37_38_39- Kicking, Throwin, Backpacks!

Question 1

what is def between skilled and non skilled kickers

Answer 1

skilled kickers show sig less variability in velocity

Question 2

what is the angle of approach in a kick

Answer 2

usually diagonal (same foot velocity either way)

Question 3

do u want more/less GRF in soccer/punt

Answer 3

more GRF wanted in soccer kick compared to punt

Question 4

what does initiation of kicking start w

Answer 4

kicking limb knee flexed and hip extended (allows them to be eccentrically loaded in preparation for the forward movement of the limb into position to strike the ball)

Question 5

just before contact what happens w hams

Answer 5

flexion torque is applied to slow the limb

if done to early then less energy will enter the ball

Question 6

steps to kick from initiation

Answer 6

as the hip flexors act to swing the thigh forward and down the leg and foot remain in a fixed pos

as the thigh velocity decreases, the leg + foot accelerate due to knee extensors preparing to strike the ball

Question 7

what is linear velocity in the kick

Answer 7

more speed you get @ the top-> the more that trasfers down the chain

Question 8

at contact of kick is flexion or extension greater

Answer 8

at contact, flexion moment greater than extension moment to prevent hyperextension of the knee

Question 9

contact time w kick and velocity

Answer 9

longer you keep contact the more velocity you will create

Question 10

4 factors influencing ball velocity

Answer 10

1. foot velocity
2. rigidity of the limb at impact
3. Position of the foot relative to the ball
4. Ball inflation

Question 11

moment of inertia transfer with throwing

Answer 11

large segments that produce torque which accelerates smaller segments

-small segments have smaller amount of inter and therefore move with greater angular velocity

Question 12

what are the 6 accelerations of a throw

Answer 12

1. upper portion of body is flexed after being extended
2. trunk rotates about its longitudinal axis to pull throwing arm forward
3. humerus acts in conjunction w scapula as it flexes over 90 degrees
4. humerus int rotates
5. flex of wrist
6. Finger flexed

Question 13

6 phases of throw

Answer 13

wind up
stride
cocking
arm acceleration
arm deceleration 
follow thru

Question 14

stride foot work in throw

Answer 14

leg should be directly in front of other

Question 15

anterior sheer force
superior sheer force
compression force

(in N in throwing)

Answer 15

ant shear- up to 350
sup shear- up to 250
compression- over 1000

Question 16

recommended weight limit of backpack

Answer 16

10-15% of bw

most children exceeding

Question 17

how many students one strap it

Answer 17

20%

Question 18

why are children more susceptible to overuse syndrome w backpacks (2)

Answer 18

1. epiphysis made of cartilage which is susceptible to microtrauma
2. mm growth often does not keep up w bone growth causing mm tightness

Question 19

what is the best predictor of back pain w backpacks

Answer 19

fatigue

Question 20

biomechanics impacts of backpack loads (4)

Answer 20

1. stride length, cadence and speed decrease
2. increased lumbosacral and trunk angles
3. Decreased thoracic kyphosis
4. Increased contact area of foot and increased pressure leading to foot discomfort

Question 21

Trunk forward lean and backpack

Answer 21

more w backpacks

–associated w low back injiries; sig over 15% BW

Question 22

what % BW caused sig changes in craniovertebral angle

Answer 22

15%

Question 23

what are the palsies associated w backpack use

Answer 23

• weakness of mm supplied by supra scapular and axillary nerves
• sensory impairment of C5/6
• Recovery takes 3.5w to 3m

Question 24

blood pressure and vital capacity changes were seen at what % BW

Answer 24

as it reached 20% BW