Experimenting with full-body workouts and bro splits

Muscle Hypertropy: An increase in size of skeletal muscle. Better known as gainz.

tl;dr

There’s no clear answer about whether bodypart splits or full-body workouts lead to more muscle growth. 5 months of my own personal data suggests that bro splits maximize workout intensity and duration, and full-body workouts maximize workout frequency. For me personally, I saw muscle growth under both workout programs. My recommendation is to introduce novelty into your programming (if you’re doing splits now, try full-body) and track your results with a keen eye on how frequent, intense, and long your workouts are.

Background

If you want to build muscle, there are two schools of thought in workout programming:

  • Bro Split. You hit different muscle groups on different days. Chest + Triceps one day, Back + Biceps another day.
  • Full-body routine. You work out every muscle group in one workout, 3 times per week.

So which is better? You would think science would have solved this puzzle already, right? Not so. I only found one credible study that compared bro splits to full-body workouts.

Brad Schoenfeld, the self-proclaimed “Hypertrophy Specialist”, tried to answer this question by running a split test with 19 well-trained men. His findings: There was a significant (1.1mm) gain in forearm flexor muscle thickness in the full-body group, compared to the bro split group.

Problem solved? Not quite. Here’s why, straight from Brad’s analysis of his own study.

The study controlled for volume.

It’s important to remember that the study equated volume between conditions. This was done to isolate the effects of frequency on muscular adaptations — an essential strategy for determining causality. However, a primary benefit of a split routine is the ability to increase per-workout volume while affording ample recovery between sessions. Since there is a clear dose-response relationship between volume and hypertrophy, total weekly volume needs to be factored into the equation. Certainly it’s possible that a split routine with a higher weekly volume would have performed as well or even better than the total body routine.

Novelty factor

The vast majority of subjects in the study reported using a split routine as the basis of their usual workout programs, with muscles worked just once per week. This raises the possibility that the novelty factor of the total body routine influenced results. There is in fact some research showing that muscular adaptations are enhanced when program variables are altered outside of traditional norms. It’s therefore conceivable that participants in the total body group benefited from the unaccustomed stimulus of training more frequently.

The experiment

Since the verdict is still out, I set out to try three different workout programs to see how my body responded to each.

The 3 Workout Programs

Bro Split, 4 days per week.

  • Chest, Shoulders, Triceps 1x per week
  • Back, Biceps 1x per week
  • Legs 1x per week
  • Abs 1x per week

Full-body, 3 days per week.

  • Chest, Shoulders, Triceps, Biceps, Back Legs, Abs 3x per week

Upper/Lower split, 4 days per week.

  • Chest, Shoulders, Triceps, Biceps, Upper Back 2x per week
  • Legs, Abs, Lower Back 2x per week

4 Key Metrics

I measured four variables over the course of the workouts:

  • Workout Intensity: Number of reps per week
  • Workout Duration: Total time of weekly workouts
  • Workout Frequency: Workouts per week, per body part
  • Muscle Mass: Muscle Mass % x Weight

Why did I pick these metrics? Intensity, duration, and frequency are the three main levers one can use to progress their workouts. Lifting more weight (intensity), for longer periods (duration), more often (frequency) is the recipe for building muscle mass.

What were the results

Bro splits maximized intensity and duration at the expense of frequency.
Full-body maximized frequency at the expense of duration and intensity.
Upper/lower fell between the two others on frequency, duration, and intensity.
Full-body maximizes frequency, bro split maximizes intensity and duration.

Bro split

  • Intensity: More intense than full-body, about even with upper/lower split. 1,075 reps per week.
  • Duration: Longer than both full-body and upper/lower. 208 minutes per week.
  • Frequency: Lower than both full-body and upper/lower. 0.96 workouts per body part, per week

Full-body

  • Intensity: Less intense than both bro split and upper/lower split. 950 reps per week
  • Duration: Shorter than both bro split and upper/lower split. 164 minutes per week.
  • Frequency: Higher than both bro split and upper/lower split. 2.81 workouts per body part, per week.

Upper/Lower Split

  • Intensity: Higher than full body, about even with bro split. 1,065 reps per week.
  • Duration: Higher than full body, lower than bro split. 197 minutes per week.
  • Frequency: Lower than full body, higher than bro split. 1.60 workouts per week, per body part.

What about Muscle Mass? Muscle Mass was hard to measure over the past 5 months because I did a mini-cut in March during the full-body workouts. I think the drop in muscle mass in March was because of calorie restriction, not workout programming. But, I hope to test out a full-body routine again when my calorie consumption is more consistent. Overall, it looks like all three programming structures allowed me to put on muscle mass.

So which one did I pick?

I love full-body workouts because they allow me to hit muscle groups 3 times per week. However, I find it difficult to know if I’m pushing it too hard or not hard enough. With a full-body routine, you have to reduce intensity because you’re going to be hitting that muscle group again after only one day off.

I love bro splits because it’s easier and takes less planning. On chest day, you just lift as hard as you can and then take 5–6 days off. Unlike full-body, there’s no worry about whether or not you’ll be ready for another workout in a couple of days.

I settled on something in between: Upper/lower splits. Upper/lower splits allowed me to hit each muscle group 2 times per week, and they gave me 2–3 days of recovery. For now, I’m sticking with upper/lower, but I plan to rotate through full body and bro splits to capitalize on the novelty factor of training.

If you’re interested in the source data for this post, you can find it here.