The Question: How can an athlete maximize the distance of a javelin throw? Technique (Qualitative) Without a good understanding of the processes and technique of a movement, athletes and coaches cannot apply qualitative biomechanical principles to improve results. The javelin throw is a complex performance with several variables (small and large) that affect the range of throwing distance. Conversely, the same result can be achieved using a mixture of techniques (Valleala, 2012, p.4 & Valleala, 2009, p.1). Grip – The javelin should lie in the hand according to the direction of the throw (the length of the palm rather than across); the hand at the rear of the cord with at least one finger behind the binding. Below are three commonly used grips (Stander, 2006, p.1) Stander (2006) discusses the throw of a right handed athlete. The thrower should avoid: · A tensed grip on the javelin · Jumping upwards in the final strides · More than one cross step · Frontward facing shoulders during the pull phase · Bending at the hips allowing the core to bend forwards · Taking the javelin off its throwing line · Throwing from around the side of the body (Stander, 2006, p.2) The thrower should aim to: · Run straight during the approach · Hold body weight over the rear leg · Keep a straight throwing arm during the pull phase with an upward facing palm · Keep elbow along the line of throwing direction · Keep the javelin pointing in the direction of the throw (Stander, 2006, p.2) The approach – The javelin is carried at head height, arm bent, and elbow pointing forward. A relaxed grip, wrist, elbow and shoulder lead to a natural running action with high hips and shoulders facing forwards. The javelin is roughly parallel to the ground as the approach speed accelerates to the optimum speed (Stander, 2006, p.3). Step 1 and 2 – Move the javelin to the rear, over the right shoulder until the arm is straight and at shoulder height with the palm facing upwards. Accelerate ahead of the javelin instead of pushing the javelin back to maintain the approach speed. Rotate the shoulders to line up with the direction of the throw with hips remaining forward (as much as possible) to maintain approach speed (Stander, 2006, p.3). Step 3 – The tip of javelin is close to the athlete’s head with the point around eye level (eyes facing forward in direction of throw) (Stander, 2006, p.3). Step 4 (Drive) – A long, flat step to prepare for the powerful throw. The trunk leans back to allow for a long, delivery pull of the throwing arm. The right foot (circled) touches the ground heel first, on the outside edge, slightly in front of the hips and shoulders (still in line with direction of throw). Folding the left arm across the chest (rather than pointing in direction of throw) keeps the chest muscles relaxed. The right arm is still at full stretch with closed wrist and upward facing palm, javelin still at eye level (Stander, 2006, pp.3-4). Step 5 – Bringing the left leg forward puts the body in the power position. The right leg drives the body forwards and upwards. The straight left leg lands flat and pointing forward. Weight is transferred and accelerated through the hips. The free arm remains relaxed ahead of the body and throwing arm remains extended (Stander, 2006, p.4). The power position – · Body is arched · Head faces direction of throw · Shoulders and javelin parallel · High throwing hand, palm facing upward, wrist closed · Left leg forward and straight · Slightly bent right leg · Chin is vertically in line with right knee and toes (Stander, 2006, p.4) The Throw – Weight continues to drive through the right leg over and hips over an extended left leg (for a high point of release). The right hip turns forward quickly, with chest and shoulders following. The right elbow follows and the arm is whipped over the shoulder in a rapid forward and upward motion. The launch occurs over the left foot. Release of the fingers causes the javelin to rotate clockwise creating stability during flight (Stander, 2006, pp.4-5). Recovery – Transfer weight over the left leg after delivery, keeping left foot on the ground. The right leg comes forward quickly after the release to prevent stepping over the foul line (Stander, 2006, p.5). Quantitative biomechanics of the javelin throw: The motion of an object (e.g. javelin) projected at an angle into the air is referred to as projectile motion (Blazevich, 2012, p.25). Release Parameters: Release speed The release speed (projection speed or horizontal velocity) has the most influence on the distance (range) a projectile covers (Valleala, 2012). An object will travel