Kicking & Moment of Inertia

Question 1

6 Phases of kicking

Answer 1

1. Approach angle (Preparation)
2. Plant foot forces (Preparation)
3. Swinging limb loading (Retraction)
4. Hip flexion and knee extension (Action)
5. Foot to ball contact (Follow-through)
6. Follow-through (Follow-through)

Question 2

Factors affecting the preparation phase

Answer 2

Approach angle

Number of steps

Length of steps

Speed

Position of supporting leg

Question 3

Factors to be considered during approach

Answer 3

Optimum angle is anywhere between 30° and 45°

Inculcation of the upper body to enable the max shank velocity

The approach tends to be curved with 2 to 4 steps; at about 3 to 4 m/s

Standing leg 30-35cm to the left of the ball. 5-10cm behind the ball

Forces at play are lateral and posterior (braking)

Question 4

What is the parallel axis theorem

Answer 4

The moment of inertia is reduced because the shank and foot segments are closer to the hip joint. This can be used to calculate the legs moment of inertia.

The mass’ will be constant but the distances from the pivot points will change

Question 5

What does the Radius of rotation equal

Answer 5

The distance from pivot point to centre of mass of the object/person

Question 6

What is an advantage of a double pendulum?

Answer 6

It increases the velocity of the distal segment while retaining a low moment of inertia.

The lower limb has two ‘stops’ at the knee joint.

Question 7

What is the role of extensor muscles?

Answer 7

Prevent hyperflexion

Question 8

What is the role of flexor muscles?

Answer 8

Prevent hyperextension

Question 9

Role of Quadriceps during kicking?

Answer 9

Prevent hyperflexion (ECC)

Assist knee extension (CON)

Question 10

Role of Glutes during kicking?

Answer 10

Involved in retraction (CON)

Decelerating flexion (ECC)

Question 11

Role of Hamstrings during kicking?

Answer 11

Involved in retraction (CON)

Decelerating knee extension (ECC)

Question 12

Role of Iliopsoas during kicking?

Answer 12

Hip Flexion (CON)

Question 13

According to Lees et al. (2010), more experienced players demonstrate a “tension arc” when kicking a football. Which neuromuscular principle enhances performance due to the tension arc and during which phase of the kick is this arc developed?

Answer 13

The tension arc utilises the stretch shortening cycle and is developed during the retraction phase