Jumps

Question 1

Squat jump- explain how to execute the jump

Answer 1

• measure 90 degrees with goniometer
• get to 90 degrees
• minimum of 3 practice attempts
• hands on hips throughout entire jump
• face forwards
• no leg flicking
• count to 4 seconds, jump after 4
• no dipping

Question 2

what does dipping introduce in the squat jump?

Answer 2

the squat jump is measuring concentric performance therefore the dip will introduce an eccentric phase (elastic energy/ momentum into the jump)
- all elastic energy should be dissipated as heat with the 4 second hold

Question 3

what does the squat jump not utilise?

Answer 3

the stretch shortening cycle as the elastic energy or the utilisation of the SSC (going from eccentric to concentric rapidly is diminished)

Question 4

which jumps utilise the SSC?

Answer 4

drop jump and countermovement jump
-both jumps use the SSC
active eccentric (lengthening) of the muscle followed immediately by a concentric (shortening) contraction of the same muscle

Question 5

describe the length tension relationship?

Answer 5

the length tension relationship relates to the length and overlap of the sarcomeres (actin and myosin)
optimal LTR means the action and myosin can form more cross-bridges
-too short- the actin and myosin will butt/ overlap, halting the formation of cross-bridges decreasing tension
-too long- the actin and myosin are pulled away from each other so there is little interaction and minimal cross-bridges can be formed -no tension created!!!

Question 6

drop jump-explain how to execute the jump

Answer 6

• drop off the box- do not step or jump
• don’t look down-causes over rotation
• legs straight when jumping- minimal bend at the knees
• minimal contact time for maximum height-stiff legs
• land on balls of the feet (floor is lava)
• hands on hips

Question 7

which type of reactive strength does DJ utilise?

Answer 7

Fast reactive strength

• ability to produce force rapidly (eccentric to concentric rapidly)
• related to maximum speed rather than acceleration (CMJ)
• contact time of less than 200ms (0.2s)

Question 8

which type of reactive strength does CMJ utilise?

Answer 8

Slow reactive strength

• ability to augment the force from concentric contraction with additional energy stored from eccentric action
• how much force can they produce??
• acceleration rather than speed
• contact time more than 250ms (0.25s)

Question 9

how many practice jumps should be done?

Answer 9

minimum of 3 practice jumps

Question 10

what is the squat jump an indicator of?

Answer 10

concentric performance

-removes eccentric contraction (stored elastic energy) from the lengthening phase- dissipates as heat

Question 11

name some ratios for jumps?

Answer 11

EUR (eccentric utilisation ratio)
PSAP (pre-stretch augmentation percentage)
RSI (reactive strength index)