[equation]
\begin{align}
i\!n\!t \left(r\!e\!p\!s, R\!P\!E\right) &= \left(A \cdot R\!P\!E + B\right)\left(C + D \cdot r\!e\!p\!s + E \cdot r\!e\!p\!s^2 + F \cdot r\!e\!p\!s^3\right)\\
R\!P\!E \left(r\!e\!p\!s, i\!n\!t\right) &= \dfrac{1}{A} \left(\dfrac{i\!n\!t}{C + D \cdot r\!e\!p\!s + E \cdot r\!e\!p\!s^2 + F \cdot r\!e\!p\!s^3} - B\right)
\end{align}
[/equation]
where
[equation]
\begin{align}
A &= 0.033056 \\
B &= 0.67374 \\
C &= 102.15 \\
D &= -3.7133 \\
E &= 0.14921 \\
F &= -0.0071171
\end{align}
[/equation]
source
H\left(\boldsymbol{r\!e\!p\!s},\boldsymbol{i\!n\!t}\right) = \sum_{n=1}^N r\!e\!p\!s_n \left(\frac{100}{100-i\!n\!t_n}\right)^2
[/equation]
[math]H[/math] is an arbitrary measure of accumulated fatigue for multiple sets of the same exercise, where each set is assumed to stop 2-3 reps short of failure, for purposes of choosing how much volume to include in a program.
[math]N[/math] is the number of sets
[math]r\!e\!p\!s_n[/math] is the number of reps of set [math]n[/math]
[math]i\!n\!t_n[/math] is the intensity, as percent of e1RM weight used for set [math]n[/math]
An [math]H[/math] value of 200 for a given exercise would be a "light" workout, easy to recover from for most lifters.
An [math]H[/math] value of 400 would be a "medium" workout, while 600 might take more than 2 days to recover from.
For [math]N=1[/math] we can solve [math]H\left(r\!e\!p\!s,i\!n\!t\right)[/math] for either [math]r\!e\!p\!s[/math] or [math]i\!n\!t[/math]
[equation]
\begin{align}
r\!e\!p\!s\left(H,i\!n\!t\right) &= H \cdot \left(\dfrac{100-i\!n\!t}{100}\right)^2
&
i\!n\!t\left(H,r\!e\!p\!s\right) &= 100 \cdot \left(1 - \sqrt{\dfrac{r\!e\!p\!s}{H}}\right)
\end{align}
[/equation]
which can be helpful when laying out a program. Let's say you want to know how many total reps you'd have to do at an intensity of 80% to reach an HNFM of 600
[equation]
r\!e\!p\!s\left(600,80\%\right) = 600 \cdot \left(\frac{100-80}{100}\right)^2 = 24
[/equation]
source
[equation]
W\left(m\right)={\frac {500}{a+bm+cm^{2}+dm^{3}+em^{4}+fm^{5}}}
[/equation]
where [math]m[/math] is the bodyweight in kg and [math]a[/math] through [math]f[/math] are given in the table below.
If [math]T=S+B+D[/math] is the the total of a lifter with [math]S,B,D[/math] being their top weights of squat, bench and deadlift respectively, then their wilks score is given as
[equation]
T_{\mathrm{Wilks}} = W \cdot T
[/equation]
men | women | |
[math]a[/math] | -216.0475144 | 594.31747775582 |
[math]b[/math] | 16.2606339 | -27.23842536447 |
[math]c[/math] | -0.002388645 | 0.82112226871 |
[math]d[/math] | -0.00113732 | -0.00930733913 |
[math]e[/math] | 7.01863E-06 | 4.731582E-05 |
[math]f[/math] | -1.291E-08 | -9.054E-08 |
[1] Robert Wilks, CEO of Powerlifting Australia