BTEC National Diploma in Sport & Exercise Science

Unit 16: BIOMECHANICS Assignment One

‘Initiation and Development of Movement’

Task 1 –

Below is a picture of a Javelin thrower, I am about to discuss the muscle actions, action at the joints, action of the limb segments and the muscle contractile velocity and force.

Class Notes

In the diagram you can see that the body is working at the right and left wrist, the right and left elbow, the right and left shoulder, the spine, the hips, the right and left knees and the right and left ankles. The muscles actions taking place at the:-

The right wrist is in supination because the palm of the hand is facing upwards, the wrist is also extending due to the extensors contracting in a concentric manor while the arm is fully extended so the flexors will relax. The right elbow is also extending, the angle between the radius and ulna becomes closer to 180 degrees, this means that the bicep will eccentrically contract whilst the tricep concentrically contracts making the bicep longer and the tricep longer. The right shoulder is in a phase of horizontal abduction because it is placed out to the side of the body so the deltoid contract concentrically and the pectoralis major contracts eccentrically. The reason the right arm is extended is to get as much angular force into the throw as possible, this is because the more force the javelin thrower can apply then the further the javelin will go.

The left wrist is in pronation so the palm of the hand is facing towards the ground, this is means that the extensors and flexors are relaxing because there is no need for them at that particular moment. The left elbow is flexing due to the concentric contraction of the bicep whilst the triceps is in eccentric contraction, the elbow is in extension because the angle of the humerus and radius is decreased. The right shoulder is in a state of horizontal adduction because the arm is facing infront of the body. The deltoid will contract eccentrically and the pectoralis major will contract concentrically in order to do this. The reason the left arm is mainly in the phase of flexion is to balance the body out so that when the javelin thrower releases the javelin he will not fall to the floor and the javelin will go in the direction it is supposed to.

The Hips are in horizontal and lateral rotation because they are facing to the right of the body to try to get momentum into the throw, this is because the right latissimus dorsi is contracting concentrically with the rectus abdominis and the left latissimus dorsi is contracting eccentrically. The right serratus anterior also contract concentrically while the left serratus anterior contract eccentrically, this cause the hips to rotate towards the right of the body. The hips also force the right femur to flex because the biceps femoris, gracilis, semitendinosus and semimembranosus are all contracting concentrically while the vastus lateralis, rectus femoris and vastus medialis are contracting eccentrically. The left femur is extending because the vastus lateralis, rectus femoris and vastus medialis are contracting concentrically and the biceps femoris, gracilis, semitendinosus and semimembranosus are all contracting eccentrically. The spine is arching away from the body so we know that is in extension, the muscles that make this happen are the erector spinae and the bottom of the lattisimus dorsi. The erector spinae muscles are extending so they are contracting eccentrically while the lower back muscles which are the latissimus dorsi are shortening so they are contracting concentrically which forces the spine to extend. The reason the spine extends is because the body is creating more force, when the thrower releases the javelin he will use the back muscles also to propel the body forwards.

Join now!

The right knee is in a state of flexion and the right ankle is in plantarflexion, this is because the gastrocnemius and soleus are contracting concentrically whilst the tibialis anterior, tibialis posterior and the extensor digitorum longus are contracting eccentrically. This causes the ankle to be up on the toes of the foot and the muscles that make the knee flex are the biceps femoris, gracilis, semitendinosus and semimembranosus are all contracting concentrically while the vastus lateralis, rectus femoris and vastus medialis are contracting eccentrically. The reason the right leg is flexing is so that the most potential force can be ...

This is a preview of the whole essay