In issue T44 of TRAIN magazine, we asked our experts the question
What builds the most muscle? Body part splits or full body workouts?
Here’s what they had to say:
Shaun de Longeaux
Body part isolating is superior because it allows you to do more volume for the target body part and muscles grow when you rest. Training in this way allows more rest so that you can fully recover and grow from your session.
Jake Morgan 
According to famous exercise scientist Zatsiorsky, a muscle must be fatigued in order to be trained and grow. Utilizing a body part training split allows for this.
Shaun Stafford
If your routine is well structured then training one or two body parts per workout would be my preferred choice for hypertrophy (muscle building).
Michael Hildebrandt
Full body training is the best option for beginners and body part isolation training after two or three years of consistent training.
Chad Hollmer
I think that is totally dependent on a few variables. How much food are you taking in? Also, are you getting enough rest? Let’s not forget, you need a caloric surplus and rest to grow. I like to incorporate power and hypertrophy sessions throughout the week and try to get two days of rest in that mix.
Jerome Ferguson
Isolating. When you isolate the muscle, you tear it down, pump blood into it and allow it to heal for growth. That’s why you workout one body part each day.
Our Expert – Altug Kop WBFF Pro Fitness Model
I’m going to go against almost all of the experts above. Don’t get me wrong, the “bro-split” or isolating of body parts is still a viable option if you can train 6 days a week and hit each muscle group twice in that week (Like Arnold used to do), but that last part – frequency, is an important factor here.
In a recent meta-analysis, Brad Schoenfeld looked at all of the scientific studies that put training body parts 1x per week vs 2-3 x per week against each other and training each body part 2+ times per week came out on top, unanimously. Here’s an image from the meta-analysis:
As you can see almost all of the studies favoured the higher frequency protocol for optimal muscle growth.
That doesn’t mean that you can’t or shouldn’t isolate muscle groups, though. The right split for you depends on a few factors. The main thing you need to ask yourself is, “How many times can I train?”
If the answer to that question is 3 x per week :
Isolating your body parts would be the worst way to train in this case. You wouldn’t be able to train your body parts even once per week if you split them all up, let alone twice in the week.
Your ideal method of training : Full body workouts or Upper/Lower body split
If the answer to the question is 4-5 x per week :
You could potentially do a body part split here but you’re only hitting each muscle group once, which is inferior for muscle growth.
Your ideal method of training : Upper/Lower body split or a Push/Pull/Legs routine
If the answer to the question is 6-7 x per week :
You could effectively utilise a body part split here if you’re smart. Training one muscle group per session won’t work well, even in this case. Your best bet is to pair muscle groups i.e back/biceps, chest/triceps, legs/delts or whatever pairing you enjoy and allows recovery.
Your ideal method of training : The body part “bro-split” (muscle groups paired)
Final note :
Remember, although frequency is important as seen in the scientific literature, it still falls way short in importance when it comes up against overall training volume (load x sets x reps).
If you want optimal muscle growth, though, and to answer the original question that was posed : The answer is, it depends. Though in almost every scenario, isolation is inferior for muscle growth.
