The Second Spine is a vest intended to prevent musculoskeletal injuries caused by heavy backpack loads, while also maintaining the range of motion of the wearer. The vest is formed by multiple segments between the shoulder and a pelvic belt. In normal “off” configuration, the segments are disconnected from each other and the vest is flexible providing full range of motion to the upper body. With the pull of a string in the “on” configuration, the vest becomes semi-rigid creating a secondary pathway to transfer loads between the shoulder and a pelvic belt.
The device was evaluated by a subject who walked on a treadmill while carrying a backpack load of 25% of his body weight (BW). Experiment results showed that the semi-rigid vest reduces the force exerted on the shoulders and induces a more erect posture. Muscle activations in the lower limbs indicate that loads were successfully transferred from the shoulders to the waist while bypassing the vertebral column. These results show that the device can be used to mitigate potential risks of musculoskeletal injuries caused from backpack loads.