Other/Mixed Regressing a formula

[Glen]

I like formulas for barbell training, it gives me predictive options to see if things are on track.

Currently trying to work out how to alter the wendler (Eply) formula so that if I have a given work weight, how many repetitions needed with it to achieve a desired predicted 1RM.

Anyone know how to do this?

For instance the Eply formula is

Max = weight (1+repsx0.3)

If max is A, weight is B, reps are C what formula would I use to predict C from knowing A and B?

Been trying for a while and it doesn't seem to work for me altering the formula.

Damn those people who said when will you use algebra in real life!!! Do they even lift!

 

[ali]

@Glen,

C= 30 (A/B) - 30.

So A max 120, B weight 80

30 (1.5) - 30

15 reps!

 

[Glen]

Thank you!

 

[ali]

No problem... Coffee and algebra'

 

[ali]

Oh @Glen.... Meant to say: the reason why you may have had a problem it was C over 30, C/30....rather than C x 0.3.....which should be 0.0333333.

Could also be so: C = A-B/0.033333B

Use 0.03, you get a rounding error.

Or, C=30A-30B/B in a different form....earlier one is easier.

 

[Glen]

Oh @Glen.... Meant to say: the reason why you may have had a problem it was C over 30, C/30....rather than C x 0.3.....which should be 0.0333333.

Could also be so: C = A-B/0.033333B

Use 0.03, you get a rounding error.

Or, C=30A-30B/B in a different form....earlier one is easier.

Thank you.

First one is much easier, added to spreadsheet and all working well. Thanks

 

[ali]

Good stuff!
As much as it is a formula....is it an accurate one?

 

[Glen]

Good stuff!
As much as it is a formula....is it an accurate one?

That's what I hope to find out, aim is to do a nine week cycle of 5/3/1

Use the formula to try and estimate my reps with a given weight so I have a minimum target, then track estimated max weekly up to an actual test on the tenth week.

 

[ali]

I've limited experience at 1Rm - ing. And my estimates at %RM could be better, I think. Might use that for guidance, cheers.

 

[ClaudeR]

@ali to the rescue with the maths stuff! Great job!

@Glen, one potential issue with this is the accuracy of the formula diminishes the further the reps go away from “1”... meaning if you’d stick to the original formula and 15 reps as per Ali’s example, the confidence level of the resulting 1RM would be low. Generally it is said that anything over 8or so reps is considered unreliable and you’d add weight and test again

so what that means for you is inversely true... if your formula says you need 15 reps for a new RM, take it with a grain of salt. It works very well as a target for a 5/3/1 AMRAP set to gauge progress (as it can be graphed nicely, and I have actually done the same in the past), but is not to be used for any proper decision making

 

[Glen]

Hello @ClaudeR yes I'm aware of that, for me it's just a rough figure to give targets as the cycles progress.

 

[ClaudeR]

I did just that, and it worked well!