Purposes

Neck-shoulder pain (NSP) is a common work-related musculoskeletal disorder (1). The autonomic nervous system (ANS) is a potential element in the pathogenesis of regional muscle pain (2). Altered cardiovascular regulation has been observed in chronic NSP at rest and in response to stressors (3, 4). Importantly, the ANS control of the cardiovascular system is strongly influenced by daily physical activity. Thus, the observed aberrations in ANS regulation in chronic NSP may be due to pain-related changes in daily physical activity. The present study aimed at investigating ANS regulation and physical activity in workers with chronic NSP (N = 29) and symptom-free controls (N = 27) during work and leisure time.

Methods

Ambulatory monitoring of physical activity (seven days) and ANS cardiac activity (72-hours) were performed using accelerometry and electrocardiography, respectively. Time walking, sitting/lying and standing, as well as number of steps were calculated for each hour and averaged for work and leisure time. Heart rate variability indices were calculated in both time and frequency domains, and averaged over work, leisure time and sleep.

Results

The results indicated a reduced level of leisure time physical activity in NSP compared to controls (p<0.05), while no differences were observed for sedentary time. NSP demonstrated diminished HRV during sleep (p<0.05). Positive correlations were found between leisure time physical activity and HRV during sleep (p<0.05).

Conclusions

Reduced leisure time physical activity and diminished nocturnal HRV were seen in persons with chronic muscle pain. Correlations between leisure time physical activity and HRV may indicate that ANS regulation was partly modulated by physical activity in leisure time