Introduction
Field hockey is a fast-paced stick and ball sport played in 132 countries worldwide.1 Players must withstand forces generated from fast running and sharp turns while also using their upper body to control and strike the ball.
Although contact injuries from the stick and ball are more common and can have serious consequences, non-contact mechanisms are significant, particularly among female players.2 The lower limb is of particular interest; Barboza et al3 carried out a systematic review of injury data and found that this was the area of the body most commonly injured during hockey, more specifically the knee and ankle with the literature vague on whether the injuries occur through hitting or running. The complex cutting manoeuvres and high-power swing motions required to distribute the ball create a high risk of overuse injury, particularly to the ligaments of the knee and lateral ankle.4 However, limited literature exists on the biomechanics of the sport and how this relates to non-contact injury mechanisms.
Degree of angulation and magnitude of moments around a joint are factors known to correlate with the risk of injury, as they play a key role in the biomechanics of the joint.5–7 Since the lower limb joints allow limited degrees of angulation, particularly in the coronal and transverse planes,8 a foot position that results in angulation of the foot close to its maximum angle, in the respected plane of motion, will increase the risk of injury. Furthermore, there are a number of factors that influence how the magnitude of a force will affect the joint, such as the strength of surrounding muscles. Therefore, there is not a particular magnitude of moment that can be stated as the threshold for injury, making it difficult to quantify the risk of injury. However, through comparison of the four positions against one another, the one that produced the smallest moments the most often, and largest moments the least often, could be said to carry the smallest risk of injury.
There were four foot positions tested in the present study: 0°, 30°, 60° and 90°, relative to the axes of the force plate used to gather motion analysis data. In hockey, a side on stance is common, with the front foot placed at a diagonal to the line of movement of the ball. In this position, the front-foot faces in a similar direction to the rest of the body, with minimal rotation of the ankle joint relative to the body. In the present study, this foot position was defined as 30°. In order to gather motion analysis data with both a smaller and larger degree of angulation at the ankle, a further three foot positions, defined as 0°, 60° and 90° were also tested.
A foot position of 90°was the highest degree included because this results in the foot pointing in the direction of movement. A fourth angle of 60° was included for a more thorough comparison of foot positions between the two extremes of 0° and 90°.
The effect of foot position during a drag flick, a type of stroke performed in hockey when shooting at goal, was investigated by Wild et al.9 The authors proposed that an externally rotated lead foot position during this stroke increases the force at the ankle joint. The hit, which was analysed in the present study, is relevant to a wider range of hockey players than the drag flick, as it is used in all aspects of the game. Therefore, understanding the biomechanics of this stroke is highly relevant.
It appears that adaptation of foot orientation is possible through appropriate training. A recent study involving a neuromuscular training programme for hockey players classed as having unstable ankles resulted in a positive effect on the participants’ ankle positioning.10
This study aimed to propose a lead foot position during the hockey hit that results in the smallest joint angles and moments, from a total of four different foot positions: 0°, 30°, 60° and 90°. The null hypothesis of this study was that no relationship exists between lead foot position and the angles and moments produced during a hockey hit.
