Factors explaining improvement of isoinertial lifting-capacity

A clearer understanding of the factors involved in improving lifting-capacity may assist professional health workers to enhance patient's functioning and minimize chronic back pain. However, few studies have examined this association. This study is part of a trial comparing two secondary back pain prevention programs. It aims to identify anthropometric, physical, psychic and demographic baseline variables (baseline model), and over time change variables (comprehensive model), which explain the alteration of lumbar isoinertial lifting-capacity, from baseline to post-treatment.

The association between these variables' baseline- or change values, and the change of lifting-capacity (PILE-test) over time, were analyzed with multiple regression analyses. Potential variables for the regression analyses were identified within a standardized stepwise selection process.

In the baseline model, 35.2% of the variance in lifting-capacity was mainly explained by a low baseline score of lumbar lifting-capacity, high body weight and gender. In the comprehensive model, 41.9% could be mainly explained by the same baseline variables, an increase of perceived exertion during the PILE-tests and decrease of fear-avoidance caused by work.

The results suggest that treatments to improve lifting-capacity in individuals with mild low back pain should particularly address the reduction of fear-avoidance beliefs. Although strong conclusions cannot be drawn from this study due to methodological limitations, they may be helpful to assign patients to appropriate and most beneficial treatment programs, as well as to develop specific programs. Fear-reduction may be an important target for early interventions in regard to functional capacity.