The pre-exhaustion or pre-fatigue method has been advocated by high intensity training advocates – including Arthur Jones, Mike Mentzer, Ellington Darden and others – for improving the results of training torso and thigh muscles. Many continue to implement this technique, believing it will improve their training results.
In this article I will explain why you should avoid using the pre-fatigue method.
The pre-exhaustion method rested on the belief that when doing multi-joint exercises one of the multiple muscles involved is a "weak link" that fails before the largest target muscle. For example, it was claimed that when doing a chin up the biceps are the weak link, and when doing push-ups the triceps are the weak link.
The pre-exhaust technique was developed to get around this alleged weak link. The method involves doing a single- joint exercise for the torso muscle to "pre-exhaust" it then as quickly as possible do a multi-joint exercise for that muscle. It was claimed that then the fresh but smaller muscle ( biceps or triceps) would help the larger torso muscles (upper back or pectorals) do more work.
A simple biomechanical analysis would have revealed that this was misguided. In order for one muscle to help another the two must cross the same joint and have the same function on the levers at that joint. This does not apply to any of the pre-exhaustion protocols for torso muscles.
The biceps only functions are to bend the elbows, supinate the wrists and flex the shoulder. The latissimus dorsi extends the upper arm. Thus the biceps can't assist the lats because it doesn't perform the same function as the lats i.e. extension of the upper arm. Same applies to the triceps and pectorals or deltoids.
For the thighs, the quadriceps extend the knee in squats, leg presses and leg extensions, while the gluteus and hamstrings extend the femur. Since the glutes and hamstrings don’t extend the knee, they can’t directly “help” the quadriceps extend the knee. In fact, performing leg extensions or similar quadriceps isolation exercises before squats or leg presses just means you won't be able to use as much resistance in the multi-joint movement, which probably means that the gluteus will not receive as much stimulation as if you did the multi-joint exercise first. (This might be valuable if a trainee has a compromised lower back.)
Moreover no one has ever established experimentally that the upper arm muscles fatigue before the torso muscles in multi-joint torso exercises, or that the quadricpes fatigue before the glutes (or vice versa) in squats or leg presses. It is unlikely this is the case in multi-joint torso exercises since the direction of resistance in such exercises is not in direct opposition to the function of the arm muscles.
Golas et al investigated whether performing a single joint exercise (incline dumbbell fly) for the pectoralis major (PM) before the bench press would produce higher PM activation during the bench press than without pre-exhaustion. 1 They found peak PM activation was not significantly different regardless of pre-exhaustion. However, performing a triceps isolation exercise before bench press did result in a higher activation of the triceps during bench press. This is because normally during bench press the triceps are not a weak link because the resistance is not directly opposed to triceps function; however if you pre-fatigue the triceps, they will have to work harder in the bench press.
Gentil et al performed a similar experiment using a pec dec and chest press and also reported that “performing pre-exhaustion exercise is no more effective in increasing the activation of the prefatigued muscles during the multi-joint exercise.”2
Augustsson et al tested muscle activation of the quadriceps and gluteus maximus in the leg press with and without pre-exhaustion with the leg extension.3 They reported that the quadriceps activation during the leg press exercise was significantly less when the quadriceps were pre-exhausted with the leg extension! Moreover, there was no change in activation of the gluteus maximus with pre-exhaustion.
Finally, Fisher et al put the pre-exhaust hypothesis to another empirical test.4 They found that using the pre-exhaust method did not produce any better gains in strength or mass than performing the same movements but with a normal rest period between them.
In fact, the graphic presentation of the results suggests that incorporating a normal rest period shows a trend toward superior results in comparison to the pre-exhaustion method .
In summary, the pre-exhaustion method lacks a sound biomechanical basis, and has been shown ineffective at increasing torso muscle activation or strength gains. I recommend you avoid it.