Mayhew et al developed an exponential equation for predicting the one repetition maximum weight for bench pressing. The equation is valid using a lighter weight and a greater number of repetitions to failure. The authors are from the Northeast Missouri State University.



(1) The person warms up thoroughly with light weights, calisthenics and stretching exercises.

(2) A weight is selected that is expected to result in failure with 8 to 20 repetitions.

(3) The reps are performed in a slow, continuous manner with no more than 2 seconds rest between lifts.

(4) If the person reps to failure in the 8 to 20 range (usually 10 to 15), then calculate the predicted 1 repetition maximum.

(5) If the person does not rep to failure within the 8 to 20 repetition range, let the person recover then try with a lighter or heavier weight as needed.


percent of 1 repetition maximum (as a number from 0 to 100) =

= 52.2 + (41.9 * EXP((-1) * 0.055 * (number of repetitions with that weight)))



• Mayhew et al (1993) the number 53.3 is used rather than 52.2.

• The best results are achieved with 8 to 15 repetitions. The use of a higher number (up to 20) of repetitions does not diminish the accuracy of the equation (some of the other equations using for estimating 1-RM are less accurate if the number of repetitions is greater than 10).


predicted 1 repetition maximum =

= (weight used for repetition) * 100 / (percent of 1 RM)



• Strict adherence to the protocol is required to achieve consistent results.


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