How do you work out your 1 rep max...

If you was to do a 5 x 5 routine then how much more weight could you do for a 1 rep max lift?

Any rough examples?

I'd probably do (the weight you used for 5x5 x 0.0.333 x 7) + the weight you used for 5x5

Where did you get the idea for working it out this way and I tried it but it's just error.

Yup- weight lifted x 0.033 x reps + weight lifted= 1RM. It's pretty close as well.

It's in the 531 book.

Well its not error.

What is the weight you used for 5x5?
Multiply this by 0.0333, then by 7.
then ADD that to the weight you used for 5x5

so, e.g you used 50kg

50 x 0.0333 x 7 = boobies

boobies + 50 = 1rm

Thanks that seems to work better, smalls put 2 decimal places that through me a bit lol

I have sorted it now mate, nice one and just that the first time you put 0.0.33

or you could use this.
http://www.exrx.net/Calculators/OneRepMax.html

Or you could just go to the gym, pick a lift and work up to a 1RM.

I have used this before but from doing 1 set it is okay but doing the same weight for 5 continuous sets then the 1 rep max would then be higher, wouldn't it?

yeah, I suppose you would just have to take a guess. Or work out your 5 rep max for 1 set first.

That is out of the question at the present moment with my back and just want to work on 5x5 and 8x5 for the next few months so at least now I can roughly keep an eye on what my 1 rep max should be about.

If your back is giving you hassle your 1RM should be the last thing you keep an eye on.

My back is getting better but don't want to be loading close to maximum weights and going backwards again and doing the routine I have planned will be adding such a little extra pressure each week so at least i can continue some sort of progress forward on my strentgh, without 1 repping all the time.

A sensible approach to rehab, but if you're doing 5x5's you wont be anywhere near your 1RM, so no real need to worry about it IMO. Concentrate on what you're doing.