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RM Formulas

Posted: Fri Oct 26, 2012 4:52 pm
by Oscar_Actuary
In general, wouldn't it make sense to have different formulae for different lifts?

For example, the OH Press vs Bench. I figure given an accurate 1 RM, I can kick out more reps at 80% of that on Bench than I can for OH Press.

Ex
1 RM bench; 200, 80% 160
1 RM press: 120, 80% 96

And take this logic to squat. I'd say its even more so. Meaning even more reps than Bench. IDK, to me the large muscles can sustain the lifting longer.

Am I all wrong and the formulas are good enough to us across all lifts?

Re: RM Formulas

Posted: Fri Oct 26, 2012 5:34 pm
by pdellorto
No, it would likely be different across all lifts, although it might not vary that much. It would vary more across lifters than across lifts done by that lifter, if you follow.


It also varies, in my experience, by sex. I've had women knock off sets of 12-15 reps with a weight, then you add 5 pounds to the bar and they get 0 reps. They seem to get higher reps at a much higher percent of the 1RM than men, for any lift. I'm not sure why that is.

Re: RM Formulas

Posted: Sat Oct 27, 2012 9:44 am
by Jungledoc
I think that there have been attempts to develop formulas for specific lifts. I once came across a website that had (as I recall), 24 different formulas. You could enter one set of variables and get the results that each of them generated. My problem was that the text was all in French, which, despite Madame Lytle's best efforts, I can't read. Of course now I could use something like Google Translate, so maybe I should try to find it again.

Re: RM Formulas

Posted: Sat Oct 27, 2012 10:14 am
by Jungledoc

Re: RM Formulas

Posted: Sat Oct 27, 2012 1:52 pm
by Wouter
I just use the one from this site: http://exrx.net/Calculators/OneRepMax.html

Re: RM Formulas

Posted: Sat Oct 27, 2012 4:44 pm
by Jungledoc
Wouter wrote:I just use the one from this site: http://exrx.net/Calculators/OneRepMax.html
Why do you prefer it?

Re: RM Formulas

Posted: Sat Oct 27, 2012 4:50 pm
by KenDowns
Oscar_Actuary wrote:In general, wouldn't it make sense to have different formulae for different lifts?

For example, the OH Press vs Bench. I figure given an accurate 1 RM, I can kick out more reps at 80% of that on Bench than I can for OH Press.
The formula in Wendler's book (which is not original to him) can be generalized to:

1RM = Weight * (1 + Reps/k)

Where the value of 33 for k is pretty common, and is meant to hit the middle of the bell curve for general fast/slow twitch mix. For those with generally more slow twitch, who are better at endurance, you want to predict a lower number, so k goes up, making each rep worth less in predicting the 1RM.

This formula works pretty well for me on bench and squat, suggesting I'm average. It falls off for dead and press, in opposite directions. Not surprisingly, it overpredicts for me for Press, which involves smaller muscles than bench and squat. For dead it undepredicts, which also makes sense because there are more fast twitch muscles working there.

That's all I know.