Strain recordings: Explanations about the effects of an anterior trunk support on the strain of a forward trunk bending posture

Effectiveness of a belt supporting the trunk in flexion, positively assessed by a survey at work, was tested in 3 belt configurations (2 belts and no belt) and 3 tests (static and dynamic trunk flexion, work simulation).
Subjective and objective results show that:
- Subjective reduction of the postural strain by the belts is small (p<0.05).
- In the flexion tests muscle activity is not significantly reduced. However, in the work simulation task, strains of the back muscles are reduced by the belts which optimize muscle co-activities and let them more range to adapt. Belt stiffens the body which also leads to a greater mobility of the center of gravity of the subjects.
In conclusion, the results show a significant but small effect of the belts which are not in conflict with the perceived effectiveness of long-term (8 h) use in actual work.