Exercise as it relates to Disease/The Benefits of Regular Walking on Chronic Kidney Disease

This page is a critique of the paper: Kosmadakis, G., John, S., Clapp, E., Viana, J., Smith, A., Bishop, N., et al. (2011). Benefits of regular walking exercise in advanced pre-dialysis chronic kidney disease. 27 (3), 997–1004.

Kidney. Author: Henry Gray (1918) Anatomy of the Human Body

Chronic Kidney Disease

Chronic kidney disease (CKD) is a rapidly growing public health issue estimated to have a prevalence of 8-16% worldwide. CKD is diagnosed when there is the presence of kidney damage or a decrease in kidney function. CKD has various causes, however, is consistently associated with increased morbidity and mortality. Patients with advanced CKD generally suffer from excessive fatigue and weakness, which in turn can lead to decreased physical activity levels and a lower quality of life.

Complications of the disease include

• Increased all-cause and cardiovascular mortality
• Kidney disease progression
• Acute kidney injury
• Cognitive decline
• Anaemia
• Mineral and bone disorders
• Fractures

Together, these factors lead to a progressive downward spiral of deconditioning.

Exercise is recognized as a significant intervention in preventing and rehabilitating many other chronic diseases. However currently, the role of exercise is less well defined in chronic kidney disease. Most previous research on the effects of exercise has concentrated on dialysis patients, with fewer studies on the role of exercise in earlier stages of CKD. Despite this the limited evidence available does suggest exercise is likely to provide benefits to CKD patients, including improved cardiorespiratory fitness, muscle strength, energy intake, and quality of life.

Article Critique

Where is the research from?

The study was conducted in the United Kingdom via a variety of institutions listed below:

• John Walls Renal Unit, University Hospitals of Leicester NHS Trust, Leicester, UK
• School of Graduate Entry Medicine and Health, University of Nottingham, Derby, UK
• Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
• School of Health, Exercise and Biological Sciences, Loughborough University, Loughborough, UK

RPE

6	No exertion at all
7	Very very light
8
9
10
11	Fairly light
12
13	Somewhat hard
14
15	Hard
16
17	Very Hard
18
19	Very very hard
20	Maximum exertion

What kind of research was this?

The investigation design was a prospective comparative study that observed the benefits of regular walking over 6 months on allocated pre-dialysis patients with CKD and compared them with patients who were allocated to continue usual physical activity.

What did the research involve?

The authors followed 40 patients with stage 4 or 5 CKD who were not receiving renal replacement therapy. Patients were allocated to an intervention group and a control group. The exercise intervention group completed individualized exercise programs based on a minimum of 30minutes of walking, 5 times a week for 6 months. The intensity of the exercise was monitored with the Borg Rating of Perceived Exertion scale (RPE) and with a heart rate monitor. Exercise intensity was then adjusted to maintain an RPE between 12 and 14 (somewhat hard) for each session. Participants in the exercise intervention group were asked to record the time and RPE of every exercise session in a diary. The non-exercise control group continued with their usual physical activity, and was not given an exercise program.

Additionally, all forty patients were randomized to receive additional oral bicarbonate supplement or to continue with their usual level of bicarbonate therapy.

What were the basic results?

The results in the exercise intervention group showed:

• Significant improvements in exercise tolerance after both 1 month and 6 months of exercise
• General well-being assessed using the FACIT-Sp questionnaire showed improved scores in domains concerned with physical quality of life and health at one month and maintained at 6 months.
• Improved perception of the impact of the subject's uraemic symptoms. The exercising group reported a decrease in the frequency, intrusiveness and total impact of their symptoms at 1 month and the improvements were maintained at 6months.
• A small but significant reduction in BMI due to decreased fat mass at 1 month, and maintained but not further improved at 6 months. Furthermore, this reduction was mostly seen in exercising patients who also received additional sodium bicarbonate
• That some patients had difficulty in sustaining the exercise regime for the full 6 months, with some beginning to decrease their exercise by the end of the study.

The non-exercise control group showed no changes in exercise tolerance, physical quality of life, perception of the impact of their uraemic symptoms, nor BMI

What conclusions can we take from this research?

This research concludes that there are broad benefits of aerobic physical exercise in patients with CKD. The study provided evidence for the positive effects of walking on exercise tolerance, physical quality of life, uraemic symptoms and BMI. The measurable benefits on the well-being and exercise capacity of patients provides justification to continue to study the benefits of exercise on CKD as well as to prescribe appropriate exercise regimens and to identify strategies to maintain lifestyle changes that promote exercise in the long term for those with CKD. These conclusions are consistent with those of a 2011 Cochrane review, which found significant evidence for the benefits of regular exercise in adults with CKD and concluded that regular exercise for >30minutes a day for 3 sessions a week will improve physical fitness, blood pressure, heart rate and health-related quality of life. More studies including large-scale randomised controlled trials are needed to provide further evidence on the role of physical activity as a CKD intervention, to understand the mechanisms of the benefit of exercise on CKD, to study whether alternate forms of exercise such as resistance exercise will further increase the benefit, and to investigate strategies to promote continued lifestyle changes, to ensure increased habitual daily physical activity levels.⁴

Study limitations

• Patients were not randomized. Generally randomized controlled trials provide better evidence
• Neither therapists nor patients were blinded, which may have led to bias favoring the positive effects of exercise.
• The addition of sodium bicarbonate to the study, may have created a confounding variable to the results of the exercise intervention and the non-exercise control groups.
• Small sample size of only 40 people and may not be indicative of the world population of CKD patients.
• The research relied on patient self-reported exercise, which may have resulted in over-reporting of exercise participation.

Further information/resources

Chronic Kidney Disease Management Handbook: e-copy of the handbook: http://kidney.org.au/cms_uploads/docs/ckd-management-in-gp-handbook-3rd-edition.pdf

The Department of Health: Webpage: http://www.health.gov.au/internet/main/publishing.nsf/Content/chronic-kidney