Characterisation of running specific prostheses and its effect on sprinting performance

[摘要] ENGLISH ABSTRACT: The development of the running specific prosthetic (RSP) has allowed athletes with lower limb amputations toparticipate at a high level in sports such as sprinting. Literature regarding mechanical properties of RSPs andtheir influence on the athlete's performance, on the other hand, is limited. This makes prosthetic selection adifficult task. The aim of this study was to assess the biomechanical and physiological effects of the mechanicalcharacteristics of different RSPs on an athlete's sprinting performance.The sprint performances of athletes with lower limb amputations were described in a retrospective analysis ofOlympic and Paralympic times between 1992 and 2012, in an attempt to assess whether the technologicaladvances in RSPs is evident. A 14 – 26% performance improvement was found for the T42 and T44 classesof the 100 and 200 m during this time in comparison to 2.2 – 2.8% for the Olympic athlete performances. Theseresults were further supported by the lower competition density found in the amputee groups (Olympic 23.90and 9.29 competitors.s-1; T42 4.53 and 1.93 competitors.s-1). It was therefore proposed that technology playeda significant role in the performance progression of these athletes over the last 20 years.Differences in the characteristics of two RSP models (model E and X) were investigated. This was achievedby athlete independent mechanical testing during which the RSPs were dropped from a height of 30 cm andleft to bounce on a force platform. The results revealed differences in the peak ground reaction force (GRFpeak)(model E > model X; p < 0.05) and maximal RSP compression (ΔL) (model X > model E; p < 0.05). Thisindicated that the RSP model E is more stiffness than the model X.These stiffness characteristics related to discrepancies in sprinting economy of an athlete completing fourmaximal anaerobic running tests (MART) using different RSPs. Two RSP stiffness categories of each model(Ecat4, Ecat6, Xcat4, Xcat6) were used for this testing and was randomly allocated to each testing session. It wasfound that the running speed at which the athlete attained a blood lactate concentration of 10 mmol.l-1 was thehighest with the stiffest RSP (Ecat6), whereas it was the lowest in the softest RSP (Xcat4). Accordingly the lowestfunctional muscular fatigue as measured by a decrease in the pre and post-test counter movement jump heightwas found in this condition (Ecat6 7.35% vs. Xcat4 24.43%).From these investigations it was clear that technology is an important factor in the performances of amputeesprint athletes. Therefore prosthetic selection is of the utmost importance. Differences in the mechanical characteristics of the RSPs influence the sprint physiology and biomechanics and should therefore be takeninto consideration when selecting a RSP.

[发布机构] Stellenbosch University