The Influence of Different Starting Block Distances on Internal Tibial Load in Elite Sprinters.

In sprint running, the starting block distance (SBD) directly influences an athlete's start performance, yet there is a lack of research exploring how block distance affects internal tibial load. Therefore, this study examined internal tibial loading in 28 elite sprinters using finite element analysis. Maximum principal stress, shear stress, total deformation, and bending moments were assessed under 3 front block distances (50%, 60%, and 70% of leg length). A 2-way analysis of variance evaluated the effects of gender, SBD, and their interaction. The results showed a significant main effect of gender on maximum principal stress (P < .001), tibial bending moment (P < .001), maximum shear stress (P < .001), and total deformation (P < .001). Furthermore, significant gender-by-SBD interactions for maximum principal stress (P = .001, ηp2=.16) and maximum shear stress (P = .02, ηp2=.05) indicated distinct mechanical responses between male and female athletes in response to SBD settings. This finding suggests that adopting block settings previously reported to optimize start performance (eg, front block distance [FB]/interblock spacing length [SL] 50/45) may inevitably increase internal tibial loading, potentially elevating the risk of cumulative injuries such as medial tibial stress syndrome.