1. Compare the SJ and CMJ. Explain the difference in terms of the stretch-shorte
ID: 3509679 • Letter: 1
Question
1. Compare the SJ and CMJ. Explain the difference in terms of the stretch-shorten cycle.
2. Compare the DJ and the CMJ. You might find varied results of the DJ, that is, some individuals may jump higher, some lower, and some the same. Explain these results in terms of the stretch-shorten cycle, velocity of eccentric contraction, and force of landing.
3. Compare the pre-stretch CMJ and the post-stretch CMJ. Explain your findings in terms of tissue properties following stretching.
Jump Height Data Table
Countermovement Jump
(cm)
Squat Jump
(cm)
Drop Jump
(cm)
Post-stretch Countermove Jump (cm)
Student 1
12
11
9
10
Student 2
18
17
18
18
Student 3
18
21
19
19
Student 4
20
18
18
19
Student 5
26
26
27
27
Jump Height Data Table
Countermovement Jump
(cm)
Squat Jump
(cm)
Drop Jump
(cm)
Post-stretch Countermove Jump (cm)
Student 1
12
11
9
10
Student 2
18
17
18
18
Student 3
18
21
19
19
Student 4
20
18
18
19
Student 5
26
26
27
27
Explanation / Answer
1:- CMJ are almost always better than the SJ.The diffrence in performance may primarily related to greater uptake of muscle slack and the build up of stimulation during the counter movement in CMJ.Elastic energy also has contribution in enhance CMJ performance.The counter movement allows greter joint movements at the start of push off.so joint movement are greater over the first part of range of joint extension in CMJ so that more work could be produced than in SJ.counter movement allows the muscle to build up a high level of activ state and force before the start of shortning so that they were able to produce more work over the first part of their shortening distance.
Ans 2: stretch shortening cycle has 2 components one is the active stretch called eccentric contraction and then followed immediately by the 2nd one called concentric contraction. In drop jump first there is landing where the kinetic energy is converted into potential energy and then the eccentric contraction which furthur adds in the potential energy which leads to more work and then immediately followed by the up jump which is the concentric contraction.The velocity and force of landing are higher in drop jump than the CMJ.thus it usually gives higher results but there is individual variation so results vary.
Ans 3:-prestretch is the depth the athlete will move down during the short CMJ.the bending of knees and then applying force on land to jump are the part of pre stretch and all the events upto landing after prestretch are post stretch CMJ.
At tissue level that is muscle due to sodium and calcium ion there is depolarization of the muscle cell that is sacrcomere that leads to contraction of the muscle and give a thrust for jump.when the body is in air the channel closes and the muscke are in relax mode.again after landing the stimulation by the landing force causes muscle to contact to counterbalance the landing force and maintain the body posture.
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