For lifters looking to maximize muscle growth, the endless debate over workout routines can be paralyzing. Should you do a bro split, run Push/Pull/Legs, or switch to full body training?

According to Dr. Milo Wolf, a PhD in sports science, the answer isn’t about what’s popular—it’s about what the research shows. Here’s the science-backed guide to choosing the best routine for building muscle.

The Two Pillars of an Effective Routine

Before picking a specific split, your routine must satisfy two fundamental requirements for hypertrophy (muscle growth):

1. Sufficient Recovery: You need enough rest between training the same muscle group so that your performance doesn’t decline. Training a muscle while it’s still deeply fatigued compromises the stimulus you provide.

2. Optimal Frequency: You want to train a muscle as often as is beneficial. Think of it like protein intake: you wouldn’t eat your entire week’s worth of protein in one sitting. Similarly, you shouldn’t cram all your training volume for a muscle into one day and ignore it for the rest of the week.

How Often Should You Train a Muscle?

The “frequency debate” has been a hot topic in fitness. For years, the standard advice was to train a muscle hard once a week and let it rest. However, modern research paints a different picture.

A 2018 meta-analysis by Brad Schoenfeld found that when volume is equated (meaning the total amount of work is the same), training frequency makes little difference. However, in the real world, volume is rarely equated.

Spreading your work out over more days often allows you to perform higher quality volume. If you do 15 sets of chest in one day, your last 5 sets will likely be junk volume due to fatigue. If you split those sets across three days (5 sets per day), you can attack every set with higher intensity and fresher muscles.

The Research Consensus:

• 1x Per Week (Bro Split): Almost certainly suboptimal for maximum muscle growth
• 2x Per Week: The baseline “sweet spot.” Aim to hit every muscle group at least twice a week
• 3x+ Per Week: Potentially beneficial, especially for lower body training, as it may allow for higher total volume while managing fatigue

Ranking the Most Popular Workout Splits

Based on the science of frequency and recovery, here’s how the most common gym routines compare.

1. The Bro Split (Body Part Split)

Structure: Chest Monday, Back Tuesday, Shoulders Wednesday, etc.

The Science: This routine typically hits each muscle only once a week. According to Dr. Wolf, this approach should “very likely be avoided if your aim is maximum hypertrophy.” It simply doesn’t stimulate the muscle often enough to maximize growth.

2. Push / Pull / Legs (PPL)

Structure: Pushing muscles (Chest/Shoulders/Triceps), Pulling muscles (Back/Biceps), Legs.

The Science: This is a solid routine, but it has a major catch. To hit the optimal frequency of 2x per week per muscle, you must train 6 days a week (PPLPPL-Rest). If you miss days, your frequency drops below the effective threshold.

3. Upper / Lower Split

Structure: Upper Body days alternating with Lower Body days.

The Science: Excellent for those who can train 4 days a week. This guarantees you hit every muscle twice weekly. However, if you can only train 3 days, this split becomes suboptimal.

4. Full Body Split

Structure: Training the whole body in a single session, multiple times a week.

The Science: This may be the most flexible and effective approach for many natural lifters. It easily hits the 2x+ frequency threshold and allows you to manage fatigue better. By doing fewer sets per muscle per session but training them more often, you can often handle higher total training loads with better recovery.

The Checklist for Choosing Your Routine

If you’re unsure which routine to pick, use this checklist. The best routine for you is the one that meets these three criteria:

1. Enjoyment: You actually like doing it (consistency is key)
2. Frequency: It hits every muscle group at least twice a week
3. Performance: It allows you to perform the most volume while still seeing your strength maintain or increase week-to-week

If you’re currently on a bro split hitting chest once a week, the single best change you can make is increasing your frequency. For most lifters balancing work and life, a Full Body or Upper/Lower split usually offers the best balance of flexibility and optimal growth stimulus.

Track Your Volume Per Muscle Group

Whichever split you choose, the key is ensuring each muscle gets enough weekly volume (hard sets). Research suggests 10-20 hard sets per muscle group per week is optimal for most lifters.

SetsApart makes this simple to monitor. The Volume Per Muscle Group feature automatically tallies your hard sets for each muscle group across the week—regardless of which split you’re running. You can see at a glance if chest got 12 sets this week or only 6, and adjust accordingly.

This is especially valuable when running full body or upper/lower splits, where volume per muscle is distributed across multiple sessions and harder to track mentally.

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Source

This article was inspired by and summarizes key insights from the following video. Check out the video for more detail and subscribe to the channel—it’s a great resource for evidence-based training.

Watch the full video: Which Routine Builds the Most Muscle? (Science Explained)