Exercise is a relatively inexpensive way to improve the health and quality of life of patients on dialysis. And the results are well worth the effort, argues clinical scientist in the Renal Unit at the Lister Hospital, Stevenage, Chiew Kong.

Unlike cardiac and stroke patients, those with renal failure and on dialysis have somehow had their long-term rehabilitation overlooked.

Even when well dialysed, thanks to advances in technology and know-how, many are unfit (1-6) and, as a result, have a poor quality of life.

We dialyse them well but we do not make them fit!

Exercise tolerance in end-stage renal failure is reduced owing to proximal muscle weakness compounded by co-morbidity factors. As well as the more conventional predictors of protein-catabolic rate and the delivered Kt/V, a poor score on physical activity has been shown to predict mortality and need for hospitalisation (7,8).

Yet, there is ample evidence that, with regular exercise, physical fitness improves (9-12).

With the advent of rhu-erythropoeitin, patients should be able to do more physically but, unfortunately, this is not always the case. The benefit of rhu-erythropoeitin is not realised in some cases and, in many, it is not maximised. They continue on a downward spiral to physical incapacity, even long before dialysis is needed (6).

		Can we intervene here?
		Can we prevent it?

I believe we can, and should!

Benefits of exercise
The abnormal histological changes in muscle that have been associated with muscle wasting in renal failure are non specific (5) and the good news is that they are reversible with exercise training (13). This suggests that disuse is the cause of the abnormality.

But data on the improvement in exercise capacity with regular exercise sometimes do not tell the whole story. This is often accompanied by improved self-esteem experienced by patients as a result of their taking ownership of their health for a change.

Anecdotal evidence abound on the benefits experienced by such patients.

One 78-year-old gentleman could initially only swim three lengths of the pool. Six weeks later he was able to swim 20 lengths. Not only did he feel fitter and stronger, he also got rid of his depression.

A 67-year-old lady surprised the staff and fellow patients one morning when she triumphantly walked from her transport to her dialysis couch instead of using her wheelchair.

The physical improvements bring with them other benefits, like better blood pressure and plasma-lipid control (12), sleeping and eating better.

		These are good enough reasons for intervening.
		So why are not more patients exercising?

Encouragement from the medical and nursing staff is vital in promoting this evidence-based practice. There are obstacles to overcome, such as ignorance, lack of motivation and the "sick role" that some patients cling to. Time is another problem, especially for the haemodialysis patients.

Exercise during dialysis
A perfect solution to compliance and a constructive use of dialysis time is to cycle during dialysis. It is both safe from the point of view of exercise-induced efflux of potassium on top of raised levels, and feasible in term of practicality (14,15).

In addition to the improvement in exercise tolerance, the efficiency of dialysis is enhanced (16) after one hour of exercise. This is owing to increased perfusion allowing a greater exchange of solutes to take place in the exercising muscles, thus resulting in a significantly smaller rebound of urea and creatinine.

More importantly, patients get a great sense of well being after dialysis. This "feel good" factor is not easy to measure and one can only go by what patients report.

The other benefits of cycling are the prevention of cramps and the control of the "restless-leg syndrome" which can make dialysis a nightmare.

The duration of exercise depends on the individual. Patients are advised to start slowly and then build up their time gradually. Many of them tend to cycle for from one hour to the full duration of dialysis. It is more like a marathon than a sprint, with rest in between.

Contra-indications to exercise
Apart from angina on exertion, musculo-skeletal problems and assuming the haemoglobin concentration is reasonable, there are few reasons not to exercise providing the patients are sensible about it and do not push themselves too hard.

"No pain, no gain" does not apply here!

In my experience, diabetic and blind patients are equally eligible and have been successful in cycling regularly, both during and between dialysis. There is no age limit for exercise. But cycling during dialysis unfortunately excludes patients with femoral lines.

Prevention of physical weakness
Physical weakness has been accepted as a natural sequel to renal failure.

This need not be the case it might be prevented by early intervention with exercise training begun well before dialysis is needed, haemoglobin concentration permitting. There are no studies to support this yet but given the evidence of physical and histological improvements I am convinced that it can be achieved. The walking-sticks and wheelchairs associated with renal failure could become a thing of the past.