 299(16): 1899 - 1899. [Full Text] [PDF]
|
|
|
|
|
|
K. R. Rarick, M. A. Pikosky, A. Grediagin, T. J. Smith, E. L. Glickman, J. A. Alemany, J. S. Staab, A. J. Young, and B. C. Nindl Energy flux, more so than energy balance, protein intake, or fitness level, influences insulin-like growth factor-I system responses during 7 days of increased physical activity J Appl Physiol, November 1, 2007; 103(5): 1613 - 1621. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. L. Ahmed, W. Thomas, and K. H. Schmitz Interactions between Insulin, Body Fat, and Insulin-Like Growth Factor Axis Proteins Cancer Epidemiol. Biomarkers Prev., March 1, 2007; 16(3): 593 - 597. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A M M Haydon, R J MacInnis, D R English, H Morris, and G G Giles Physical activity, insulin-like growth factor 1, insulin-like growth factor binding protein 3, and survival from colorectal cancer Gut, May 1, 2006; 55(5): 689 - 694. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M Elloumi, N El Elj, M Zaouali, F Maso, E Filaire, Z Tabka, and G Lac IGFBP-3, a sensitive marker of physical training and overtraining Br. J. Sports Med., September 1, 2005; 39(9): 604 - 610. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. L. Ballard, J. A Clapper, B. L Specker, T. L Binkley, and M. D Vukovich Effect of protein supplementation during a 6-mo strength and conditioning program on insulin-like growth factor I and markers of bone turnover in young adults Am. J. Clinical Nutrition, June 1, 2005; 81(6): 1442 - 1448. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
