Effect of Two Intradialytic Exercise Programs on Heart Rate Variability in Hemodialysis Patients
Description
Objective: To determine the effects of a non-immersive virtual reality (NIVR) program versus a conventional intradialytic exercise (CIE) program on heart rate variability (HRV) in individuals with chronic kidney disease (CKD) undergoing hemodialysis (HD). Materials and Methods: A quasi-experimental study was conducted with 24 ambulatory patients from the HD unit of the Consorci Sanitari de Terrassa, Barcelona, Spain, between August and December 2024. Patients were assigned by convenience to the NIVR or CIE groups. A pre–post assessment was performed for variables related to the time, frequency, and nonlinear domains of HRV using the Polar H10 sensor. Results: The CIE group demonstrated clinically significant improvements in variables such as the stress index (SI; d = 0.80) and SD2 (d = 0.63), reaching marginal statistical significance for both outcomes (P = 0.07 and P = 0.08, respectively). In contrast, the NIVR group showed small-to-moderate clinical significance in LF (d = 0.77), HF (d = 0.77), and SD2 (d = 0.43), with P > 0.05. A 40% reduction in cardiovascular risk was observed in participants initially classified as high risk in the CIE group (P = 0.02). NIVR was not superior to CIE in improving cardiac autonomic modulation. Conclusion: CIE yielded more favorable outcomes in cardiac autonomic modulation compared with NIVR. However, given the study limitations, it is not possible to conclusively determine which program provides greater benefits. This research serves as a foundation for future studies designed to address the identified limitations and enable more robust comparisons.
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Measurements were performed prior to the exercise intervention and at the completion of the 12-week program. Before the assessments, participants were instructed to avoid alcohol consumption, caffeine intake, and strenuous physical exercise during the 24 hours preceding the evaluation. Data collection was conducted during the first half of one of the scheduled weekly dialysis sessions. Each participant was positioned in the supine position for 10 minutes, during which spontaneous breathing was encouraged. Prior to the assessment, the purpose of the test and the procedure were explained to the participants in order to reduce procedure-related anxiety. A Polar® H10 heart rate sensor was used and placed around the thorax at the lower third of the sternum, ensuring that the chest strap maintained firm and continuous contact with the skin without causing discomfort. The recording duration was established based on previous studies demonstrating the clinical reliability of short-term HRV measurements under controlled conditions.²³ The sensor was paired via Bluetooth with a smartphone running the Elite HRV application (Elite HRV Inc., North Carolina, United States). Upon completion of the recording, the data were exported via email as a .txt file. Subsequently, the file was processed using Kubios HRV software, Standard version 3.4.1, released in 2020. Additionally, the “Very low” beat correction algorithm was applied to ensure the removal of potential artifacts, in accordance with previously published recommendations.²⁴ The software generated linear indices, including time-domain variables: R–R interval (RR), heart rate (HR), standard deviation of normal R–R intervals (SDNN), root mean square of successive differences between adjacent R–R intervals (RMSSD), percentage of successive NN interval pairs differing by more than 50 milliseconds (pNN50), and stress index (SI). Frequency-domain variables included low frequency (LF), high frequency (HF), and the low-frequency to high-frequency ratio (LF/HF). Nonlinear components were also analyzed, including the standard deviation of R–R intervals perpendicular to the line of identity in the Poincaré plot (SD1) and the standard deviation along the longitudinal axis (SD2). In addition, cardiovascular risk was assessed based on SDNN values, using the following reference thresholds: high risk <50 ms, moderate risk 50–100 ms, and low risk >100 ms, previously reported in the literature as the gold standard for 24-hour recordings.⁹˒²⁵
Institutions
- Universidad Nacional de ColombiaBogota