Meaning
One repetition maximum; the heaviest weight that could be lifted in an exercise for one rep.
For example, a 50 kg deadlift 1RM means you can complete only one repetition of the exercise with this weight, and increasing the weight further prevents the completion of a single rep.
Why find your 1RM?
Knowledge of your 1RM assists vastly with training as it ensures you use sufficiently heavy weights to induce targeted physical adaptations.
For example, training using larger percentages of your 1RM is necessary to produce optimal maximal strength adaptations such as increased neuromuscular efficiency. Similarly, training with low percentages of your 1RM allows for a higher number of reps, hence inducing muscular endurance adaptations such as improved efficiency of nutrient delivery.
How to find your 1RM?
There are two ways of knowing your 1RM:
- Testing: perform warm up sets up to where you think your 1RM might be and attempt it.
- Estimation: use a weight and number of repetitions (very close to or until failure) you have done with that weight in a 1RM calculator. You could also calculate manually using the Brzycki or Epley formula, the former tends to be more accurate for lower reps (10 and below).