further with a faster projection speed. Range = horizontal velocity x flight time. (Blazevich, 2012, p.25) Take the object in FIG 3.1 – The flight time of the tennis ball is the same, whether the player throws it up and lets it hit the ground or hits the ball horizontally (applying horizontal velocity). (Blazevich, 2012, p.25) There is a correlation between release speed and throwing distance in 180 Finnish javelin throws reviewed between 2004-2012 (Valleala, 2012, p.7). Lower release speeds (metres per second - m/s) are associated with less distance travelled (metres - m) and higher release speeds with greater distance. Javelins with release speeds of approximately 25m/s varied in distance thrown between approximately 62m and 76m. Javelins thrown approximately 76m had release speeds between approximately 25m/s and 28m/s. These large ranges and variations suggest there are other important contributing factors to maximizing the distance of a javelin throw. The Release speed can be further broken down according to the steps and technique of the javelin throw. The run up/approach delivers a preliminary velocity for the javelin, before muscular acceleration, in the drive and throwing phases. The run up speed (approach speed) is usually highest at the start of the drive step and decreases after that (Valleala, 2009, p.4) When an athlete straightens their throwing arm in preparation for a throw, this is known as the pull. The pull begins in the final steps of the approach and is important to the development of young throwers (Valleala, 2009, p.16). There is a correlation between higher approach velocity (m/s) and throw distance (m) (Valleala, 2009, p.5). Release Angle The release angle (angle of projection) is another important factor affecting the distance a javelin will travel. As shown in Fig 3.2, an object projected at 90o will land back at its starting point (provided there is no wind), so its range is zero. An object projected at 0o doesn’t get airborne so its range is zero as well. A javelin projected at 45o has equal vertical and horizontal velocity and will give the maximum range if the release height and landing height are the same(Blazevich, 2012, p.26). A typical optimum projection angle in javelin is around 33o (Linthorne, 2013). A javelin with a faster release speed, requires a lower trajectory (Stander, 2006, p.5). Aerodynamic factors: Wind Air resistance is usually very small and can be disregarded when examining heavy projectiles over shorter distances such as a shot put (Blazevich, 2012, p.25). The javelin is a long (women’s 2.2m up to men’s 2.7m), light (women’s 600 grams to men’s 800 grams) implement (Stander, 2006, p.1), and can affect the distance and direction of a throw. As athletes will usually be throwing under similar or the same conditions in competition, wind is not a large contributor to the outcome of an event. Strong headwinds require a lower angle of release and strong tailwinds require an increased release angle (Stander, 2006, p.5). Gravitation Gravity affects objects with some vertical motion (1-90 degrees). Gravity effects the flight time of an object (See FIG 3.1 in release speed). If an object is thrown straight in the air (moving only vertically at 90 degrees), the projection speed will determine the height it reaches before gravity pulls it back to earth, accelerating at 9.81 m.s-2 (Blazevich, 2012, p.25). What training methods can be employed? It is important for training plans to be specific. Javelin is a speed-power event with a high technical demand. Throwing events need a high production of force over a very small amount of time (Young, 2002, p.2). As the speed of release is the most important factor in a javelin throw, boosting the release speed gives an athlete the best chance of success. Power for an overhead throw is largely produced through leg extension, hip rotation and trunk flexion accounting for more than 50 percent of force in a standing overhead throw (Young, 2002, p.3). Highly skilled javelin throwers use an acceleration-deceleration system of movement where they accelerate into the throwing motion then radically decelerate to transfer energy (Young, 2002, p.3). A few specific examples for javelin preparation according to Young (2002, pp.2-9): · Axe chop – develops the stretch reflex contraction and arm strength, at the same time as flexibility in the shoulder girdle, pectoral and upper back muscles. The athlete should engage the whole body and focus on the whip-like action. The athlete swings axe/hammer over the head down to knee height hitting surface, letting the weight of the axe/hammer stretch