People with chronic kidney disease that has progressed to the point of kidney failure — meaning that their kidneys can no longer effectively filter waste products from their blood — often face significant physical limitations. They may have reduced energy levels due to the buildup of waste products in their blood, and they may have a disability unrelated to kidney function — such as reduced vision or painful peripheral neuropathy — due to diabetes, which is a leading cause of chronic kidney disease. This means that people on dialysis are often not viewed as likely candidates for exercise, and doctors may not even recommend physical activity to these patients. For the latest study, researchers were interested in whether physical activity was linked to better cardiovascular outcomes among people on dialysis — not a given, since certain lifestyle factors may have a greater benefit earlier in the course of a disease process.
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The study’s participants were 6,147 people on dialysis who took part in a study called Dietary Intake, Death and Hospitalization in Adults with ESKD Treated with Hemodialysis (DIET-HD). This study was conducted in 11 countries in Europe and South America. Based on a physical activity questionnaire, participants were classified as physically inactive, occasionally active (irregularly or up to once a week), or frequently active (twice a week or more). Responses showed that 2,940 participants (48%) were physically inactive, 1,981 (32%) were occasionally active, and 1,226 (20%) were frequently active.
More physical activity linked to lower death risk
Participants were followed for a median follow-up period of 3.8 years, for a total of 19,677 person-years. During this time, 2,337 participants (38%) died, and 1,050 of these deaths (45%) were attributed to cardiovascular disease. After adjusting for factors other than physical activity that are known to affect the risk of death from cardiovascular causes — such as age and known cardiovascular risk factors — the researchers found that physical activity was significantly linked to the risk of dying. Participants who engaged in occasional physical activity were 20% less likely to die from all causes, and 18% less likely to die from cardiovascular causes than those who were physically inactive. Those who engaged in frequent physical activity were 18% less likely to die from all causes, and 23% less likely to die from cardiovascular causes than who were physically inactive. When it came to death from cardiovascular causes, these numbers support a dose-dependent response from physical activity — meaning that the more active you are, the lower your risk.
The researchers wrote that there could also be a dose-dependent response from physical activity on death from all causes that the study didn’t capture, “due to the [inability] of the single-question assessment to discriminate across levels of intensity of physical activity.” They explained that, potentially, “the single self-reported question was effective at differentiating between sedentary and active individuals but not as effective at differentiating low levels of physical activity from higher levels.” In any case, they noted, death due to non-cardiovascular causes was relatively rare among frequently active participants.
It’s also notable that the study found a significant benefit from physical activity even among people who didn’t meet typical exercise recommendations, compared with getting no physical activity at all. “Such findings are encouraging for people undergoing hemodialysis who often face physical limitations and reduced exercise capacity,” the researchers wrote, and support the idea that no matter how many limitations you face, it’s important to be as active as you can be.