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Throwing a cricket ball

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James Dunbar

on 9 September 2014

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Transcript of Throwing a cricket ball

By James Dunbar
Throwing a cricket ball
The skill I have chosen is throwing a cricket ball. Firstly I will talk about the shoulder anatomy, then more down through the arm, discussing the elbow and wrist anatomy whilst performing my skill. The shoulder joint in conjunction with the elbow joint and the ulnar and radial bones of the forearm, are operated to create a powerful lever to perform my skill. The ability of my shoulder to rotate is essential to throwing a cricket ball. The components of the shoulder joint include the humerus; the long bone of the upper arm that is a part of the elbow and shoulder joints, the scapula; positioned on the rear of the shoulder on the upper back, the clavicle; aligned between the neck and the out limit of the shoulder and finally the sternum; which supports the opposing end of the clavicle from the shoulder. All of the shoulder bones have articular cartilage covering the head of the bone that comes into contact with another bone. This articular cartilage reduces the degree of friction created by the two bones rubbing against each other, it also provides a measure of cushioning between the bones. The glenohumoral joint is the largest joint in the shoulder, it is the part of the shoulder that is most commonly described as the shoulder joint. This joint is a ball and socket joint as it is where the head of the humerus and the portion of the scapula known as the gleniod meet, this permits the shoulder to rotate freely. The joint contains a small quantity of synovial fluid that assists in the movement of the joint. The muscles involved in the shoulder whilst performing my skill are: Biceps, Triceps, Deltoids, Trapezius and Latissimus Dorsi. The components of the elbow joint are distal end of the humerus in the upper arm and the proximal ends of the ulna and radius in the forearm. Like all other synovial joints, a thin layer of smooth articular cartilage covers the ends of the bones that form the elbow joint. The joint capsule of the elbow surrounds the joint to provide strength and lubrication to the elbow. Slick synovial fluid produced by the synovial membrane of the joint capsule fills the hollow space between the bones and lubricates the joint to reduce friction and wear. Being a hinge joint, the only movements allowed by the elbow are flexion and extension of the joint and rotation of the radius. The range of motion of the elbow is limited by the olecranon of the ulna, so that the elbow can only extend to around 180 degrees. Flexion of the elbow is limited only by the compression soft tissues surrounding the joint. The muscles involved in the elbow whilst performing my skill are: Biceps, Triceps, Wrist Extensors and Wrist Flexors. The components of the wrist joint are the Radius, Ulna, Carpals, Metacarpals and Phalanges. Like any synovial joint, the capsule is dual layered. The fibrous outer layer attaches to the radius, ulna and the proximal row of the carpal bones. The internal layer is comprised of a synovial membrane, secreting synovial fluid which lubricates the joint. The wrist is an ellipsoid type synovial joint, allowing for movement along two axes. This means that flexion, extension, adduction and abduction can all occur at the wrist joint. The muscles involved in the wrist joint are: Wrist Extensors and Wrist Flexors.
Newton's Laws
Newtons 1st Law

All things at rest want to stay at rest, all things in motion want to stay in motion (unless acted on by an external force). A cricket thrower must supply the force required to bring the ball from rest to motion. The inertia of the ball will try to oppose the throwers attempts to accelerate the ball and therefore he must provide a force that will overpower the ball's resistance. Another form of Newtons Law of Inertia is the ball being acted upon by an unbalanced force which in this case is usually the wicket keepers gloves. The ball will remain in motion unless it is acted upon by the wicket keeper. An example of this is the the bowler throwing the ball, if the ball is not intercepted by the batsmen or the wicket keeper the ball will keep going. But the wicket keepers gloves, an unbalanced force, brings the ball into play demonstrating the law of Inertia.
Skill Learning
Although this video is based on a baseball throw it still applies to cricket and is very similar to a cricket ball throw, so the same principles in this video apply to my activity
Newtons 2nd Law

F = ma, force = mass times acceleration. The force required to accelerate the ball is proportional to the magnitude of the acceleration, and this proportionality constant is equal to the mass of the cricket ball. Even though the mass of a cricket ball is relatively small when compared to a human body, the power of the throw is small compared to the speed of the ball when thrown, so he needs to generate the acceleration of the ball in his throwing action and apply a fairly large force providing a fairly large acceleration in a short period of time. For cricket this means that the more force applied whilst the ball is thrown the further it will go.
Newtons 3rd Law

For every action, there is an equal and opposite reaction. There are a few things that have reactions forces in cricket it starts of with the ball bouncing of the grass after being thrown, their is an reaction force from the ground to the ball. A second example is a reaction force is when the ball makes contact with the bat, the bat is providing an equal or greater reaction force to drive the ball. Thirdly is the force of the ball being caught, (in this case by the wicket keeper or another fielder). When the ball is caught there is a reaction force from your hands onto the ball.
Anatomy Videos
Forces Whilst Throwing
- Muscular
- Gravitational
- Aerodynamic
- Inertia
The interrelationships between the principles start when I think about how I will perform my skill of throwing a cricket ball. How will I learn this skill and how will I become better at performing my skill? By filming my throwing action on Ubersense I was able to film my throw in slow motion and compare it with a professional cricket player's throw and see they differences in our techniques. This gave me useful feedback in which to construct practice sessions to improve my skill. The skill of throwing a cricket ball can be broken down into phases. The preparation phase or loading phase, the action phase followed by the follow through phase. I found the learning of the skill easier if I broke the skill into my subroutines. The plant of my stabilising foot, the shoulder rotation and finally the projection of the cricket ball from my hand. I concentrated on the rotation of the shoulder joint to get the maximum range of motion and create maximum torque before uncoiling and throwing the cricket ball at around 45 degrees. This seemed the optimal release angle to get the best distance I discovered from my research. However this is assuming that the ball is thrown and received at the same height. As I am not as flexible as I am during the cricket season, my range of motion is decreased and hence my maximal force is decreased resulting in a smaller distance thrown compared to at the end of the cricket season, where my shoulder is more flexible as I am throwing frequently. From my video footage on Ubersense I was able to determine that my release was close to 45 degrees but my follow through was restricting how far the ball traveled. I was not bringing my front arm high enough or stepping into or out of my throw as well as I could. I compared my videos to those of Michael Stevens, Curtis Loose and Paddy Leckie and they were quick to give me constructive criticism and give me tips to improve my technique. I found that the muscles involved in my skill and how they worked to get the maximum effect (propelling force) to the cricket ball was important for me to understand if I wanted to improve my skill. Performing my skill for me started in my legs and finished at the release point which is my hand. To get the maximum force into my throw I had to sequence the muscles from the large muscles of my legs (quadriceps) and then the muscles in my upper arm (deltoid, triceps) and finishing with the small muscles in the lower arm (wrist extensors, wrist flexors). With each muscle force building on the preceding muscles we get the concept of summation of forces. The momentum built up prior to the release is then transferred to the cricket ball, momentum is a product of the cricket balls velocity and it's mass. To get the maximum velocity I had to think about the muscles involved. If I was stronger then I could have possibly created more force and a greater velocity resulting in a greater acceleration to the cricket ball. If I was to train in my skill again I will involve strength training as well, as this would assist in throwing a larger distance.
"The above ideas are further detailed clearly in my Anatomy section. Although I have not mentioned my leg involvement whilst performing my skill, until now I believe it was necessary to discuss leg involvement in my Interrelationship section."
Photos of my Skill
Prep Phase
Action Phase
Action Phase
Follow Through
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