Lower Extremity Assistance for Parachutist (LEAP) Program. Quantification of the Biomechanics of the Parachute Landing Fall and Implications for a Device to Prevent Injuries.

Abstract : This report presents results from two experiments conducted for the lower extremity assistance for parachutist (LEAP) program. These experiments are part of a systematic effort to develop a device to prevent lower extremity injuries to airborne soldiers. To develop such a device, data were collected about the biomechanics of the parachute landing fall (PLF). The data collected included ground reaction forces, ground reaction moments, and displacements of the soldier's lower extremities as he performed a PLF. The experiments were conducted in an indoor laboratory. Test participants jumped from platforms onto a force plate. Their motions were recorded by video cameras as they performed PLFs. In the fist experiment, biomechanical data about PLFs in five legwear conditions were collected: boots, ankle braces, knee braces, ankle and knee braces together, and viscoelastic material covering the force plate. Based on the significant impact reduction of the viscoelastic material, prototype impact-absorbing soles were developed and then tested in the second experiment. The impact-absorbing soles provided significant reductions in impact forces and moments compared to jumps in boots only. Development of a protective device should begin with impact-absorbing soles. Then, braces that protect the joints and allow natural motions should be developed and integrated into a complete lower extremity protective device.