A randomized trial of aerobic exercise in chronic kidney disease: Evidence for blunted cardiopulmonary adaptations.

Background: Patients with chronic kidney disease have reduced cardiorespiratory fitness levels that contribute to mortality.

Objectives: The purpose of this study was to investigate the effects of aerobic exercise on cardiopulmonary function in patients with chronic kidney disease.

Methods: A total of 36 patients (mean [SD] estimated glomerular filtration rate 44 [12] ml/min/1.73m) were randomly allocated to an exercise training or a control arm over 12 weeks. The exercise training group performed aerobic exercise for 45min 3 times/week at 65% to 80% heart rate reserve. The control group received routine care. Outcome measures were assessed at baseline and 12 weeks. Cardiopulmonary exercise testing was performed on a cycle ergometer with workload increased by 15W/min. A battery of physical function tests were administered. Habitual physical activity levels were recorded via accelerometry. Data are mean [SD].

Results: Exercise training improved VO as compared with the control group (exercise: 17.89 [4.18] vs 19.98 [5.49]; control: 18.29 [6.49] vs 17.36 [5.99] ml/kg/min; P<0.01). Relative O pulse improved following exercise, suggestive of improved left ventricular function (exercise: 0.12 [0.02] vs 0.14 [0.04]; control: 0.14 [0.05] vs 0.14 [0.04] ml/beat/kg; P=0.03). Ventilation perfusion mismatching (V/VCO2) remained evident after exercise (exercise: 32 [5] vs 33 [5]; control: 32 [7] vs 34 [5] AU; P=0.1). Exercise did not affect the ventilatory cost of oxygen uptake (V/VO; exercise: 40 [7] vs 42 [8]; control: 3 [7] vs 41 [8] AU; P=0.5) and had no effect on autonomic function assessed by maximal and recovery heart rates. We found no changes in physical function or habitual physical activity levels.

Conclusions: Cardiopulmonary adaptations appeared to be attenuated in patients with chronic kidney disease and were not fully restored to levels observed in healthy individuals. Improvements in exercise capacity did not confer benefits to physical function. Interventions coupled with exercise may be required to enhance adaptations in chronic kidney disease. Performed according to CONSORT guidelines; ClinicalTrials.gov: NCT02050035.