Long jumpers with a below the knee amputation (BKA) who use their prosthesis for the take- off step are able to achieve remarkable performances. Yet, the underlying biomechanics are not comprehensively understood. However, knowledge of this is important for adapting training protocols, for distinguishing injury mechanisms, and for informing the devolvement of prosthetic design. Furthermore, the findings of this project might be a relevant source of information for future adaptation of olympic and paralympic regulations.
Within the framework of a multinational research project, from which the present dissertation results, motion analyses were conducted on three long jumpers with BKA and seven non- amputee athletes. Kinematics and kinetics during sprinting and the long jump take-off step together with athlete-specific anthropometrics served as input data for an inverse dynamic multi-segment model used for detailed three-dimensional analyses.
Athletes with BKA demonstrated different characteristics in terms of centre of mass (COM) and joint mechanics during sprinting and the long jump take-off compared to non-amputee athletes. Athletes with BKA had a slower run-up velocity but had a more efficient take-off step. During the take-off step, athletes with BKA positioned their prosthesis differently in relation to their COM compared to the foot positioning of the non-amputee athletes, and the COM motion characteristics were different between the two groups. In general, athletes with BKA had lower muscular-skeletal loading at the hip and knee joints during the take-off step, which results from shorter lever arms between the ground reaction force vector and the joint centres in athletes with BKA compared to the non-amputee athletes. The take-off characteristics of athletes with BKA were similar to the jump off a springboard, whereas the take-off step characteristics of non-amputee athletes resembled the known mechanism of “pivoting” to generate vertical take-off velocity.
As a result of mechanical constraints or limited muscular-skeletal capacities, long jumpers with or without BKA, respectively, illustrate motion characteristics, particularly during the take-off step of the long jump, which on the one hand are based on different locomotion mechanisms and on the other hand cannot be adopted by the other group.