Help with Single's Club

[RSM8]

I tried to do chin-ups 3X18 with 60% of my one rep max and couldn't get anywhere close to 18 reps. My last set I did just bodyweight and even that was hard (of course I was fatigued from starting out with a 35Ibs plate then 25).
Did anyone else have this problem?

Last week I finished HH and was doing 4X3 with 70 Ibs hanging from my belt.

I seem to have the same problem with BB curls also.

Obviously I'll drop weight but I was wondering the reasoning behind this. Any guesses? Thanks

[Aoife]

60% of your 1RM of bodyweight + extra weight? Or just 60% of the extra weight, which wouldn't be 60% of your 1RM.

And the formulas (if that's what you're going by as to how much you should be able to do) aren't always right, esp if going from a 1rm to an 18rm.

[RSM8]

WOW..Ok..I feel stupid. I always figured it from how much weight I was adding to my bodyweight. For example I can probably do around 75Ibs added to my bodyweight for a 1RM chin-up.

[Aoife]

Nah. Not stupid. But if you weren't accounting for the extra hundred and whatever, that'd prolly explain it.