If you have ever finished a tough set of leg extensions and then moved on to squats, you might have tried “Joe Weider’s Pre-Exhaustion Principle.” This technique has been popular among old-school bodybuilders. The idea is to tire out a muscle first with an isolation exercise. This way, the muscle works harder during the following compound exercise.
But does this method really help build muscle or burn fat better? Researchers noticed that there was little scientific evidence to prove it. So, they decided to study it, and their findings could change how people train.
What the Study Looked At
The study, published as a pre-print on SportRχiv, compared pre-exhaustion training (PreEx) to traditional training (TRAD). It examined their effects on muscle growth, strength, body composition, endurance, and lower-body power. The study lasted eight weeks and involved experienced lifters.
What Is Pre-Exhaustion Training?
Pre-exhaustion training starts with an isolation exercise to fatigue a muscle. Then, a compound exercise for the same muscle group follows. For example, doing leg extensions before squats. The idea is that pre-fatiguing the muscle forces it to work harder during the compound lift, possibly increasing muscle growth. The study aimed to test if this idea holds true.
How the Study Was Done
Forty-eight participants with at least one year of regular resistance training took part. They were randomly split into two groups: pre-exhaustion and traditional.
Each group trained twice a week. They did four sets of each exercise, using weights they could lift 8 to 12 times.
Both groups did the same exercises: leg extensions, Smith machine squats, seated hamstring curls, and Romanian deadlifts.
The traditional group did all sets of one exercise before moving on to the next. They rested for two minutes between sets.
The pre-exhaustion group did each isolation exercise immediately followed by the related compound exercise. They rested two minutes between these paired sets (called supersets).
Before and after the study, researchers measured muscle thickness using ultrasound, tested squat strength with one-rep max (1RM), measured jump power, checked muscular endurance via leg extension reps at 60% body weight, and analyzed body composition through bioelectrical impedance.
Participants logged their food intake. Training sessions were supervised, and data on recovery and effort were collected.
Key Findings
Muscle Growth:
Both groups increased muscle size over eight weeks. The traditional group showed slightly better growth in all measured muscle areas, but the difference was small and not very clear.
Strength:
Both groups improved their squat 1RM. The traditional group gained about 1.8 kg more, but this difference was not statistically significant.
Endurance and Power:
The groups had similar improvements.
Body Composition and Fat Loss:
The traditional group lost slightly more body fat (about 1.2%) and gained a bit more lean muscle than the pre-exhaustion group. The pre-exhaustion group’s fat levels increased slightly. Still, overall changes were modest.
What Does This Mean?
Dr. Pak Androulakis-Korakakis, one of the study’s authors, said, “Traditional training led to slightly more muscle growth, but the difference was small and uncertain. Strength, power, and endurance gains were similar. Pre-exhaustion workouts took 36% less time but felt more tiring.”
He added, “Pre-exhaustion is time-efficient and effective, but if you want to maximize muscle gains, traditional sets might be the better choice.”
This does not mean you should stop using pre-exhaustion if you enjoy it. But for pure muscle growth, straight sets might be a smarter use of your time.
Regarding fat loss, focusing on compound exercises might help burn more calories. This can create a bigger calorie deficit and make pre-exhaustion less necessary.
Still, the best way to lose fat is by managing your diet. Exercise helps, but food and drink usually have a bigger impact on your total daily energy balance.
