Fear of movement is not associated with trunk movement variability during gait in patients with low back pain.

BACKGROUND

Literature describing differences in motor control between low back pain (LBP) patients and healthy controls is very inconsistent, which may be an indication for the existence of subgroups. Pain-related psychological factors might play a role causing these differences.

PURPOSE

To examine the relation between fear of movement and variability of kinematics and muscle activation during gait in LBP patients.

STUDY DESIGN

Cross-sectional experimental design.

PATIENT SAMPLE

Thirty-one Chinese LBP patients.

OUTCOME MEASURES

Self-report measures: Visual Analog Score for pain; TAMPA-score; Physiologic measures: electromyography, range of motion.

FUNCTIONAL MEASURES

LBP history; the physical load of profession, physical activity.

METHODS

Patients were divided in high and low fear of movement groups. Participants walked on a treadmill at four speeds: very slow, slow, preferred and fast. Kinematics of the thorax and the pelvis were recorded, together with the electromyography of five bilateral trunk muscle pairs. Kinematic and electromyography data were analysed in terms of stride-to-stride pattern variability. Factor analysis was applied to assess interdependence of 11 variability measures. To test for differences between groups, a mixed-design multivariate analysis of variance was conducted.

RESULTS

Kinematic variability and variability of muscle activation consistently loaded on different factors and thus represented different underlying variables. No significant Group effects on variability of kinematics and muscle activation were found (Hotelling's Trace F=0.237; 0.396, p=.959; .846, respectively). Speed significantly decreased kinematic variability and increased variability in muscle activation (Hotelling's Trace F=8.363; 4.595, p<.0001; <.0001, respectively). No significant interactions between Group and Speed were found (Hotelling's Trace F=0.204; 0.100, p=.762; .963, respectively).

CONCLUSIONS

The results of this study do not support the hypothesis that variability in trunk kinematics and trunk muscle activation during gait in LBP patients are associated with fear of movement.