Aerobic Training and Arterial Stiffness in Chronic Kidney Disease (CKD) Patients

The focus of the current research group is to examine the impact of lifestyle interventions on the development of cardiovascular disease (CV) in chronic kidney disease (CKD) patients. The study being proposed is to determine the effect of short-term aerobic training on arterial stiffness and blood pressure (BP) in CKD patients. Arterial stiffness has been chosen as a dependent variable since it is one of the most important predictors of CV complications while hypertension is known to play a critical role both in the development of CV and in the progression of CKD (6, 41). The specific aims of the study are: (a) to determine the effect of short-term aerobic training on arterial stiffness in CKD patients, (b) to determine the effect of short-term aerobic training on resting and ambulatory blood pressures (ABP) in CKD patients and (c) to determine the effect of short-term aerobic training on the acute post-exercise blood pressure response in CKD patients since acute responses may be related to changes following a period of chronic training. Fifty, 35-70 yr old, stage 3 CKD patients, with either diabetes or hypertension as the primary cause of their CKD will be recruited for this study. Subjects will be randomly assigned to either the exercise group (ExG = 25) or to the control group (CG = 25). At the start of the study each subject will attend 4 research sessions. During the first session, resting and 24 hr ABP readings will be recorded. In the second session, anthropometric measures, peak oxygen uptake (VO2peak), and ABP values will be measured. Sessions 3 \& 4 will be performed in random order. During these sessions, pulse wave velocity (PWV), augmentation index (AIx) and BP will be measured at baseline after a rest period. Subjects will then either walk for 30 min at 50-60% of VO2 peak, or sit quietly for an equal period of time. BP will be monitored for 60 min in recovery following exercise and ABP will be taken during the subsequent 24 hrs. ExG will perform supervised aerobic training for 45-50 min, 3 times per week, at a moderate intensity, for 16 weeks. CG will continue their activities of daily living but will not be given an exercise program. All subjects will be retested at week 8 for BP, ABP, and arterial stiffness and at week 16 for all variables. After 16 weeks of the study both groups will be retested using identical procedures as at baseline. A series of 2 X 2 analyses of covariance with age, baseline PWV, AIx and BP as the covariates, will be used to determine the effect of the 16 week intervention period on the primary outcome variables. A 2 X 7 X 2, mixed factorial repeated measures ANOVA will be used to analyze the post-exercise data while a Pearson Moment Correlation Coefficient will be computed to examine the relationship between post-exercise acute responses and BP changes following chronic training. An alpha level of 0.05 will be used for all analyses.