Intensities are percentages of your 1 rep max.
How to interpret this chart:
The “Intensity” is the percentage of the 1 rep maximum that you’re using for a given lift. Keep in mind that your 5RM is about 90% of your 1RM and your 8RM is about 80% of your 1RM.
The “Reps/set” column is telling you the optimal rep range for every set you do at a given intensity. So if you’re lifting at 80% of your 1RM, you should use between 2 and 4 reps for every set.
The “Optimal total” column lists the optimal number of total reps in a single workout at a given intensity. Continuing with our example of a lifter using 80% of his 1RM, the optimal number of reps the lifter could perform for this exercise during one workout would be 15.
The “Total range” column lists the minimum and maximum number of total reps a lifter should perform at a given intensity. So our lifter using 80% should perform at least 10 reps and at most 20 reps. Any less would be too easy and any more would be too taxing.
Using Prilepin’s table to design set/rep schemes:
This information gives a lifter a lot of possibilities to design set and rep schemes for a workout. Let’s say we have a lifter squatting at 80% of his 1RM. These are the best options for set/rep schemes according to Prilepin’s table:
There are many more possibilities, but they stray away from the optimal total number of reps, which is 15.
More advanced discussion:
Prilepin’s table fails a bit because it doesn’t distinguish between intensities within a certain range. It is obviously tougher to lift at 85% of your 1RM than it is to lift at 80%, but Prilepin’s table makes no distinction between these weights.
The table also doesn’t help when a lifter wants to use different intensities in one workout. If a lifter wants to do a set at 75% and another 3 sets at 85%, the table doesn’t offer a solution to the ideal number of sets/reps.
This is where we make some adjustments:
Adjusted number of lifts gives you an idea of the difficulty of a single set. So, using the previous example of a person squatting 5×3 @ 80% of their 1RM:
The total number of lifts is 15. The intensity is 80%. So the adjusted number of lifts is:
15 / (100-80) = 0.75
If the lifter were to do 1 set of 5 at 75% and 3 sets of 4 at 80%, the adjusted number of lifts would be:
1×5 / (100-75) + 3×4 / (100-80) = 5/25 + 12/20 = 0.8
Using this scheme, the 2nd workout is slightly more difficult.
Guidelines for adjusted number of lifts:
For each week of training, it’s best to keep the adjusted number of lifts between 2 and 4. Doing less than 2 may work for those who are deloading. Doing more than 4 is extremely difficult. Adjusted numbers of lifts between 3 and 4 are taxing and might not be sustainable over months.
For each individual workout, try to keep the adjusted number of lifts between 0.4 and 2 for any single exercise.