Communications to the Fifth International Conference on Sport, Leisure and Ergonomics: Influence of carrying heavy loads on soldiers’ dynamic trunk and head posture

Military personnel are required to carry heavy loads while marching for a substantial component of training and combat. Previous studies in the literature have concentrated on the physiological effect of load carriage, whereas biomechanical research has concentrated on only a few specific load carriage systems. In terms of dynamic posture, research has been conducted on the forward lean of the trunk. This study examined changes in dynamic posture of the trunk and head due to four different military loading conditions: (1) baseline – wearing shorts and T-shirt, standard issue boots and helmet and carrying a rifle (average weight 7.95 kg); (2) webbing – as in the baseline condition with the addition of standard waistbelt webbing weighing 8 kg; (3) backpack – as in the webbing condition with the addition of a standard issue backpack weighing 24 kg; (4) LAW – as in the backpack condition with the addition of a Light Antitank Weapon weighing 10.1 kg (total load 50.05 kg). Twenty male soldiers were evaluated using a two-dimensional CODA motion analysis system. Measurements of trunk and head on neck angle in the sagittal plane were made under the four loaded conditions while walking at a self-selected pace. Temporal parameters of gait were also measured. The addition of load resulted in significant changes (P<0.05) to the position of the head and the trunk during movement. As seen in previous posture research, an increase in load resulted in an increase in forward lean of the individual. This change has been associated with injury, muscle strain and joint problems due to excess load being placed on supporting structures. In addition, an increased forward head position was also noted with the current load carriage conditions. This is an area which has received limited attention in the literature. Understanding how occupational load carriage affects users provides a baseline for improvements in design of equipment and load carriage training.