Effects of Two Low-Frequency Intradialytic Cycling Training Programs on Functional Capacity in Subjects Undergoing Hemodialysis: A Randomized Controlled Trial

Abstract

Introduction: Functional capacity deteriorates over time in patients on hemodialysis, which is associated with increased mortality risk. This study aimed to assess the effects of two low-frequency (i.e., twice weekly) intradialytic cycling exercise training programs-low- to moderate-intensity continuous training (L-MICT) versus moderate- to high-intensity interval training (M-HIIT) - on functional capacity in patients undergoing hemodialysis.

Methods: Sixty-seven out of sixty-nine patients undergoing hemodialysis of both sexes (44 men and 23 women), aged 35-55 years, completed this study. Patients were randomly assigned to three groups: L-MICT group (n = 23), M-HIIT group (n = 21), and nonexercise control group (n = 23). Patients in the L-MICT group performed intradialytic cycling exercise continuously at a low-to moderate-intensity for 20-30 min. Patients in the M-HIIT group performed 3 × 3-min moderate- to high-intensity cycling exercise, separated by 4-min low-intensity active breaks. The intradialytic cycling programs were scheduled twice a week for 8 weeks. The outcome measure was the functional capacity assessed by the 6-min walk test (6MWT).

Findings: The 6-min walk distance (6MWD) increased significantly in the L-MICT group [p = 0.004, the change score (Δ) = 18.2 meters (m)], in the M-HIIT group (p = 0.001, Δ = 17.6 m), and in the control group (p = 0.014, Δ = 11.4 m) compared to baseline. However, no significant differences were found between groups.

Discussion: Low-frequency intradialytic cycling training programs, either L-MICT or M-HIIT, twice a week for 8 weeks, could similarly induce statistically significant improvements in the 6MWD in people receiving hemodialysis. Nevertheless, the 6MWD changes did not exceed the minimally detectable change previously reported in this population.

Keywords: functional capacity; hemodialysis; high‐intensity interval training; intradialytic cycling; minimally detectable change; moderate‐intensity continuous training; six‐minute walk test.