Reliability of the Heart Rate Variability Registered Through Polar Cardio Frequency Meter in Individuals With Chronic Low Back Pain

Objective: The purpose of this study was to analyze the intra- and inter-examiner reliability of the analysis of heart rate variability (HRV) captured by a Polar cardio frequency meter in individuals with chronic nonspecific low back pain. Methods: The study included 35 individuals with nonspecific low back pain, both sexes, aged 18 to 45. We used a Polar V800 cardio frequency meter to capture HRV in individuals in different positions, and we calculated the reliability through the intraclass correlation coefficient (ICC). Results: Regarding intra-examiner reliability, we found excellent reliability of HRV analysis in the supine position (ICC ranging from 0.89 to 1.00) and in the standing position (ICC ranging from 0.95 to 0.99). In addition, for inter-examiner reliability, we found substantial to excellent reliability of the HRV analysis in the supine position (ICC ranging from 0.76 to 0.98) and moderate to excellent reliability in the standing position (ICC ranging from 0.73 to 0.99). Conclusion: The HRV analysis captured by a Polar cardio frequency meter presented adequate reliability when considering different times and different examiners.