the body on the back swing. · Bungee hip-snaps – to strengthen the core, develop an explosive hip drive and increase flexibility in the back and shoulders. A thera-band/bungee cord is attached to a fixed object. The athlete assumes the power position; the thera-band is taut when the throwing arm is at full extension behind the thrower. The athlete performs a half standing throw accentuating good hip and leg drive, and trunk and shoulder rotation. · Resisted approach runs – to develop acceleration. Using a weight vest or parachute, an athlete performs their run up as they would in a competition accelerating to the point of deceleration (during the throw). The Answer: An athlete can maximize the distance of a javelin throw by: A thorough technical knowledge of the movements and understanding how to break the movement down in to individual, sequential steps – athletes and coaches can make qualitative changes to individual parts of the skill and apply biomechanical principles to an individual athlete. Training – using biomechanical knowledge to train specific elements of the throwing action/sequence. Increasing the speed of release – if all other variables remain the same, an increase in release speed will increase the distance of the throw. Increasing the speed of any action of the throw (as long as it does not adversely affect the throw) will increase the speed of release. Increasing approach speed - high, but optimal running speed at point of release and a fast transfer from drive foot to planted foot during throwing phase (Valleala, 2009, pp.4-11). Lengthening and increasing the speed of the pull - A longer pull distance is associated with a higher release velocity (Valleala, 2009, p.16). Shorten recovery distance – an athlete that can stop quickly after a throw, can release the javelin closer to the foul line therefore adding that distance to their throw. Find the optimum angle of projection – this is between 30o and 36o with a faster release speed requiring a lesser angle of projection (Stander, 2006, p.5). How else we can use this information: Applying biomechanical knowledge to increase the distance that an athlete can throw a javelin is transferrable between athletic events and sports where projectile motion takes place. The principles of maximizing the javelin throw apply to other throwing events. In all throwing events the speed generated decreases as the projection angle increases (Linthorne, 2013). The optimum angle is always less than 45o and differs between athletes. The human body is a projectile in the long jump. The take off speed of a jumper decreases as the take off angle increases (Linthorne, 2013). Using qualitative measures (e.g. examining and making changes to the technique of a thrower) and quantitative measures (e.g. finding a correlation between projectile velocity and displacement) are skills that can transfer improving aspects of any physical activity. References: Blazevich, A.J. (2012) Sports Biomechanics, The Basics, Optimising Human Performance, 2nd Edition, Bloomsbury, London Linthorne. N. (2013) Optimum Angles of Projection in Throws and Jumps, CoachesInfo.com, University of Sydney, Australia Martini, F., Ober, W.C., Nath, J.L. (2011) Visual Anatomy and Physiology, Pearson Higher Education, Sydney Schmidt, R.A., Wrisberg, C.A. (2008) Motor Learning and Performance, A Situation Based Learning Approach, 4th Edition, Human Kinetics, South Australia Stander. R. (2006) Javelin Throw, Athletics Omnibus, Boland Athletics, Athletics South Africa, Houghton www.bolandathletics.com/5-13 Javelin Throw.pdf (cited 12/4/2013) Valleala, R. (2009) Biomechanical Factors of Throwers Actions in Javelin, World Javelin Conference Kuortane 9-11/10/2009, KIHU Research Institute for Olympic Sports Jyvaskyla Valleala, R. (2012) Biomechanics in Javelin Throwing, KIHU Research Institute for Olympic Sports Jyvaskyla, 2nd World Javelin Conference, Kuortane, Finland 7-9/11/2012, www.kihu.fi/tuotostiedostot/julkinen/2012_val_biomechani_sel72_42228.pdf (cited 13/4/2013) Viitasalo, J. (2011) Biomechanics in javelin throwing with special reference to feedback for coaching, KIHU Research Institute for Olympic Sports, Jyvaskyla Finland Young, M (2001) Developing Event Specific Strength for the Javelin Throw, Louisiana State University, http://www.elitetrack.com/article_files/javstrength.pdf (cited 11/4/2013) Young, M. (2002) Preparing for the Specific Neuromuscular and Biomechanical Demands of the Javelin Throw, Unites States National Throw Coaches Association, www.nationalthrowscoachesassociation.com/Forms/javelinthrowbiomechanics.pdf (cited 11/4/2013)