Horizontal Force Influences on Pickup Acceleration

Background/Objectives: Pickup acceleration refers to acceleration initiated from a non-static start, and can be described as a function of approach, transition, and pickup steps. Given the forward-leaning posture adopted during the transition and pickup steps, it was hypothesized that step horizontal force (SFh) production would be a key determinant of pickup acceleration ability. Methods: Forty-eight male athletes performed four 30 m pickup sprints at LED-guided entry velocities of 1.5 m/s-1 (walking) and 3.0 m/s (jogging), with spatiotemporal data collected via a horizontal linear position transducer. Athletes were grouped as “fast” or “slow” based on maximal acceleration (amax) and were compared at time points/steps using independent t-tests. Results: Across both entries, faster athletes achieved significantly higher amax (~13-17%) and maximum velocity (vmax; ~7-8%). At 1.5 m/s, the faster group produced significantly greater SFh during the Transition and Pickup steps (~34-41%), resulting in longer step lengths (SL; ~12%), higher step acceleration (Sa; ~17-32%), and higher step velocities (Sv; ~4-9%). At 3.0 m/s, SFh and Sa remained greater (p ≤ 0.05) in the faster group (~23-41%; 25-32% respectively) but produced fewer significant kinematic differences. It would seem that “faster” pick-up acceleration is associated with greater SFh across the transition and first pick-up steps; this increase in force clearly influences kinematics during a walking entry, but its influence is less apparent during a jogging entry. It is possible that at higher entry velocities, other technical/mechanical determinants become more important, necessitating a more advanced technological approach to studying pickup acceleration than the one used in this study.