Have you been training and found your workouts to be too easy or too hard? Are you using percentages of your 1-rep max (1RM) to guide your training, but feel like you’re missing the mark? A relative intensity calculator may be a good option for you! A relative intensity calculator gives you an idea of how hard a set and rep scheme really is at a given percentage of 1 RM. To find your relative intensity for a given exercise, you will need 3 pieces of information.
- Relative intensity of reps per set that equates to 1 rep at 100% of 1RM
- Reps performed at a given % of 1RM
- Total reps performed
The first step mentioned requires knowing what % of 1RM at a given rep scheme (set of 2, 3, 4, or 5, etc.) would equal 100% effort to complete. For example, at 90% of 1RM the most you can perform is 4 reps. So that means that if I performed a set of 4 reps for a given exercise, the highest % I can go is 90% of my 1RM. Luckily, there is a chart that shows what % of 1RM you can perform at certain reps. Here’s how it looks.
Another example is if we perform a set of 8 reps, the heaviest weight we could perform would be 80% of our 1RM. The reps you see on the left column align with the percentages on the right column that would equal to 1 rep at 100%. Now with that in mind, any good exercise programmer who uses % of 1RM to determine the intensity of an exercise would be foolish to be assigning a set of 8 reps at 80% of 1RM because you are relatively doing 100% max weight! What I’m saying is, if you’re performing 8 reps, you want to do less than 80% of your 1RM to avoid burn out and potentially miss a lift for being too heavy. At 8 reps, that 80% is now your 100%, relatively speaking. Makes sense?
The mathematical equation is this:
Relative Intensity = Actual % of 1RM/Relative Intensity of a given rep
Let’s see how a set of 6 reps at 70% of 1RM would look like.
Relative Intensity = 70% (Actual Percentage) / 85% (Relative Intensity at 6 reps, referred on the chart above)
~82% relative intensity = 70%/85%
What this means is that doing a set of 6 reps at 70% will feel like doing 1 rep at 82%. This helps you get perspective how hard that set really is, which is extremely useful information! Now that we have that figured out, we need to get a relative intensity of an entire set and rep scheme. Pull out your calculators, because we are about to do some more math. Let’s compare these set and rep schemes: 4 sets of 6 reps at 65% for all sets compared to 3 sets of 8 reps ramping up % each set at 60%, 65%, and 70%, respectively, and see how relatively hard they really are.
| 1st set and rep scheme | Actual %/Relative %= Relative Intensity | 2nd Set and Rep Scheme | Actual %/Relative %= Relative Intensity |
| 1 set of 6 reps at 65% | 65%/85%=76% | 1 set of 8 reps at 60% | 60%/80%=75% |
| 1 set of 6 reps at 65% | 65%/85%=76% | 1 set of 8 reps at 65% | 65%/80%=81% |
| 1 set of 6 reps at 65% | 65%/85%=76% | 1 set of 8 reps at 70% | 70%/80%=88% |
| 1 set of 6 reps at 65% | 65%/85%=76% | n/a | n/a |
| Total Reps = 24 reps | Average Relative Intensity: 76% | Total Reps = 24 reps | Average Relative Intensity: 81% |
Final Thoughts:
As you can see from the table above, 3 sets of 8 reps at 60-70% is relatively the harder workout compared to 4 sets of 6 at 65%. With this information you can compare any set and rep scheme at any percentage of your 1RM of your choosing and be able to do the math to ensure that your workouts are optimal and progressing at a steady rate. If you found this post helpful, share it with anyone you think could benefit from it! Good luck, and GET AFTER IT!
Charles Performance and Wellness 