Quote (cloudkicker @ Jan 23 2018 10:54pm)
a % of a 1RM is a tangible, discrete reflection of proportion of maximal effort. your muscle changes very little from day to day, just like you wont lose a noticeable amount of muscle in a few days, you wont gain anything in that period of time either. muscle mass very strictly correlates to peak force. so long as you're adequately hydrated and not sleep deprived, the only thing really influencing day to day variations in strength substantially will be motivation. motivation is the variability that RPE aims to correct for, however neither variable is measurable. you cannot build a reliable, predictable training regime off of a variable that you cannot measure. the actual value that RPE is meant to proxy is essentially the amount of anaerobic energy you have at your disposal for a given set of work. if thats what you want to build a training routine around, why not actually measure anaerobic energy store and use a meaningful metric to calibrate your workout
1rm does change form day to day especially when cycling volume.... It goes up and down from volume, stress, nutrition, rest etc. You can make it reliable by practicing it just like any other variable in your training. You've the right to not like it does work for thousands so there's that. ¯\_('-')_/¯