IGF-I system responses during 12 weeks of resistance training in end-stage renal disease patients.
OBJECTIVE
To examine the hypothesis that 12 weeks of resistance training would alter circulating concentrations of IGF-I system components in end-stage renal disease (ESRD) patients.


METHODS
Ten ESRD patients underwent 12 weeks of resistance training after a 6 week control period and had morning fasted blood drawn on four occasions (weeks - 6, 0, 6, 12). Immunoassays were performed for serum total and free IGF-I, IGF binding proteins (IGFBPs) 2 and 3, and the acid labile subunit (ALS). Immunoaffinity depletion of ALS-based complexes allowed measurement of non-ternary (i.e., binary) IGF-I and IGFBP-3.


RESULTS
Significant improvements in strength and functional performance were observed. All IGF-I measures were stable during the control period and no changes were observed for the first 6 weeks of resistance training. At week 12, total IGF-I (-15.4+/-28.9%), ternary IGF-I (-16.4+/-36.7%), and the IGF-I/IGFBP-3 ratio had significantly (p < or = 0.05) declined from week 0 values. No changes were observed for free IGF-I, IGFBPs 2 and 3, or the acid labile subunit. The proportion of IGF-I in ternary ( approximately 76.3+/-6.8%), non-ternary ( approximately 22.5+/-6.6%), and free ( approximately 1.2+/-0.5%) forms remained constant throughout the training.


CONCLUSIONS
12 weeks of resistance training in ESRD patients induced a decline in total IGF-I, but did not alter the proportion of IGF-I circulating in free, ternary or non-ternary molecular complexes. The decline in IGF-I occurs in the presence of positive training adaptations on physical performance and we conclude that this response pattern appears to be reflective of favorable neuromuscular anabolic adaptations.
Nindl
Bradley C
BC
Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. bradley.nindl@na.amedd.army.miil
Headley
Samuel A
SA
Tuckow
Alexander P
AP
Pandorf
Clay E
CE
Diamandi
Anastasia
A
Khosravi
M Javad
MJ
Welles
Robert
R
Jones
Margaret
M
Germain
Michael
M
D000328:Adult; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis
D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I