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. DESIGN: 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.

Resistance training improves strength and functional measures in patients with end-stage renal disease.

BACKGROUND: The current study was designed to examine the effect of 12 weeks of resistance training on strength and functional ability in 10 medically stable hemodialysis patients (age, 42.8 +/- 4.4 years). METHODS: Subjects were tested on four separate occasions, each separated by 6 weeks. The first (T1) and second tests (T2) were controls with no exercise intervention between them. T3 followed 6 weeks of resistance training, and T4 occurred after 12 weeks of training. Variables tested included percentage of body fat, distance covered in the 6-minute walk test, peak torque of quadriceps muscles of the dominant leg, maximal handgrip strength, normal and maximal walking speeds, and time to complete 10 repetitions of the sit-to-stand-to-sit test. Data were analyzed by means of a one-way repeated-measures analysis of variance procedure. RESULTS: Results indicate that after 12 weeks of training, there was a significant (P < 0.05) increase (12.7%) in peak torque at 90 degrees /s (139.1 +/- 19.3 nm) compared with T1 and T2 (mean, 124.1 +/- 18.7 [SEM]; 123.5 +/- 16.9 Nm), respectively. The distance covered during the 6-minute walk was increased ( approximately 5%; P < 0.05) compared with baseline (T1, 522.1 +/- 46.2 m; 521.9 +/- 48.5 m) after 6 weeks of training (548.3 +/- 52.1 m) and remained elevated at week 12 (546.5 +/- 54.2 m). Maximal walking speed was increased (P < 0.05) by week 12 (195.9 +/- 15.4 cm/s) compared with baseline (T1, 182.9 +/- 12.7; 185.5 +/- 13.0 cm/s). Time to complete 10 repetitions of the sit-to-stand-to-sit test decreased at 12 weeks (17.8 +/- 1.9 seconds) versus baseline (T1, 20.3 +/- 1.5 seconds; T2, 20.6 +/- 5.5 seconds). CONCLUSION: Resistance training can be used safely to increase strength and functional capacity in stable hemodialysis patients.