Wilks Coefficient

The Wilks Coefficient or "Wilks Formula" is a coefficient that can be used to measure the strength of a powerlifter against other powerlifters despite different weights.

Equation

The following equation is used to calculate the Wilks Coefficient. The total weight lifted is multiplied by the Coefficient to find the standard amount lifted normalized across all body weights.

$Coeff\; =\; frac\{500\}\{a\; +\; b*x\; +\; c*x^2\; +\; d*x^3\; +\; e*x^4\; +\; f*x^5\}$

x is the body weight of the lifter in kilograms

Coefficients for "men" are:
a=-216.0475144
b=16.2606339
c=-0.002388645
d=-0.00113732
e=7.01863E-06
f=-1.291E-08

Coefficients for "women" are:
a=594.31747775582
b=-27.23842536447
c=0.82112226871
d=-0.00930733913
e=0.00004731582
f=-0.00000009054

Example

According to this setup, a male athlete weighing 320 pounds and lifting a total of 1400 pounds would have a normalized lift weight of 778.26, and a lifter weighing 200 pounds and lifting a total of 1000 pounds would have a normalized lift weight of 635.8. Thus the 320 pound lifter would win this competition. As you might have noticed the lighter lifter is actually stronger for his bodyweight, with a total of 5 times his own weight, while the heavier lifter could only manage 4.375 times his own bodyweight. The "Wilks Coefficient" credits heavier lifters with more points than lighter lifters, despite the lighter lifter totaling more for their bodyweight.

External links

*http://www.isu.edu/~andesean/wform.htm
*http://www.usapowerlifting.com/lifterscorner/wilks-kilo-men.shtml
*http://www.uwpf.com/wilks.asp?section=tec&title=Wilks+Formula