Exercise training improves HR responses and V˙O2peak in predialysis kidney patients.

PURPOSE: The current pilot and feasibility study was designed to examine the effect of 48 wk of moderate-intensity exercise training and dietary modification on kidney function and vascular parameters in chronic kidney disease (CKD) patients. METHODS: Twenty-one stage 2-4 CKD patients (age, 18-70 yr) were randomly assigned to either the training group (TG, n = 10) or the usual care group (n = 11) for 48 wk. The TG received 48 wk of personal training (3 d·wk for up to 55 min per session at 50%-60% V˙O2peak) and dietary counseling, whereas individuals in the usual care group received standard of care and were instructed not to start a structured exercise program while in the study. V˙O2peak, estimated glomerular filtration rate (eGFR), resting and ambulatory HR, plasma lipids (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides), and inflammatory markers (high-sensitivity C-reactive protein and interleukin 6) were assessed at baseline and weeks 24 and 48. An independent group's t-test was used to compare glomerular filtration rate slopes between groups, whereas all other data were analyzed with ANCOVA using the baseline value as the covariate. RESULTS: There were no statistically significant differences in any of the parameters at baseline. The 48-wk intervention led to a significant increase in V˙O2peak, reductions in both resting and ambulatory HR, and increases in LDL cholesterol and in TG, but it had no effect on the rate of change of eGFR over time. CONCLUSIONS: A 48-wk exercise training program, primarily focused on aerobic exercise, increases V˙O2peak and favorably alters autonomic function as evidenced by reductions in HR in stages 2-4 CKD patients. The exercise intervention had no effect on kidney function as assessed by eGFR.

Lack of circulating bioactive and immunoreactive IGF-I changes despite improved fitness in chronic kidney disease patients following 48 weeks of physical training.

OBJECTIVE: As known abnormalities exist in the insulin-like growth factor (IGF) system in chronic kidney disease (CKD) patients, the measurement of bioactive IGF-I may provide further insight into the therapeutic potential of long-term exercise training. DESIGN: Patients (N=21) with stages 3 and 4 CKD were recruited from a local nephrology practice in Springfield, MA and randomized into matched treatment and control groups. The treatment group participated in 48 weeks of supervised, progressive exercise training and dietary counseling, while the control group received only usual care. Treadmill testing, anthropometric measurements, and blood samples for analysis of immunoreactive IGF-I, IGF-II, IGFBP-1 and -2, and bioactive IGF-I were taken at baseline, 24 weeks, and 48 weeks. RESULTS: There were no significant differences in any of the components of the IGF system (all p-values>0.05). Immunoreactive IGF-I levels correlated significantly with bioactive IGF-I at baseline (r=0.50, p=0.02) and at 48 weeks (r=0.64, p=0.01). There was a significant interaction between group and time for both VO(2peak) (p=0.03) and total treadmill time (TT) (p<0.01). CONCLUSIONS: Despite improvements in physical performance, a 48-week training program did not affect any of the circulating IGF system measurements. Disparities between these findings and those of other researchers reporting a biphasic response to long-term training may be explained by differences in study groups and exercise programs.

Immediate blood pressure-lowering effects of aerobic exercise among patients with chronic kidney disease.

AIM: The current study was designed to determine the effect of moderate-intensity aerobic exercise on blood pressure responses within the laboratory for 60 min post exercise and in the subsequent 24 h period in patients with chronic kidney disease. METHODS: Twenty-four subjects with stages 2-4 chronic kidney disease (age = 54.5 +/- 15.2 years, body mass index = 32.0 +/- 5.9 kg/m(2)) on antihypertensive medication completed this study. In random counterbalanced order, subjects were asked to either walk for 40 min at 50-60% VO(2peak) (oxygen consumption) or, on a separate day, to sit quietly in the laboratory for the same length of time. Following exercise or the non-exercise period, blood pressure was taken at 10 min intervals for 60 min. Subjects then wore an ambulatory blood pressure monitor for the next 24 h. RESULTS: Systolic blood pressure (mmHg) was reduced by 6.5 +/- 10.8 compared with the pre-exercise baseline value (130.3 +/- 21.1) in the laboratory after exercise and this was greater than after the control period (0.73 +/- 10.3, P < 0.05). Diastolic blood pressure (mmHg) was reduced following exercise (2.5 +/- 6.4) compared with the control period (2.1 +/- 4.9, P < 0.05). The mean 24 h readings did not differ between exercise or non-exercise days. CONCLUSION: Acute aerobic exercise leads to reduced blood pressure for at least 60 min within the laboratory in chronic kidney disease patients.