It is known that chronic kidney disease (CKD) and end-stage kidney disease (ESKD) patients are at an extremely high risk for cardiovascular disease, stroke, and peripheral vascular disease. In addition, most patients have additional risk factors including diabetes, hypertension, and obesity. Should more be done to help improve their risk and overall health? What if clinicians could prescribe an exercise regimen? Are there additional hemodialysis specific benefits to exercising?
In a recent BMC Nephrology publication, Bogataj et al. performed a randomised controlled trial to examines the effects of intradialytic cycling and functional training on dialysis adequacy and other biochemical parameters. Participants were divided into a functional training intervention group (with intradialytic cycling) and an intradialytic cycling only control group. For the first eight weeks, participants in the intervention group performed guided functional exercise training three times a week before each dialysis session and additional intradialytic cycling exercise. This included a warm-up, full range of motion exercises with additional weights, and a cool-down with stretching. For the second eight weeks the same group took the functional training home to do on non-dialysis days. The authors concluded that in both groups the dialysis adequacy improved and was sustained through the entire study; however, additional benefits were found in the intervention group, with promising improvements in the participants’ total cholesterol and low-density lipoprotein (LDL) cholesterol.
The improvement in dialysis adequacy with exercise during hemodialysis is not new. In 2004, Parsons et al. also conducted an eight week study looking at intradialytic exercise and found that there was enhanced dialysate urea removal. The physiology of how improved dialysis adequacy occurs is thought to be through an increase in muscle blood flow and increase in oxygen extraction, which increases capillary surface area and increases the exchange of substances from the tissue to the vascular compartment. This increased diffusion into the vascular compartment allows for substances like urea to be removed by dialysis. Therefore, improved dialysis adequacy. Kong et al. demonstrated a 14% increase in dialysis adequacy from 60 minutes of intradialytic exercise. This increase is equivalent to increasing a dialysis session by 20 minutes. It would be interesting to find out how many of my patients would prefer cycling during dialysis for an hour rather than increasing their dialysis time. Would it be more cost effective to have everyone perform intradialytic exercise rather than increasing dialyzer size or time?
Would it be more cost effective to have everyone perform intradialytic exercise rather than increasing dialyzer size or time?
With the Bogataj et al article, there was also improvement in total cholesterol and LDL for the intervention group. There is clear evidence for preventing major cardiovascular events and mortality with lowering LDL for those with normal or slightly abnormal kidney function. For patients with CKD and ESKD, it can still be controversial. Our guidelines do not advocate starting every ESKD patient on a statin but what about lowering cholesterol with exercise? This type of intervention for cholesterol improvement still needs to be studied over a longer period with examining cardiovascular outcomes.
If budget was not an issue, I might consider purchasing customized cycling equipment for my in-center hemodialysis patients and hiring a kinesiologist or personal trainer to perform rounds in the dialysis unit like our dietician and social worker. With time, I imagine we will have larger, longer duration studies that will further support the idea that a novel exercise prescription strategy has specific health benefits for patients with CKD.