Kicking in football is an essential, common, and distinctive part of a players activity. During an average 90-minute game, a player has 51 contacts with the ball, 26 with the foot. An analysis of injury risk while playing football indicated that kicking accounted for 51% of potential actions that could lead to injury. Approximately 60%-80% of severe injuries to football players occur in the lower extremities, most commonly at the knee (29%) and ankle (19%). Kicking is the most reproducible action in football which can be studied in lab environments. We aimed to analyse the biomechanical factors that contribute to better kick performance and identify injury risk in Indian league level football players.
Materials And Methods
25 professional Male Football players participated in this descriptive cross-sectional study. Five successful instep kicks were performed against a goalpost placed 11m from the football. 35 retroreflective markers were affixed over the player’s skin on anatomical landmarks. The instep kick was captured using sixteen 3D VICON motion capture cameras (250 fps), two 2D Bonita cameras (125 and 250 fps), AMTI force plates and ball velocity using Radar speed gun (Ball coach). The data was analysed using VICON Nexus software version 2.7 and key biomechanical parameters were quantified and compared with the existing literature. Descriptive statistics were done using R software version 4.0.1.
Players had a mean age of 18.8 ± 0.96 years with professional training of 6.72 ± 3.17 years. The study group consisted of 36% Midfielders, 16% goalkeepers, 36% defenders and 12% strikers. The mean hip shoulder separation angle measured 20.33 ± 6.15° which was found to be significantly lower (p<0.05). The peak trunk rotation velocity and peak hip flexion velocity of 437.95 ± 118.37°/s and 565.86 ± 129.81°/s respectively was noted to be similar to the values in literature with positive correlation to ball velocity. Supporting leg knee flexion at ball contact was 43.75 ± 9.18°. The ankle plantarflexion at ball impact measured 33.97 ± 11.05°, found to be significantly higher than the normative but positively correlated to ball velocity. Mean Peak vertical ground reaction force was found to be higher than the reference values (3.44 ± 0.61N/Kg BW). The mean duration of the kick cycle was significantly lower especially the followthrough phase amounting to 0.062 ± 0.01s.
Peak Hip Flexion velocity, Trunk Rotation Velocity and Ankle Plantarflexion correlate with better kick performance. Greater ankle range of motion at ball impact predisposes to a higher incidence of Anterior Ankle Impingement syndrome. Higher Ground Reaction Forces and Shorter Follow-Through Phase imply that the players are prone to deceleration injuries of the lower back, knee and ankle. These findings will aid in the strategic planning of injury prevention programs and refine kicking technique thus optimising performance.