BIOMECHANICAL ASSESSMENT OF LIFTING DYNAMICS, MUSCLE-ACTIVITY AND SPINAL LOADS WHILE USING 3 DIFFERENT STYLES OF LIFTING BELT

Objective. To demonstrate the influence of different types of lifting belts on trunk motion, muscle activity and spine loading during symmet ric and asymmetric lifting exertions. Design. in vivo measurements wer e achieved representing lifting dynamics, applied trunk moments and my oelectric activity. Dynamic spinal loads were determined from a valida ted biomechanical model of lifting. Background. There is a great deal of controversy as to whether lifting belts are a benefit or a liabilit y to manual materia Is-handling activities. A review of the literature demonstrates that there is a large amount of conflicting evidence and few definitive, well-executed studies upon which to base an opinion r egarding these devices. Methods. Fifteen subjects lifted boxes of 14 k g and 23 kg from sagittally symmetric and asymmetric origins to an upr ight posture. Dynamic trunk motions, lifting moments, myoelectric acti vity and modelled spinal loads were examined as a function of three be lt styles (elastic, leather, and orthotic) and compared with results f rom a no-belt condition. Results. Lifting belts reduced peak trunk ang les, velocities and accelerations in the sagittal, lateral and transve rse planes. However, only the elastic belt successfully reduced trunk motions in all three dimensions. The orthotic belt significantly incre ased the lifting moment associated with a given weight. A minor redist ribution in muscle activity was observed when wearing an elastic belt. A statistically significant reduction in spinal load was associated w ith the elastic belt. However, a great deal of variability between sub jects was noted. Some subjects experienced increased spinal load while wearing the elastic lifting belt. Conclusions. These results demonstr ate that the biomechanical operation of lifting can be influenced by t he type of lifting belts used. Relevance Results demonstrate that lift ing belt style is a significant factor in the biomechanical response t o belt usage. Although some belts influence trunk motion and statistic ally reduce spinal load, they should not be universally prescribed for a population. It is clear that some individuals suffer increased spin al load while wearing lifting belts. (C) 1997 Elsevier Science Ltd.