A new meta-analysis suggests that aerobic exercise could help alleviate the often grueling symptoms of hemodialysis, including depression, fatigue and cramps, advancing researchers' understanding of the relationship between exercise and treatments for kidney failure.
Researchers with the University of Manitoba in Winnipeg reviewed 15 randomized controlled trials involving a total of 508 patients — 283 of whom were assigned exercise interventions — dating back to 1964 to examine the effect of aerobic exercise on symptoms related to hemodialysis, the process of purifying the blood of people whose kidneys aren't functioning properly. Their review, published Thursday in the Clinical Journal of the American Society of Nephrology, found that aerobic exercises could ease common symptoms such as fatigue, depression, restless legs and muscle cramping. The effects on anxiety and disturbed sleep aren't as clear.
Previous studies have explored the potential benefits of exercise for people undergoing hemodialysis. But this analysis is among the first to look at aerobic exercise's effect on the symptoms of the treatment.
"Although exercise has previously shown to be beneficial to physical function and quality of life, there's never really been a rigorous look at what its impact is on symptom burden and the specific symptoms of dialysis," co-author Clara Bohm, a nephrologist and assistant professor with the University of Manitoba, told The Academic Times. "There isn't a lot of work in that area, and considering that the burden of symptoms of dialysis is so high, I think that it's an important opportunity to treat and improve some things that until now have not been easy to treat and improve."
People living with kidney failure often experience myriad symptoms that are "similar to living with metastatic cancer," and hemodialysis can make them worse, the review's authors noted. Most patients report at least one symptom, with others reporting anywhere from six to 20 at a time, including insomnia, anxiety, depression and mood changes.
"It's an incredible burden on our patient population," Bohm said.
Bohm runs an exercise program for people with kidney disease and failure and has anecdotally observed improvements in patients. A body of evidence suggests that exercise can boost the physical function of such patients, but the knowledge isn't widely applied to clinical programming.
"That's the disconnect," she said.
Studies had to involve at least two 20-minute sessions of exercise per week over an eight-week period to be included in the review. But how much exercise is necessary for patients to see benefits is an ongoing debate, Bohm said, as people being treated with dialysis are often physically frail or have co-occurring illnesses such as diabetes or heart disease, and their abilities may be limited.
The researchers did not draw conclusions about the optimal duration and intensity of exercise due to the difficulty of making head-to-head comparisons between studies that examined different exercises. Which exercises are most beneficial is also an open question, as the researchers did not examine the effects of resistance training with weights.
Moreover, the results aren't definitive because some of the studies in the review were based on unvalidated, self-reported questionnaires of patients' symptoms, Bohm said. A broader sample of people undergoing long-term hemodialysis would draw firmer conclusions.
"With a larger sample, you'd get more diverse populations," she said. "There were a lot of exclusions — people who could not enter these studies — so most of the people included were the healthiest of the hemodialysis population. ... We really need to investigate more."
Later this year, Bohm expects to complete a 150-patient study funded by the Kidney Foundation of Canada that will examine the effects of cycling on a wide range of symptoms related to hemodialysis. Her team also recently received funding for an international trial on the long-term effects of exercise during hemodialysis on heart stunning, a damaging side effect of the treatment in which the heart is deprived of blood and oxygen.
Though researchers are just beginning to understand how exercise could benefit people living with symptoms related to hemodialysis, Bohm is comfortable recommending as much movement as possible.
"We should be encouraging hemodialysis patients to be as active as they can, however they can be," Bohm said. "For a long time, we felt like because somebody had kidney failure, a chronic disease, we had to be careful and they couldn't exercise. But many studies have shown it's possible and probably beneficial in many different areas."
The study. "Effect of Aerobic Exercise on Dialysis-Related Symptoms in Individuals Undergoing Maintenance Hemodialysis," published March 25 in the Clinical Journal of the American Society of Nephrology, was authored by Nicholas Hargrove, Nada El Tobgy, Olivia Zhou, Brittany Plant, David Collister, Navdeep Tangri and Clara Bohm, Max Rady College of Medicine, University of Manitoba; Mark Pinder, Reid Whitlock, Navdeep Tangri and Clara Bohm, Seven Oaks Hospital, Winnipeg, Manitoba; Nicole Askin, Laura Bieber, University of Manitoba Libraries; and Navdeep Tangri and Clara Bohm, Department of Community Health Sciences, Max Rady College of Medicine, University of Manitoba.