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)