Characterisation of the responsive properties of two running-specific prosthetic models

Background: The need for information regarding running-specific prosthetic properties has previously been voiced. Such information is necessary to assist in athletes’ prostheses selection. Objectives: This study aimed to describe the characteristics of two commercially available running-specific prostheses. Study design: The running-specific prostheses were tested (in an experimental setup) without the external interference of athlete performance variations. Methods: Four stiffness categories of each running-specific prosthetic model (Xtend™ and Xtreme™) were tested at seven alignment setups and three drop masses (28, 38 and 48 kg). Results for peak ground reaction force (GRFpeak), contact time (tc), flight time (tf), reactive strength index (RSI) and maximal compression (ΔL) were determined during controlled dropping of running-specific prostheses onto a force platform with different masses attached to the experimental setup. Results: No statistically significant differences were found between the different setups of the running-specific prostheses. Statistically significant differences were found between the two models for all outcome variables (GRFpeak, Xtend > Xtreme; tc, Xtreme > Xtend; tf, Xtreme > Xtend; RSI, Xtend > Xtreme; ΔL, Xtreme > Xtend; p < 0.05). Conclusion: These findings suggest that the Xtreme stores more elastic energy than the Xtend, leading to a greater performance response. The specific responsive features of blades could guide sprint athletes in their choice of running-specific prostheses. Clinical relevance Insights into the running-specific prosthesis (RSP) properties and an understanding of its responsive characteristics have implications for athletes’ prosthetic choice. Physiologically and metabolically, a short sprint event (i.e. 100 m) places different demands on the athlete than a long sprint event (i.e. 400 m), and the RSP should match these performance demands.