This is a cross-sectional study designed to evaluate potential differences in heart rate variability (HRV) indices based on the affected body region (cervical vs lumbar) in individuals with chronic pain. The study will compare HRV parameters between three groups: individuals with chronic neck pain (CNP), individuals with chronic low back pain (CLBP), and a control group without pain. HRV will be assessed using a Firstbeat Bodyguard® device over a 10-minute period, and the data will be analyzed with Kubios® HRV software. The study aims to determine whether autonomic nervous system modulation differs depending on the location of chronic pain.
Study Type
OBSERVATIONAL
Enrollment
93
Universidad de Extremadura
Badajoz, Badajoz, Spain
Root Mean Square of Successive Differences (rMSSD)
This variable represents a time-domain measure of heart rate variability, reflecting parasympathetic nervous system activity and short-term variability in R-R intervals. It is calculated as the root mean square of differences between successive R-R intervals. rMSSD is an established metric to assess vagal modulation and is sensitive to changes in autonomic function.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Standard Deviation 1 (SD1)
A non-linear metric derived from the Poincaré plot of heart rate variability, indicating short-term variability in R-R intervals. It is closely associated with parasympathetic activity and vagal modulation.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Standard Deviation 2 (SD2)
A non-linear metric derived from the Poincaré plot, representing long-term variability in R-R intervals. SD2 is inversely related to sympathetic activity and reflects the balance between sympathetic and parasympathetic modulation.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Stress Score (SS)
This variable is calculated as the reciprocal of SD2, multiplied by 1000. It reflects the level of sympathetic activation, where higher Stress Score values indicate increased stress and reduced parasympathetic activity.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Sympathetic/Parasympathetic Ratio (S/PS Ratio)
This variable represents the ratio of Stress Score to SD1. It reflects the balance between sympathetic and parasympathetic modulation, with higher values indicating sympathetic dominance, commonly observed in chronic pain conditions.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Mean Heart Rate (Mean HR)
Represents the average heart rate (beats per minute) recorded during the data collection period. It serves as a general indicator of autonomic activity, providing insights into the balance between sympathetic and parasympathetic modulation.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Minimum Heart Rate (Min HR)
Represents the lowest heart rate (beats per minute) recorded during the data collection period. This variable reflects periods of parasympathetic predominance and is useful for assessing vagal.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
Maximum Heart Rate (Max HR)
Represents the highest heart rate (beats per minute) recorded during the data collection period. This variable reflects periods of sympathetic activation and provides insights into stress responses during the session.
Time frame: Measured during a single 30-minute session, including a 5-minute baseline and 25-minute data collection period.
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