The effect of loads carried on the shoulders

This work describes a way of measuring the forces acting on the shoulders w hen subjects carry a backpack. A frame pack was carried by 12 male subjects : 4 hikers, 4 occasional hikers, and 4 novices. They walked for 30 minutes on a 5% inclined treadmill at 3.6 km/h to simulate moderate hiking. The loa d was carried at T9 and was increased (10, 15, and 20 kg) after 1, 20, and 25 minutes. The data from force transducers placed on the shoulder straps w ere collected for 30 seconds at 100 Hz. Shoulder strain appeared to be the limiting factor in load carriage. The optimal carrying method depends on th e person, but it has been shown that decreasing stride length and wearing a ppropriate footwear reduces the strain on the shoulders.