How to work out your one rep max
Our latest blog gives advice to personal trainers on how to work out a client’s one rep max.
When personal trainers and fitness instructors are writing gym programmes, a major distinction between different clients’ goals and abilities is the intensity that they are able to work at. Commonly, this is referred to as endurance, hypertrophy or strength, but this is very general terminology. If a personal trainer wants to be more specific, they would talk about percentages of a client’s one rep max.
As a general guideline:
Endurance - would range between around 12 to 20 reps, which equates to around 65% or lower of an individual’s one rep max.
Hypertrophy - ranges from six to 12 reps, which equates to around 65%-85% of a one rep max.
Strength - ranges from one to five reps, which equates to 85% to 100% of a one rep max.
The dangers for a beginner carrying out a one rep max
However, these percentages can be difficult for a client to follow if they don’t already know what their one rep max is. If someone is a beginner, a personal trainer would not necessarily want them to perform their one rep max as they could easily injure themselves.
It follows that if someone doesn’t know their one rep max, they can’t embark on endurance training at, say, 65% of their one rep max. Even with someone who has been training regularly, they may be able to carry out a five rep max, but they may not be ready to carry out their one rep max.
Based on a one rep max being 100%, a two rep max would be 95%, and then for each two reps, the percentage would go down by 5%, so:
1 rep max = 100%
2 rep max = 95%
3 rep max = 93%
4 rep max = 90%
5 rep max = 87%
6 rep max = 85%
A personal trainer can calculate the correct weight a client should lift using the attached chart, but they can also calculate it manually. If an individual is lifting 85kg for 6 reps, then based on the figures above, that would equate to working at 85% and it would mean that their one rep max would be 100kg.
A simple equation to illustrate this would be:
85kg x 0.85 (85% for 5 reps) = 1 x 100 (100% for 1RM) = 100kg
If someone is lifting 75kg for eight reps, eight reps equates to 80% of their one rep max, so 100% of their one rep max would be 93kg:
75kg x 0.8 (80% for 8 reps) = 0.93 x 100 (100% for 1RM) = 93kg
Once a fitness instructor has calculated a client’s predicted one rep max, they can easily alter the percentage of the one rep max at which the client is working. So for the individual who has a one rep max of 93kg, if a personal trainer wanted to work them at 75% of their one rep max, the calculation would be:
93kg x 0.75 = 69.75kg
So, following the previous chart, the client with a one rep max of 93kg should be able to carry out 10 reps (ie 75% of their one rep max) at 69.75kg.