MIke advocates 6-10 reps for upper body and 8-15 reps for low body, ok..
but he never talk about fiber test?
Determine your 1 repetition maximum on any exercise.
Rest 5 minutes
Take 80% of this 1 repetition maximum and perform as many repetitions as possible in proper form. Do not cheat.
Make a written note of this number of repetitions
Multiply the number of repetitions by .15.
Round off the resulting figure to the nearest whole number.
Add this whole number to your 80% repetitions. This becomes the high end of your repetitions guidelines.
Subtract the same number from your 80% repetitions. This becomes the low end of your repetition guideline.
The number of repetitions that most trainees perform with 80% of their 1RM on the leg extension correlates well with their performances on other lower-body exercises. The standing biceps curl with a barbell also correlates well with other upper-body movements. Thus, by testing yourself on only the leg extension and biceps curl, you have established the repetition guidelines to apply on most other exercises.
Many trainees require higher repetitions for their lower bodies than their upper bodies. Some trainees are just the opposite. Others show no differences. The only way to find out is to test yourself according to the described instructions.
Whatever your repetition guidelines turn out to be, it is important to understand that you should not stop an exercise simply because you′ve completed a certain number. Always perform as many repetitions as possible – and then attempt one more. Make sure each set is your best effort.
For example, say your 1 rep max is 100 lbs in the barbell curl. 80% of that is 80lbs. Suppose you can perform 6 reps (2 secs up, 4 secs down) at this weight to failure. 6 x .15 = 0.9 which we round off to 1.
Thus your lower rep limit would be 5 reps (6-1), and your upper limit would be 7 reps (6+1). So you would perform between 5-7 reps in this exercise. Once you can perform more than 7 reps you would increase the weight.
As stated prior, performing a 1 repetition max (1RM) is a dangerous procedure. Thus caution should be taken if you wish to try this methodology due the risks inherent in performing a 1RM.
It should be noted that Dr. Ken Leistner and others has espoused the use of high repetition ranges for exercises that involve a significant amount of muscle mass, such as the deadlift and the squat.
In fact, his trainees have performed up to and above 20 reps in the squat. Leistner has obtained great results using this approach. Stuart McRobert, Randall Stroessen etc. have also recommended using high repetitions for this exercise. Stroessen has written a book on this technique that you can find in the book catalogue within IronMan magazine.
So, the logical conclusion is for YOU to decide upon what best suits your particular needs.
The key is you are trying to stimulate muscular growth. You never need to perform singles unless you are a powerlifter.