A study of 300,000 gym sets shows the old formulas for predicting max strength are completely wrong.
March 19, 2026
Original Paper
A Weight-Dependent 1RM Prediction Equation Optimized on 303,494 Near-Failure Sets Across 388 Exercises
arXiv · 2603.17495
The Takeaway
Most athletes use a simple multiplier to estimate their 'One Rep Max,' but this massive analysis of 388 different exercises shows that muscles don't fatigue in a straight line. The researchers discovered a logarithmic relationship that changes based on how heavy the weight is, meaning millions of workout plans are currently based on incorrect math.
From the abstract
Classical equations for predicting one-repetition maximum (1RM) from submaximal performance were derived from small samples performing a single exercise, yet are routinely applied to hundreds of exercises. All use a fixed conversion factor relating repetitions to estimated 1RM, regardless of exercise or load. We used large-scale observational data from a consumer fitness app (303,494 near-failure sets from 14,966 users across 388 exercises spanning 16 muscle groups) to derive and evaluate a gene