# One-repetition maximum (O'Conner et al. formula)

## Description

One-repetition maximum (one rep maximum or 1RM) in weight training is the maximum amount of weight that a person can possibly lift for one repetition. It may also be considered as the maximum amount of force that can be generated in one maximal contraction. One repetition maximum can be used for determining an individual’s maximum strength and is the method for determining the winner in events such as powerlifting and weightlifting competitions. One repetition maximum can also be used as an upper limit, in order to determine the desired “load” for an exercise (as a percentage of the 1RM).

Determining the 1 rep max can be done directly through trial and error and simply requires the exerciser to complete one full repetition with the maximum weight. There are several common formulas used to estimate 1RM using the submaximal method, the Epley and the Brzycki being the most common.

Related formulas## Variables

1RM | One-repetition maximum (kg) |

w | amount of weight used (kg) |

r | number of repetitions performed (dimensionless) |