Below is the core of the method that we use to establish the right start load in resistance training programs (From Maximal Strength - How To Manifest Untapped Potential For Strength Using The Flexible Periodization Method)
1. Explain the concept of rate of perceived exertion (RPE) to the athlete or client.
2. Three or more sets with gradually increasing loads are performed to find the right start load
First set = estimate load so target rep results in RPE 1-2 out of 5 - it is a judgment call, that gets easier with experience. There should be no visible strain in the clients face during this set.
If the client has never tried this particular exercise variation before, it is a complete “guestimate” which load to use. If the client has trained with the particular exercise variation before, for example three months ago, you should use his past performance to guestimate the correct load. This is just one of many situations where training logs come in handy.
(Use a relatively short rest period between the first and the second set)
Second set = estimate the load so target rep results in RPE 2-3 out of 5 – to achieve the increase in rate of perceived exertion the load should most often be increased with 5-25 pounds.
! If the RPE is on the low side increase the weight more before the next set. If the RPE is on the high side, increase the RPE less before the next set.
(After the second and after subsequent sets you should use the standard rest periods for the repetition bracket in the program).
Third set = estimate the load, so the target rep results in RPE 4 out of 5 – to achieve the increase in rate of perceived exertion the load should most often be increased with 5-25 pounds. There should be visible strain and muscular contraction in the clients face and body, but the technique should off course still be perfect. In order words, the set should be a solid effort, yet nowhere near failure)
This sequence can be extended 1-2 sets, in some cases even more if needed.
The load that results in a RPE of 4 out of 5 for the target repetitions is the start load for the program