Fear-avoidance beliefs are associated with exercise adherence: secondary analysis of a randomised controlled trial (RCT) among female healthcare workers with recurrent low back pain

Background Exercise is recommended for the treatment and management of low back pain (LBP) and the prevention of chronicity. Exercise adherence has been only modest in intervention studies among people with musculoskeletal pain. Fear-avoidance beliefs (FABs) are known to affect exercise adherence. The purpose was twofold: to examine which bio-psycho-social factors contributed to exercise adherence during a 6-month neuromuscular exercise intervention among female healthcare workers with recurrent LBP, and to investigate how exercising affects FABs at 6 and 12 months’ follow-up. Methods Some 219 healthcare workers aged 30–55 years with mild-to-moderate re-current non-specific LBP were originally allocated into: 1) exercise, 2) counselling, 3) combined exercise and counselling, and 4) control groups. In the present secondary analysis, groups 1 and 3 (exercise only and exercise+counselling) were merged to be exercisers and groups 2 and 4 were merged to be non-exercisers. Baseline variables of the exercise compliers (≥24 times over 24 weeks; n = 58) were compared to those of the non-compliers (< 1 time/week, 0–23 times; n = 52). The effects of the exercise programme on FABs were analysed by a generalised linear mixed model according to the intention-to-treat principle (exercisers; n = 110 vs non-exercisers; n = 109) at three measurement points (baseline, 6, and 12 months). A per-protocol analysis compared the more exercised to the less exercised and non-exercisers. Results A low education level ( p = 0.026), shift work ( p = 0.023), low aerobic (p = 0.048) and musculoskeletal ( p = 0.043) fitness, and high baseline physical activity-related FABs ( p = 0.019) were related to low exercise adherence. The exercise programme reduced levels of both physical activity- and work-related FABs, and there was a dose response: FABs reduced more in persons who exercised ≥24 times compared to those who exercised 0–23 times. Conclusion Healthcare workers who had lower education and fitness levels, worked shifts, and had high physical activity-related FABs had a lower adherence to the 6-month neuromuscular exercise programme. Exercising with good adherence reduced levels of FABs, which have been shown to be linked with prolonged LBP. Motivational strategies should be targeted at persons with low education and fitness levels and high FABs in order to achieve better exercise adherence.