INTRODUCTION:

Musculoskeletal pain is highly common among the working population. It has been assumed that chronic pain may reduce the activity level in daily life, which in turn may aggravate pain and associated symptoms. However, it is not known whether pain impacts on daily activities among workers. Commonly accepted and validated protocols are needed to gain objective information about possible deviations in physical activity patterns in subjects with chronic musculoskeletal pain.

PURPOSE:

The aim of this cross-sectional study was to investigate the volume and time-pattern of daily physical activity in workers with chronic musculoskeletal pain compared with healthy controls.

METHODS:

Twenty-seven workers with chronic muscle pain primarily in the neck-shoulder region, and 27 age- and gender- matched controls participated in the study. Both groups were recruited from the same global manufacturing company within the industrial sector at a site in Sweden. Physical activity and sedentary behaviour were monitored for seven days, both during work and leisure time, using a single tri-axial accelerometer (PAL Technologies Ltd, Glasgow). Time spent walking, standing and sitting/lying and steps were calculated for each hour. The mean metabolic equivalent (MET) was estimated and used as a measure of energy expenditure. The coefficient of variation (CV) between daytime hours was calculated as a measure of variation.

RESULTS:

For overall daily activity, the mean standing time was significantly higher in the pain group (263 min/day) compared with controls (209 min/day) (p=0.04), whereas no difference was found in energy expenditure or sedentary time. The analyses of time patterns revealed lower energy expenditure in the evening and morning hours among those with pain (mean 1.6 MET/h) compared with the control group (mean 1.8 MET/h) (p<0.05). The pain group showed on average a smaller CV in MET (9%) than the control group (11%) (p=0.02), which indicated a reduced variation in physical activity. There were no significant associations between pain intensity and physical activity.

CONCLUSION:

Despite a normal level of total physical activity, workers with chronic musculoskeletal pain had an altered activity pattern in terms of reduced variation and a lower activity level in leisure time.