1. The Biomechanics behind Soccer Throw-Ins
By: Omar Khan

2. Purpose
To understand the biomechanics behind different styles of throw-ins.
To see the relative contributions of different muscle groups to the force generated from a throw-in.
To determine whether or not a full-motion throw-in is worth the effort or not.

3. Why Throw-Ins?
They are a very important part of soccer, despite having to use hands.
Having a good thrower can become a huge advantage for your team.
I’m weak…

4. Different types of Throw-In
Purely Arm Throw-in
Arched Back Throw-in
Run-up Throw-In
Flip Throw-In

5. Arm Throw-In

6. Arm Throw-In: Muscles involved

7. Fast-twitch muscle fibers
Generate significant amount of power

9. Kinematics: Arm Throw-In
Tan-1(1/1.2)= 39.81˚
13.8 m assuming constant velocity (windy day)

10. Divide by 10 on the values

11. Force: Arm Throw-In F=ma Mass of 2 Arms= 8.20 kg Mass of Ball= 0.42 kg

12. Arched-Back Throw-In

13. Arched-Back Throw-In: Muscles Involved
Erector Spinae

14. Back Throw-In, Position (Ball)

15. Kinematics: Arched Back Throw-In
Tan-1(1.8/2.0)= 42.0˚
Distance Travelled: m

19. Forces: Arched-Back Throw-In
Mass of 2 Arms= 8.20 kg
Mass of Ball= 0.42 kg
Mass of Torso= kg (Assume 45% of body mass)
(20.94)(8.62)= 180.5N
(2.645)(36.81)=97.4N
Total Force= N

20. Run-up Throw-In

21. Components of Run-up Throw-In
Momentum Generating Steps
Skip step
Stride
Jump step
Force Generating Steps
Lunge
Arched-Back
Arm motion

22. Run-Up Throw-In: Muscles Involved

24. Kinematics: Run-up Throw-In
Tan-1(2.0/2.0)= 45.0˚
25.8 m assuming constant velocity (windy day)

28. Force: Run-Up Throw-In
Mass of 2 Arms= 8.20 kg
Mass of Ball= 0.42 kg
Mass of Torso= kg (Assume 45% of body mass)
Mass of Body= 81.8 kg
(24.4)(8.62)= N

29. Force cont.
(6.75)(36.81)= N
Total force= N

30. gurrilla

32. Impulse: Run-up Throw-In
Momentum in x direction= mv
(81.8)(2.493)= 203.9
∆Momentum= impulse
= N*s
Momentum in y direction= mv
(81.8)(-1.080)=-88.3
0-(-88.3)=88.3 N*s (this process occurs over 0.6s)
Force applied by legs= N
Force gained by legs= N
Conservation of momentum= 487N close to predicted 457N

33. Is it worth it? 277-211=66 20.67-13.8=6.87 66/6.87=9.61 N/m
=195
=5.13
195/5.13=38.0 N/m
Not worth it

34. Further Questions
What injuries can arise from over-straining in throw-ins?
What are the consequences of raising your back leg in a throw-in?
How much force can be generated with a flip-throw-in?
What is the ideal angle for the trajectory of the ball?
How can we limit the assumptions made for this project?
Further studying the projectile motion of the ball.
How does hand positioning affect ball movement?

36. Flip Throw-In

37. References