This question is related to the hypertrophy cornerstone course but can be very valuable for all experienced lifters on this forum when programming their training.
As stated in the course, you can use the 80% rep test on an exercise to determine the muscle fiber dominance of your trainee/client (based upon how many reps are performed with 80%).
But is this test not influenced by exercise selection? For example a leg extension, where you are only using quads, can have a very different result than a back squat, in which you are using more (and potentially weak) muscles?
Or if you select an exercise where the lifter is either in a mechanical advantage or disadvantage, will that not also have an impact on the outcome?
Lastly if you use an isolation exercise for the test, doesn’t the result only give information about muscle fiber dominance of that specific muscle group?
How would you approach this Coach?