Is an imbalance between physical capacity and exposure to work-related physical factors associated with low-back, neck or shoulder pain?

Objectives This study investigates whether an imbalance between physical capacity and exposure to work-related physical factors is associated with low-back, neck, or shoulder pain. Methods Data of the longitudinal study on musculoskeletal disorders, absenteeism, stress, and health (SMASH), with a follow-up of 3 years (N=1789), were used. At baseline, physical capacity (isokinetic lifting strength, static muscle endurance, and mobility of the spine) and exposure to work-related physical factors were assessed. During the follow-up, low-back, neck, and shoulder pain were self-reported annually. Imbalance was defined as lower than median capacity combined with higher than median exposure, high balance was high capacity and high exposure, and low balance was low capacity and low exposure. Results For both the low-back and neck, imbalance between static endurance and working with flexed postures was a risk factor for pain [relative risk (RR) 1.35, 95% confidence interval (95% CI) 1.08-1.68, and RR 1.36, 95% CI 0.96-1.9 1, respectively]. Low balance was also associated with low-back pain (RR 1.29, 95% CI 1.041.68). Furthermore, low balance between isokinetic lifting strength and lifting exposure was a risk factor for low-back and neck pain [RR between 1.22 (95% CI 0.99-1.49) and 1.35 (95% CI 1.03-1.79)]. No associations were found with shoulder pain. Conclusions Some relationship between low-back and neck pain and combined measures of physical capacity with exposure to work-related physical factors seems to exist, but an imbalance between physical capacity and exposure was not found to yield higher risks than high balance or low balance.