Estimating a One-Rep Max Without Testing One
You can predict your one-rep max from a set taken close to failure, and there are dozens of published formulas for it. The two most established disagree in a useful way: Epley trends high as reps climb, Brzycki trends low, and the gap between them widens past about ten reps. Kriterion averages the two, which cancels much of each one's individual bias. The important caveat is that all of these equations were validated in low rep ranges, roughly one to ten. A set of twenty tells you a great deal about your endurance and very little about your maximum, and any formula claiming otherwise is extrapolating well past its evidence.
Treat a predicted max from a high-rep set as a rough direction rather than a number.
Kriterion estimates your max from the sets you already logged, and shows the working rather than just the answer.
References
- Brzycki M. Strength testing — predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 1993.
- Epley B. Poundage chart. Boyd Epley Workout. University of Nebraska, 1985.
- LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research, 1997.
Kriterion is the app this reasoning is built into
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