What Is the Optimal Timing for Intradialytic Resistance Exercise? A Randomized Controlled Trial

Purpose and Objective: The aim of our study is to examine the effect of intradialytic (IR) resistance exercise time on blood pressure, physical performance and quality of life in hemodialysis (HD) patients. With this study we are planning to do, we aim to help HD patients regulate their blood pressure values and increase their muscle strength so that they can be more independent in their daily living activities and thus improve their quality of life.

Original Value: HD is the reorganization of the fluid and solute content of the blood taken from the patient by means of a membrane and with the help of a machine. The treatment requirements of HD patients (the HD session is usually applied two or three days a week and each application takes about 4 hours, as well as the plasma withdrawal from the body during HD) and long-term immobilization usually cause low blood pressure. This may cause some patients to have an intradialytic hypotensive attack (IDHA) due to the excessive decrease in blood pressure during HD. IDHA, on the other hand, is associated with severe abdominal pain, nausea, vomiting, dizziness, blackout, muscle cramps, with a decrease in systolic blood pressure of more than 20 mmHg compared to the predialysis (pre-dialysis) value or a decrease in mean systolic pressure of more than 10 mmHg from the predialysis value. It is defined as the coexistence of symptoms such as cramps and severe anxiety.

It is a known fact that regular exercises have a blood pressure lowering effect in the chronic period, and it is observed that exercises performed regardless of type (aerobic, resistant or combined) increase blood pressure in the acute period. Because blood flow is restricted due to the increase in pressure in the muscle during exercise, metabaroreceptors and mechanoreceptors in the active muscle stimulate the cardiovascular center in the medulla, and both systolic and diastolic pressure increase in order to exclude intramuscular pressure and provide perfusion. This is a response of the body to exercise and occurs as a result of normal physiological mechanisms.

Due to theoretical concerns that the exercise applied in the last two hours of the HD session may exacerbate hemodynamic instability, it is generally recommended to exercise in the first two hours of HD. However, there is also evidence showing that exercise can be done in the last two hours of the HD session. The increase in these evidences, especially in recent years, reveals that there is a need for studies on the effectiveness and reliability of IR exercise application time. The tendency of the blood pressure to drop more in the last half of the HD session (due to the increase in the amount of plasma withdrawn from the patients as time progresses) suggests that an exercise program that can be given in these minutes may provide a significant benefit to the patients, considering the acute blood pressure-raising effect.

From another point of view, studies show that resistance exercises (because it increases intramuscular pressure more) increase blood pressure more in the acute period than aerobic exercises. There are limited studies comparing the effects of aerobic and resistance exercises on blood pressure in HD patients. Limited existing studies have also revealed that resistance exercise raises blood pressure more than aerobic exercise in the acute period in HD patients. Therefore, it is thought that it would be more beneficial to include resistant exercises in the exercise program to be given to the patients in the last two hours.