ESTIMATION OF GROUND REACTION FORCE BY CONSTANT COEFFICIENT METHOD DURING PARACHUTE LANDING

This paper examines the relationship between vertical acceleration measured at the seventh cervical vertebra (C7) and ground reaction force (GRF) during parachute landing. The GRF was estimated using mathematical modelling based on the constant coefficient method and was used to quantify the force exerted on parachutists during landing. A total of 21 Malaysian Army parachutists participated in this study, comprising three professional and eighteen amateur parachutists. Two cameras were employed to capture body movements and obtain kinematic data throughout the landing phase. The results indicate that the estimated maximum peak vertical GRF during the foot-strike phase was 3417 N for professional parachutists and 4604 N for amateur parachutists. Furthermore, professional parachutists were observed to flex their hips and knees before ground contact. From a biomechanical perspective, this movement pattern contributes to a reduction in GRF magnitude. The findings suggest that understanding proper landing techniques through biomechanical analysis may help parachutists improve landing performance before formal instruction, thereby enhancing the efficiency of training for both instructors and trainees.