The effect of approach velocity on pelvis and kick leg angular momentum conversion strategies during football instep kicking

Multiplanar lumbar, pelvis and kick leg sequencing during soccer instep kicking from different approach angles

Multiplanar kinematic and kinetic sequencing from different approach angles can highlight how soccer players perform fast and accurate kicks. This study therefore aimed to a) determine multiplanar torso, pelvis and kick leg sequencing during instep kicks and b) highlight the effect of different approach angles on these sequencing patterns. Twenty male soccer players (mass 77.9 ± 6.5 kg, height 1.71 ± 0.09 m, age 23.2 ± 3.7 years) performed kicks from self-selected (∼30-45°), straight (0°) and wide (67.5°) approaches and multiplanar lumbo-pelvic, hip and knee angular velocities, moments and powers were derived from 3D motion analysis. The results suggest tension arc release between the upper and lower body functions as a two-stage mechanism. The first phase of arc release was characterised by increases in concentric hip flexion and transverse lumbo-pelvic velocities towards the ball. The second phase was characterised by increasing concentric lumbo-pelvic flexion and knee extension work to angularly accelerate the kicking knee towards foot-to-ball contact. Further, alterations in kinematic and kinetic sequencing helped maintain performance (ball and foot velocities at ball contact) and accuracy at approach angles other than self-selected. These findings can help coaches and practitioners design effective training practices.

Modelling the relationships between EEG signals, movement kinematics and outcome in soccer kicking

The contribution of cortical activity (e.g. EEG recordings) in various brain regions to motor control during goal-directed manipulative tasks using lower limbs remains unexplored. Therefore, the aim of the current study was to determine the magnitude of associations between EEG-derived brain activity and soccer kicking parameters. Twenty-four under-17 players performed an instep kicking task (18 m from the goal) aiming to hit 1 × 1 m targets allocated in the goalpost upper corners in the presence of a goalkeeper. Using a portable 64-channel EEG system, brain oscillations in delta, theta, alpha, beta and gamma frequency bands were determined at the frontal, motor, parietal and occipital regions separately for three phases of the kicks: preparatory, approach and immediately prior to ball contact. Movement kinematic measures included segmental linear and relative velocities, angular joint displacement and velocities. Mean radial error and ball velocity were assumed as outcome indicators. A significant influence of frontal theta power immediately prior to ball contact was observed in the variance of ball velocity (R 2 = 35%, P = 0.01) while the expression of occipital alpha component recorded during the preparatory phase contributed to the mean radial error (R 2 = 20%, P = 0.049). Ankle eversion angle at impact moment likely mediated the association between frontal theta power and subsequent ball velocity (β = 0.151, P = 0.06). The present analysis showed that the brain signalling at cortical level may be determinant in movement control, ball velocity and accuracy when performing kick attempts from the edge of penalty area. Trial registration number #RBR-8prx2m-Brazilian Registry of Clinical Trials ReBec.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-022-09786-2.

Defining movement strategies in soccer instep kicking using the relationship between pelvis and kick leg rotations

Growing evidence suggests skilled ball kickers use distinct pelvis and kick leg strategies to achieve successful performance. However, since the interaction between different strategies remains unexplored, the aims of this study were to a) examine relationships between pelvis and kick leg rotations in male players performing soccer instep kicks and b) classify different 'types' of kickers based on the observed movement strategies. Twenty semi-professional players performed kicks for maximal speed and accuracy, and kick leg and pelvis kinematics were analysed using 3D motion capture (1000 Hz). A strong relationship was found between change in pelvis transverse angular velocity and thigh-knee angular velocity ratio upon ball contact (r = 0.76, p < 0.001), and participants were categorised by their location on kick leg (thigh-knee) and pelvis (maintainer-reverser) continuums. Knowledge of a player's preferred strategy can inform departure from 'one size fits all' technical and conditioning training practices towards more individualised approaches. For example, pelvis maintainer-thigh dominant kickers might benefit from focus towards the concentric capabilities of the hip flexors, whereas reverser-knee dominant kickers might benefit from developing the ability to decelerate the pelvis and thigh to induce motion-dependent angular acceleration of the lower leg towards the ball.