The Biomechanics of Punching

Vincent Bradbury Andrew Calogero

John FilostratCharles Henkel

Kevin HollyMary-Anne Nguyen

Outline

Background Materials and Methods

Accelerometer Foot-force plates Video Analysis

Results Analysis Conclusion

Background Martial arts have been

practiced for hundreds of years The key to success in martial

arts is to master proper techniques

Our study will provide a focus on the effectiveness of using proper technique while performing a rear-cross punch   

Materials Wood frame & sand bag Accelerometer

Context Logger Foot-Force Plate

Kistrel Piezoelectric Force Plates

BioWare Software Package A-D hardware and Computer

Video Analysis iPhone Reflective body markers Background length markers

http://www.mobilewhack.com/wp-content/images/2009/02/iphone_video.jpg

Method Proper technique

subject stood on the foot-force plates on the balls of his feet and front hip pointed toward the bag

Punching by twisting the hips and shoulders forward while pushing off of the back-foot to drive the fist forward

Improper technique subject first stood on the foot-

force plates with flat feet and hips facing the bag

Punched the bag with full force using his shoulder

Results: Accelerometer

Analysis: AccelerometerPunch # Improper 1 Improper 2 Proper 1 Proper 2

Impact Force N 249.393 272.3341 401.1037 251.5989

Results: Foot-Force Plates

Analysis: Foot Force Plates Peak of the total ground force

reaction was calculated by finding the instantaneous vector forces of the Fx, Fy, and Fz

Max Rx Max Ry Max Rz Max Lx Max Ly Max Lz

proper 1 30.20498 81.17479 556.361 131.8171 76.15867 544.8445

proper 2 77.16128 91.67496 495.637 117.624 63.17786 467.3839

improper 1 28.09289 71.6343 470.6215 95.60793 54.62115 590.1548

improper 2 26.21577 54.16175 566.4687 113.0273 101.229 607.615

Results: Video Analysis

Analysis: Video Analysis Initial velocity after the punch

Mgh=0.5mv^2 V=sqrt(2gd)

Distance traveled by the bag Arc length=( /360)2* *radius ,where is the θ π θ

angle in degrees

Trial delta t (s) Theta (degrees) scale (1:6") height, h (m) radius (m) arc (m) V1 (m/s)Improper 1 0.333 32 1.02245 0.103169 0.38612538 0.215543767 1.42273532Improper 2 0.367 54 1.0462 0.240118 0.414083909 0.390067043 2.17051035

Proper 1 0.3 46 1.10565 0.208773 0.457682579 0.367264843 2.0238889Proper 2 0.4 51 1.0462 0.243243 0.440678648 0.392057104 2.18458867

Conclusion Accelerometer

Improper technique has an average force that is a bit lower than the average proper punch forces

Maximum improper force is actually greater than the minimum proper force

GRF that was observed during this strike may also show a smaller reaction for from the punch

Foot force plate More twisting involved during the proper

technique Proper technique enhances the force available to

give off in the x-y plane based on Newton’s third law of motion.

Video analysis Video recorder captured each punch at an angle

not perpendicular to the plane of action Scaling every dimension to the six inch reference

marking behind each shot To reduce error in a hypothetical duplicate lab, a

camera stand and highspeed camera faced directly into the plane of action