Mechanical determinants of superior horizontal deceleration performance in multidirectional sportspersons

This study aimed to (a) examine the mechanical determinants of superior horizontal deceleration, and (b) compare ground reaction force (GRF) characteristics of the first and second braking foot contacts during horizontal deceleration between higher and lower deceleration performers. Forty-two trained males from multidirectional team sports performed three maximal deceleration trials following a 15 m sprint, with GRF data over the first two braking steps collected using force plates. Horizontal velocity was collected using a radar gun and p < 0.05 was considered statistically significant. Greater mean and peak deceleration were statistically significantly correlated with greater mean horizontal GRF ratio at both braking foot contacts (ρ = 0.31-0.49, p < 0.05). Comparing lower mean and peak deceleration performers, greater performers displayed statistically significantly greater mean horizontal GRF ratios at both braking steps (ES = 3.53-5.00, p < 0.05), and lower approach momentum (ES = 0.62-0.66). Compared to lower approach momentum performers, greater performers displayed statistically significantly greater mean and peak deceleration scores (ES = 0.62-0.70, p < 0.05). Practitioners should aim to maximize horizontal GRF production and orientate force more horizontally for more effective deceleration. However, faster approach velocities, especially when accompanied with greater body mass (and thus momentum), will likely see a reduction in deceleration performance on account of higher braking demands. This is likely an unavoidable paradox and thus deceleration performance must always be presented considering approach velocity and momentum.