Exercise as adjunctive therapy in chronic kidney disease

Background. Exercise is a natural medicine that has been prescribed for the prevention and management of chronic diseases, to enhance quality of life, improve health status and promote longevity. Current efforts to implement exercise as routine practice in the conventional renal replacement therapy population have been hampered by a lack of randomised controlled data. The aim of this thesis was to investigate the effect of exercise as an adjunctive therapy to enhance outcomes pertaining to renal transplantation, vascular access, haemodialysis adequacy and muscle wasting in Stages four and five Chronic Kidney Disease patients. It was hypothesised that randomised controlled trials employing gold standard outcome measures would reveal significant beneficial effects of exercise that are strongly associated with quality of life, hospitalisation and survival in this patient population. Reports. The first report presents a systematic literature review of exercise in the kidney transplant population. The largest positive effects were noted on intermediate outcomes such as aerobic fitness and muscle strength. Presumably these adaptations contributed to the trends observed for improvement in quality of life. Whether exercise impacts on outcomes associated with longevity of life requires further study. The rest of the thesis focused on patients receiving the more popular form of renal replacement therapy, haemodialysis. The first empirical study of the thesis appertaining to vascular access investigated the feasibility of implementing a post-operative forearm exercise intervention for arteriovenous fistula maturation. Exercise had no effect on primary outcomes measures of arterial diameter (95% CI, -0.24 [-1.12; 0.51] mm) and venous diameter (95% CI, 0.16 [-1.84; 1.24] mm). It was concluded that future randomized controlled trials should investigate a similar protocol implemented before arteriovenous fistula creation to enhance surgery success and maturation. The second randomised controlled trial explored the effect of intradialytic exercise in comparison to the traditional prescription of increased dialysis time to enhance dialysis adequacy and solute removal. Increased haemodialysis time, but not exercise, increased equilibrated Kt/Vurea compared to control trials (Extra time vs. control: 95% CI, 0.15 [0.05; 0.26]; exercise vs. control: 95% CI, 0.03 [-0.05; 0.12]). Exercise, but not increased time, increased phosphate reduction ratio (exercise vs. control: 95% CI, 8.6 [0.5; 16.7] %; extra time vs. control: 95% CI, 5.0 [-1.0; 11.1] %). Thus intradialytic exercise cannot replace the traditional prescription of increased haemodialysis time, but may be a useful adjunctive therapy for serum phosphate control. The third study implemented a randomised controlled trial of intradialytic progressive resistance training for muscle wasting. The primary outcome measure of thigh muscle volume, as measured by magnetic resonance imaging, significantly increased following 12 weeks of training compared to a sham exercise control (95% CI, 193 [63; 324] cm3 ). Intradialytic resistance exercise elicited an anabolic and strength response in haemodialysis patients. However, a surprising lack of a change in functional capacity despite increased muscle mass warrants further investigation. Conclusion. The findings suggested that exercise had a beneficial effect on factors relating to outcomes in Stages 4 and 5 Chronic Kidney Disease patients. However, to ensure effectiveness of interventions and to maximize programme efficiency, careful consideration of basic exercise and physiological principles is required. Nevertheless, the observed benefits of exercising outweighed its risks thus supporting the initiative for exercise prescription as an adjunctive therapy for the management of this disease state.