Influence of the mode of load carriage on the static posture of the pelvic girdle and the thoracic and lumbar spine in vivo.

The influence of various modes of carrying a load of 16 kg (15.69 DaN) on the static positioning of the pelvic girdle and the thoracic and lumbar segments of the spine was examined in seven male subjects. The displacement of cutaneous markers attached to easily palpable skeletal landmarks was recorded using 4 CCD cameras; the data acquired were analysed using an optoelectronic technique (SAGA3). The subjects stood upright on an AMTI biomechanical force platform, from which the ground reaction forces enabled displacements of the centre of gravity axis and thus the moment of the mass carried to be determined. The modes of load carriage examined were: 1) in a case in the left hand; 2) in a case in the right hand; 3) equally in two cases; 4) on the head; 5) in a rucksack; and 6) in an anterior bag. The results showed displacements of the pelvic girdle, the caudal and cranial lumbar segments, and the caudal and cranial thoracic segments in the three orthogonal planes (sagittal, frontal and transverse). The influence of the moment created by the load was seen in the statokinesigrams. The use of external markers using an optoelectronic technique, in association with the ground reaction forces, enables the mode of load carriage to be determined. The results show that the influence of the moment exerted by the mode of load carriage on the gravity axis has important ergonomic consequences.