Q: I just read a report saying that pre-exhaust doesn’t actually work. So why does M&F still recommend it?
Pre-exhaust is a technique that flips the typical order of exercises so you perform single-joint or isolation moves first, before multijoint or compound exercises. The point is to fatigue the muscle group of interest with an isolation move so that when you perform the multijoint exercise, which involves other muscle groups, the target muscle is already exhausted. This ensures that the target muscle receives ample overload so your other muscles don’t fatigue first and limit the amount of work you can perform. This method of training was shown in a 1996 study to build more muscle than standard training, in which you do multijoint exercises first.
The research you’re referring to is a 2007 study out of Brazil. Scientists had weight-trained men perform one set each of the machine chest press and pec-deck flye in alternating order while they measured muscle activity of the pecs, front delts and triceps. In one workout, the subjects used the standard method of doing the chest press first, followed by the pec-deck flye. In the other they used the pre-exhaust method of doing the pec-deck flye first, followed by the chest press.
The researchers reported in the Journal of Strength and Conditioning Research that when subjects used the pre-exhaust system, their triceps muscle activity was higher and their pectoral muscle activity was lower during the chest press. Therefore, the scientists concluded (erroneously, we might add) that pre-exhaust isn’t effective.
This finding is similar to results that Swedish researchers reported in a 2003 study. They had trained males perform one set of the multijoint leg press with or without pre-exhausting on the single-joint leg extension first, and found that the activity of subjects’ quadriceps muscles was significantly less during the leg press when they used pre-exhaust. The scientists concluded (again erroneously) that “our ﬁndings do not support the popular belief of weight trainers that performing pre-exhaustion exercise is more effective in order to enhance muscle activity compared to regular weight training.
Conversely, pre-exhaustion exercise may have disadvantageous effects on performance, such as decreased muscle activity and reduction in strength, during multijoint exercise.
Unfortunately, these Brazilian and Swedish researchers were misinformed regarding the reason bodybuilders use pre-exhaust. It wasn’t designed to increase activity in the muscle of interest but to increase the fatigue of the muscle of interest, hence the name.
Therefore, these two studies showing that the target muscles (pecs in the Brazilian study and quads in the Swedish study) experienced a decrease in muscle activity during pre-exhaust proves that it works to exhaust the muscle. When a muscle becomes fatigued, it decreases muscle activity.
Be careful what you read; even scientists get it wrong. Of course, that’s not surprising, since not many scientists except for us at M&F actually train as bodybuilders.
Bodybuilders who have utilized this technique can tell you the muscle gains they’ve experienced using pre-exhaustion. Despite the fact that these study results showed pre-exhaust not to be effective, it does work. So keep using pre-exhaust in your training.