In certain exercises, many different muscles are stimulated in one lift. However, some of those muscles used reach temporary muscular failure before others. For example, when you perform the bench press exercise, you are using your pectorals, as well as your triceps and front deltoids. Since your triceps and front deltoids are smaller muscles, they will likely reach muscular failure before your pectorals. To compensate for this, you can perform dumbbell flies first, which will isolate and exhaust the pectorals. Afterwards, when you perform the bench press exercise, the pectorals, which are already tired, will go to a fatigue at the same time as the other muscles. The pre-exhaust principle is based on the concept of attacking a muscle area. First, you must exhaust it with an isolation exercise, and then immediately perform a combination movement that utilizes this target muscle. As a result, the muscle which is isolated is forced to work. It has to perform at its maximum limit because it is already pre-exhausted from the previous exercise.
Tips: 1.) It is extremely important when performing this routine to ensure that there is no rest interval between the isolation movement and the combination movement. As an example, even a very minimal rest interval, for example, only 15-20 seconds, will bring about an 80 percent rate of recovery. That is a very big number for a shock routine that relies on what is essentially a 0 rest interval. 2.) For beginners, two sets is usually plenty intense, and three sets for intermediate and advanced lifters.
Example of what I like to use it for: Most times you hear about it is used
as stated above, flyes before bench, but another way I like it is to use machine
and free weights for a biset or superset. For back workouts I like to use the
seated row machine with medium weight around 10 reps then immediately go to
t-bar rows with heavy weight for 5-6 reps. Also, I like to do pull-ups with
10-15 reps then go to pulldowns with 6-8 heavy reps.
More examples of a Pre-Exhaust Routine
Pre/ Target Muscle Group Exercise
Shoulders Lateral Dumbbell Raise/ Military Press
Chest Flat Bench Flye/ Bench Press
Quads Leg Extension/ Squat
Back Bent-Arm Pullover or machine rows/ T-Bar Row
Abs Crunch/ Hanging Leg Raises
Calves Standing Calf Raise/ Seated Calf Raise or single leg then double leg
Biceps Preacher Bench Curl or cable curls/ Standing Barbell Curl
Triceps Pressdown/ Narrow Grip Bench Press
Forearms Reverse Wrist Curl/ Reverse Curl