The Effect of Intradialytic Exercise on Calcium, Phosphorus and Parathyroid Hormone: A Randomized Controlled Trial

Dialysis patients suffer from a number of problems, one of which is reduced ability, decreased functional capacity, and consequently reduced physical capability. Forced inactivity due to immobility in dialysis sessions and the need to rest and relieve fatigue for a few hours after each session cause patients to become more inactive day by day, and according to various studies, inactivity in these patients along with reduced physical capabilities increase the risk of cardiovascular disease (CVD), which is a risk factor for mortality in these patients.

On the other hand, inactivity is an independent predictor of hospitalization and mortality in these patients.

The mortality rate of dialysis patients is much higher than that of healthy people, to the extent that it is reported to be about 10 to 30 times higher. The life expectancy of these patients is between 30 and 50 percent lower than that of people without the same age and sex. Dialysis patients suffer from many CVDs such as high blood pressure, vascular disease, congestive heart failure and arrhythmias. CVDs in patients are related to traditional risk factors such as diabetes, hypertension, sedentary lifestyle and non-traditional risk factors such as anemia, inflammation, abnormal calcium metabolism and phosphorus and oxidative stress. Studies have shown that high levels of calcium, phosphorus , calcium- phosphorus product and parathyroid hormone are associated with fatal and non-fatal cardiovascular events and all-cause mortality in dialysis patients.

One of the most common complications of chronic kidney disease is hypophosphatemia. Phosphate metabolism is regulated by the interaction of the kidneys, bones and intestines. This balance is impaired in kidney patients and the calcification process occurs through disturbances in the regulation of calcium, phosphate, and hyperparathyroidism. Hyperparathyroidism is considered as one of the aggravating causes of anemia as well as resistance to erythropoietin treatment in hemodialysis patients. Due to the effect of parathyroid hormone in the regulation of calcium and the anabolic and catabolic role of the bones, the regulation of this hormone is essential for all people, especially dialysis patients.

Human studies have shown that the regulation of parathyroid hormone and calcium and phosphorus metabolism are dependent on physical activity, and they have introduced exercise as an effective way to regulate this hormone. Considering the various effects of exercise on dialysis patients, a study has been designed to investigate the effect of concurrent exercise during dialysis on changes in calcium levels, phosphorus, calcium-phosphorus product, and parathyroid hormone.