The ability to score from placekicks is a trait discriminating winning and losing in elite Rugby Union1. Placekicks account for 45% of points in international Rugby Union, with match outcomes reliant on placekicking success2. Clearly, improving placekicking success can alter match outcomes and should be a key focus in rugby skills coaching. Currently, coaching placekicking techniques mainly relies upon practical experience or findings from other sports or non-elite Rugby Union players tested in laboratory environments. These studies provide limited real-world guidance for placekickers and coaches. Our aim was to determine biomechanical variables that discriminate good and bad placekicking attempts in an ecologically valid environment.
Three competitive male placekickers performed 10 kicks outdoors, 35-meters from the goalposts. Placekicker and ball 3D biomechanics were collected at 300-Hz using a Qualysis 3D motion capture system. Coach and player perceptions and placekick outcomes were recorded to define the three best and three worst kicks for each placekicker. Differences between the best and worst kicks were examined using standardised effect sizes (ES).
Seven variables meaningfully and consistently differentiated the best from worst placekicks in all three players (‘core variables’, Figure 1). In the best kicks, resultant and forward speed of centre of mass were slower at ball contact, but maintained better through contact; the kicking leg reached greater knee flexion during swing and was more flexed at the hip and knee at ball contact; and the trunk was less rotated outwards relative to the kicking direction. Twenty-seven variables were consistently associated with better kicking performance in all players, with a large ES in at least one player (‘meaningful variables’, Figure 1). These variables indicated that the best kicks demonstrated less sideways ball spin, speed, and direction; greater change in vertical and sideways foot speed during ball contact; a more “C” than “J” shape footpath; larger shoulder-to-hip separation; and less ankle motion during swing.
Figure 1. Biomechanical variables associated with successful placekicking.
This exploratory study identified biomechanical variables that discriminated the best from the worst placekicks in competitive rugby players. The identified differences can guide coaching of placekicking at a group level in absence of individual data. The variables and coaching cues that appear important in promoting successful placekicking outcomes include controlling centre of mass approach and follow-through speed, enhancing knee flexion and axial rotation range, being on-top of the ball at ball contact, swooping across the ball with the foot, and minimizing ball sideways movements.
We thank the participants and members from the University of Waikato Adams Centre for High Performance for their assistance.
1.Lim et al., Int J Perform Anal Sport. 2009;9(3):354-367.
2.Quarrie and Hopkins, J Sci Med Sport. 2015;18(2):195-198.