Kinematic modifications of the lower limb during the acceleration phase of bend sprinting

Abstract

A decrease in speed when sprinting on the bend compared with the straight has been attributed to kinetic, kinematic and spatiotemporal modifications. Although maximal speed is dependent on an athlete's ability to accelerate, there is limited research investigating the acceleration phase of bend sprinting. This study used a lower limb and trunk marker set with 15 optoelectronic cameras to examine kinematic and spatiotemporal variables of the lower limb during sprinting on the bend and straight.Nine sprinters completed up to six 30 m maximal effort trials in bend (radius 36.5 m, lane one) and straight conditions. An increase in body lateral lean at touchdown resulted in a number of asymmetric kinematic modifications. Whilst the left limb demonstrated a greater peak hip adduction, peak hip internal rotation and peak ankle eversion on the bend compared with the straight, the right limb was characterised by an increase in peak hip abduction. These results demonstrate that kinematic modifications start early in the race and likely accumulate, resulting in greater modifications at maximal speed. It is recommended that strength and conditioning programmes target the hip, ankle and foot in the non-sagittal planes. In addition, sprint training should prioritise specificity by occurring on the bend.

Are the ground reaction forces altered by the curve and with the increasing sprinting velocity?

“…After the starting blocks exit, the left mean stance times in the curve were longer than in the straight (see Figure 5). Consequently, our findings are consistent with what was previously reported at 13 m 28 and 40 m 9,13 . On the other hand, no changes were reported for the right limb (see Figure 5), which is also similar to Churchill et al's 9,13 .…”

Maximum velocity and leg-specific ground reaction force production change with radius during flat curve sprinting

“…The production of cGRF and vGRF may differ between the inside and outside legs as a result of differences in the peak ankle plantarflexor moment ( Judson et al, 2020a ) and peak ankle eversion angle ( Alt et al, 2015 ) during maximum effort curve sprinting, but further research is needed to investigate the effect of curve radii on leg-specific joint kinetics, joint kinematics and GRF production. Athletes seeking to improve curve sprinting performance may benefit from strengthening ankle plantarflexor muscles under a range of frontal plane ankle orientations, as maximum ankle inversion and eversion angles significantly differ during curve versus straight sprinting ( Alt et al, 2015 ; Judson et al, 2020b ).…”

Quantifying demands on the hamstrings during high‐speed running: A systematic review and meta‐analysis

“…High‐speed running was therefore defined as running at or beyond 60% of maximum speed (muscle activation studies) or 4 m per second (m/s) (kinetic studies) and has been used as the minimum criteria for inclusion in this review. Studies where experimental tasks of high‐speed running focused on acceleration, deceleration, curvilinear, and change of direction running data were excluded, due to the associated deviation in mechanics compared with straight line running 23,24 . Overground running studies were limited to flat surfaces, while treadmill‐based studies were included on two conditions; (1) treadmill gradient was set between 0% and 1% and (2) gravity‐altering treadmills were not used to alter subject's normal mass due to their impact on the outcomes measured 25,26 .…”

“…Studies where experimental tasks of high-speed running focused on acceleration, deceleration, curvilinear, and change of direction running data were excluded, due to the associated deviation in mechanics compared with straight line running. 23,24 Overground running studies were limited to flat surfaces, while treadmill-based studies were included on two conditions; (1) treadmill gradient was set between 0% and 1% and (2) gravity-altering treadmills were not used to alter subject's normal mass due to their impact on the outcomes measured. 25,26 If participants' data in a study were recorded only in fatigued states, and/or if exact run speed/relative intensity during data collection was not stated, the study was excluded.…”