Biomechanics of the Football
Throw
Varun Patel
BIOL438
Professor Rome
Questions

What are the kinematics of a football throw (Does the elbow
or wrist have greater end velocity)?
◦ I will be analyzing physical quantities such as velocity, acceleration, torque
and force generated during a football throw.
◦ Most of these factors are essential to throwing the perfect spiral.

How does football throw compare with a baseball throw?
◦ We’ll take a deep look into the football throw and compare that with the
baseball pitch.

How does my ball velocity compare with professionals?
◦ Surely, professionals have greater control of their body movement and are
able to rotate body parts more rapidly to generate high velocities
◦ Some of it has to do with aerodynamics and ball spin.
Football Throw Fundamentals
Throw the ball in a half-circle motion to
increase centrifugal force on the ball.
 Rotation of the shoulders will generate
torque to speed up the ball.
 Ideal release point is ¾ way through the
acceleration phase
 Roll your fingertips off as you release the
ball – index finger should be the last to
touch the ball.
 Arms must form close to 90 degree angle.

4 Phases of the Football Throw
Early Cocking
 Late Cocking
 Acceleration
 Follow Through

Early Cocking
Planting of the quarterback’s rear foot
 Maximal shoulder abduction
 Internal rotation
 Ends when the ball is at shoulder height with the elbow pointing
back

Late Cocking
Ball at shoulder height moving upward
 External rotation of shoulder
 Ball posterior to the head

Acceleration
Full rotation of shoulders
 Snapping of the wrist
 Trunk and leg muscles send power to arms.
 Flexion to extension of the elbow – key!

Follow Through
Arm in horizontal position
 Hand pronated, shoulder abducted, wrist flexed

Muscles Activated during Throw
Muscle Groups II
Rotator Cuff
muscles active
throughout entire
motion (Stabilizers)
Subscapularis and Pecs
active most during
acceleration and
follow through
(accelerators)
The Role of Joints
Elbow produces valgus torque– caused by upper torso
movement and shoulder rotation – helps accelerate the ball. Too
much torque (overload) can result in serious injuries.
 Glenohumeral joint – ball and socket joint connecting scapula
and humerus. Plays a role in arm cocking (in preparation for
acceleration). More flexible joints allow greater range of
motion.

Personal (Imperfect) Demonstration
Ball Movement
 Release
 Acceleration phase begins
Calculations

Assumptions: constant acceleration, no air resistance or friction, force
acting perpendicular to moment arm.

Y-velocity of ball = 2.1 m/s

X-velocity of ball = 9.7 m/s

Total velocity of ball upon release = 9.92 m/s

Time of acceleration phase = 0.45 seconds

Force on the ball = ma = (.51 kg)(22.04 m/s^2) = 11.24 N

KE at release = (½)mv^2 = (½)(.51 kg)(9.92 m/s)^2 = 25.09 J

Change in PE = mgh = (.51 kg)(9.8 m/s^2)(.23 m) = 1.15 J

Power = Fv = (11.24 N)(9.92 m/s) = 111.5 J/s

Work done = Change in KE + PE = 26.24 J

Ball momentum after release = mv = (.51 kg)(9.92 m/s) = 5.06 kg*m/s

Torque on the ball = Fr = (11.24 N)(.304 m) = 3.42 N*m
Elbow and Wrist Movement
Elbow
Wrist
•Wrist reaches a higher speed than elbows
•The wrist and ball are the end products of the rotational and linear
energy provided from the trunks to the upper body
•Wrist has a longer range of motion and more time to accelerate
•Elbow needs to generate torque (more-so than speed) to propel the
wrist and ball forward
•Top wrist speed = 5.1 m/s
•Top elbow speed = 3.3 m/s
Comparison to Baseball
In baseball…
◦ Greater rotational velocities of arm/trunk
◦ More elbow extension necessary.
◦ Higher shoulder rotation angular velocity
◦ Faster kinematics (more force on the ball, faster velocity,
greater power relative to previous calculations)
 In football…
◦ Rotate shoulders sooner to generate more power
◦ Stand more erect – limits the contribution of lower body
◦ Greater elbow flexion to compensate for lower speeds

Comparison to Professionals
QB
Average Speed of Throw
Brett Farve
66 mph
John Elway
61 mph
Tom Brady
70 mph
Me
22 mph 
Why…?
•NFL QB’s have greater
rotational velocity and transfer
of momentum
•Better hand and foot
placements
•Can throw better spirals
Common Injuries
Common Injuries include…
•
Rotator cuff contusion
•
Shoulder dislocation
•
Sternoclavicular joint separation
Most common injury: Acromioclavicular Sprain
•Sprain of the AC ligament (intact)
•Disruption of AC ligament
Injuries II
UCL Injury
Tear in the ulnar collateral ligament (connects ulna to humerus):
•As a result of overload and too much torque supplied by the
elbow.
Ball Spin and Aerodynamics
QB must balance forward momentum of ball with forces of
gravity and drag.
 Forces of wind produce a torque that counterbalances gravity –
keeps the ball in the air. This torque acts perpendicular to the
direction of angular momentum
 Wobble occurs as ball spins slightly off axis

Summary of Findings

What are the kinematics of a football throw?
◦ Ball experiences almost 11.2 N of force and I do approximately 26 J of
work.
◦ Elbow velocity is slower than wrist and ball velocity

How does a football throw compare to a baseball throw?
◦ Baseball throw has greater rotational velocity and greater elbow extension.

How does my throw compare to that of professionals
◦ Professional quarterbacks can throw at speeds 3x than mine
◦ This is because they are able to better rotate their bodies and impart
greater energy to the ball (along with spin)
Future Studies on Football Throws
Is the speed of a football throw more dependent on
technique or arm/shoulder strength?
◦ Ex: Bodybuilder with no football experience vs. scrawny
high school QB with years of experience
 Does finger placement affect the ultimate speed of the ball?
◦ Ex: How far the fingers are spaced out
 What are the best ways to prevent injuries that quarterbacks
often suffer?
◦ Ex: Stretching, better padding, etc
 Research Methods
◦ Electromyography to detect muscle recruitment
◦ 3D imaging software

References
"Baseball vs. Football." American Sports Medicine Institute. Web. 10 Apr. 2012.
<http://www.asmi.org/asmiweb/research/usedarticles/baseballvsfootball.htm>.
Fleisig, G., and R. Escamilla. "Biomechanics of the Elbow in the Throwing
Athlete."Operative Techniques in Sports Medicine 4.2 (1996): 62-68. Print.
Garrett, William E., and Donald T. Kirkendall. Exercise and Sport Science.
Philadelphia: Lippincott Williams & Wilkins, 2000. Print.
Kelly, B. T. "Shoulder Injuries to Quarterbacks in the National Football League."
American Journal of Sports Medicine 32.2 (2004): 328-31. Print.
Kibler, W. B., A. D. Sciascia, T. L. Uhl, N. Tambay, and T. Cunningham.
"Electromyographic Analysis of Specific Exercises for Scapular Control in Early
Phases of Shoulder Rehabilitation." The American Journal of Sports Medicine36.9
(2008): 1789-798. Print.

Questions?