The Flying Phase in Sprint Runners: Exploring Biomechanical Factors Associated With Performance.

Faggian, S, Lei, LW, Ghezzo, E, Bucciol, M, Airale, M, Del Giudice, M, Breban, SG, Bozzato, M, Costa, I, Cutti, AG, Petrone, N, and Marcolin, G. The flying phase in sprint runners: Exploring biomechanical factors associated with performance. J Strength Cond Res XX(X): 000-000, 2026-Biomechanical parameters of sprint performance are intertwined, yet no single variable has been clearly linked to performance. Moreover, existing training guidelines largely rely on the practical experience of world-leading coaches. This study examined the contribution of biomechanical parameters used by high-level sprint coaches to flying-phase performance and season's best running time (SBRT). Eighteen male sprinters performed all-out 60-m sprints on a track instrumented with a 10-camera motion-capture system and 7 embedded force platforms. Parameters recorded between 30 and 50 m were grouped into 4 categories: temporal (swing and contact time), spatial (step and stride length, hip displacement), kinematic (sagittal absolute angle of thigh, shank, and ankle at maximum knee height; push angle at foot-off; support angle at midstance), and kinetic (horizontal -net, braking, and propulsive- and vertical impulses; peak vertical and horizontal forces). Flying time (FT) and SBRT were the dependent variables of stepwise multiple linear regression models. Stride length and horizontal hip displacement were the strongest determinants of SBRT (adjusted R2: 0.350, p < 0.05) while stride length of the FT (adjusted R2: 0.293, p < 0.05). Support angle solely contributed to SBRT (adjusted R2: 0.303, p < 0.05), whereas braking impulse and peak vertical force contributed as kinetic factors (adjusted R2: 0.609, p < 0.001). Only braking impulse was associated with FT (adjusted R2: 0.228, p < 0.05). Contact time and support angle correlated with peak vertical force (p < 0.05). Overall, kinetic variables outweigh kinematic and spatiotemporal parameters in explaining flying performance. When force platforms are unavailable, coaches may rely on stride length, contact time, and support angle.