The Science

Biometrics in throwing events

Track and field throwing events are four, the discus, the javelin, the shotput and the hammer throw. All these events require well developed technique and high levels of force although the technique is different between events (Zaras et al., 2021). All four events have the same three key biomechanical factors that affect throwing performance and therefore the distance of the throw. These factors are height of release, angle of release and velocity of release (Bartlett and Best, 1988; Hubbard et al., 2001). According to research the velocity of release is the most important biomechanical factor of the three for a successful throwing performance (Badura, 2010; Barnes and Kilding, 2015; Bartlett, 1992; Luca, 2005).

Another factor that affects throwing performance is the anthropometric characteristics of the athletes (Zaras et al., 2021). Track and field throwers are usually quite large with high muscle mass (Hirsch et al., 2016). Resistance training is important for throwing athletes to develop muscle strength, power and force production (Hornsby et al., 2013; Judge, 2007). The body height of throwers is also important as it affect the height of release (Schaa, 2010). Throwers tend to have excess body fat, but it is not clear how or if it affects throwing performance (Zaras et al., 2021).  

Track and field throwers are known for their ability to produce large amounts of force in a short period of time, usually somewhere between 0.15 and 0.24 seconds (Badura, 2010; Bartlett and Best, 1988; Meron and Saint-Phard, 2017). In all throwing events the power from the lower extremities of athletes is transferred to the upper extremities by activating the kinetic chain. The kinetic chain is when force and motion is transferred from one part of the body toanother (Meron and Saint-Phard, 2017). With throwers for example, the force starts in the lower extremities when ground reaction force works on the feet when in contact with theground. Energy is then transferred through the pelvis and trunk, towards the shoulder, arm and fingers holding the object that will be thrown (Sciascia et al., 2012).  

All track and field throwing events require rotation and hyperflexion of the lumbar spine and well-developed technique can prevent injuries. To be able to throw a heavy object a great distance a combination of power, strength, flexibility, timing and coordination is essential. Flexibility training can improve throwing performance as it helps the athletes hold position and generate leverage and torque when throwing. The focus should be on hamstrings, hip flexors, shoulder internal rotators and abdominal rotators using dynamic stretches (Meron and Saint-Phard, 2017).

Although the four track and field throwing events have similar biometrics and biomechanical requirements the technique for them is very different. There are many factors that affect throwing distance for each event, but we will only look into few of them in this paper.

The two most common techniques in shot put are the glide throw and the rotational throw. However, the rotational throw has mostly taken over the glide throw so we will focus on that in this paper (Schofield et al., 2019). The rotational throw is split into five phases; double support phase, first single support phase, flight phase, second single support phase and delivery phase (Byun et al., 2009). Height of release is a significant factor in a successful shot put throw so the anthropometry of athletes is something to consider (Lipovšek, et al., 2011). The taller the athlete the higher the angle of release and the athlete is more likely to achieve good results. Coordination and rotational movements in a rhytmic seqence are important for a successful rotational throw in shot put. The placement of the foot in the beginning of second double support phase has been shown to influence the length of the throw. Torsion angle is another important factor that affects throwing technique especially after the first flight phase (Lipovšek, et al., 2011).

The discuss throw is split into five phases; first double support phase, first single support phase, airborne, second single support phase, second double support phase and delivery phase (Dinu et al., 2019). Several biomechanical factors influence the success of the discus throw, including the angle, speed, height, and direction of release. The optimal angle of release is around 35 degrees, which allows for maximum throwing distance. The speed of release is influenced by the rotational speed of the thrower and the release angle. A higher release height results in a greater throwing distance, while the direction of release should be aligned with the throwing sector (Bartlett, 1992). The biomechanical factors of technique differ between male and female discus throwers. For male discus throwers, the hip-shoulder separation should be low to 0 in the beginning of the throw up until the second single support phase, then the hip-shoulder separation should be as big as possible to generate as much force on the discus as possible. For female discus throwers, the hip-shoulder and shoulder-arm separations during the flight phase, as well as the forward-backward tilts of the trunk at the beginning and end of the throwing procedure, are significant parameters associated with performance of the throw. Additionally, the left foot down moment was found to be the most critical instant, with larger hip-shoulder and shoulder-arm separation angles at this point being associated with better performance (Leigh and Yu, 2007).

The most common technique of the hammer throw is when the athlete swings the hammer, which is connected to a cable and a handle, over their head and then does a number of turns and rotation with it before releasing it (Burke et al., 1989). The length of the cable is around 120 centimetres so the center of mass is something that needs to be considered when analysing the hammer throw. In hammer throwing there are three center of mass that needs to be considered; the thrower‘s center of mass, the hammer‘s center of mass and the hammer-thrower system‘s center of mass (Karalis, 1991). The hammer throw can be split into two phases; double support phase and single support phase (Castaldi et al., 2022). The center three center of mass is different for these two phases. For the Asian record holder the thrower‘s center of mass was at the lowest point in the beginning of the double support phase (Murofushi et al, 2007). Similar results show that for an old world record, the lowest point of the thrower‘s center of mass was instantly after the beginning of the double support phase (Otto, 1990.

Javelin throwing is split into four phases; acceleration phase, release preparatory phase, release phase and braking phase (Menzel, 1986). Research has shown a positive correlation between throwing distance and release velocity in javelin throwing (Tauchi et al., 2009). Biomechanical analysis of javelin throwers using side viewing has shown that higher ranked elite throwers tend to have the right knee joint more flexed than elite throwers ranked lower in the single support phase. This movement is related to higher release velocity for the javelin. The pelvis does rotate but the trunk does not bend forwards at the same time putting the body in a good position to thrust the javelin (Tauchi et al., 2009). Previous research on javelin throwing show that keeping the left knee joint extended in the delivery phase is very important for a successful throw (Morriss and Bartlett, 1996; Murakami et al., 2006).