Kinematic analysis of rugby union lineout throw
I Griffiths & G Hughes (2005)
Journal of Sports Sciences, 23, 93-223.
The lineout throw in rugby requires the ball to be projected at appropriate height, velocity and angle so that the ball can be caught by a lineout jumper a certain distance away. Sayers (2003, Abst.Nr. PA22– 03, World Congress on Science and Football, Lisbon, Portugal) conducted a detailed study of lineout throwing looking at changes in kinematics as a function of the length of the throw. Sayers’ (2003) results showed an increased lower limb involvement for increased throw distance despite minimal changes in upper body kinematics. Our objective in this study was to re-examine the upper body kinematics in the context of a complete analysis of factors influencing the ball’s trajectory for three different types of throw: short, medium and long. The study was carried out indoors using a Sony Handycam digital camera operating at a frame rate of 50 Hz to obtain two dimensional video data in the subjects’ sagittal plane. Three subjects were used, all experienced at taking lineout throws at international level. The ball was aimed at a 3.425 m tall target set at three different distances from the thrower (5, 10 and 15 m).
Analysis was carried out using Quintic motion analysis software. We obtained data for ball projection velocity and angle of release together with angles and angular velocities measured at the shoulder, elbow, knee, hip and ankle joints. Differences between the types of throw were determined by using one-way analysis of variance using three throws at each distance from each subject.
The parameters for which significant differences were found (at P<0.05) were: projection velocity and peak angular velocities at the elbow, shoulder, knee and ankle joints. (Table 1)
The projection angle was not found to vary significantly between the three throws, neither did the body angles measured at elbow, knee, hip and ankle or the peak angular velocity measured at the hip joint. These results contrast with those of Sayers (2003) where minimal changes in upper body movements were seen. For example, the peak angular velocity measured at the knee joint was 0.72 rad.s-1 for the short throw and 1.64 rad.s-1 for the long throw, while our values are 2.91 rad.s-1 and 5.15 rad.s-1 respectively. Also, Sayers (2003) found the angular velocity at the hip increased significantly from the short throw to the long throw while our study disagreed with this. The reasons for the large differences between our data and those of Sayers (2003) are not known at present. Further investigation might throw further light on the similarities and contrasts between the two sets of data.