What Grows and What Doesn't: The Variables Behind Hypertrophy

Opener

Every lifter has a list of things they think builds muscle. Split or full body. Morning or night. Slow reps. Heavy weights. Linear or undulating. Most of that list gets argued about far more than it deserves.

Some of those variables are levers. Some are just preferences. If you can't tell the two apart, you'll spend your energy on the wrong thing.

A 2022 umbrella review sorted them.

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1. What an umbrella review is

A single study tells you what happened to one group of people. A meta-analysis pools a stack of studies on one question. An umbrella review goes one level higher and pools the meta-analyses themselves.

This one started with 52 meta-analyses and kept the 14 that met its criteria. Those 14 covered 178 primary studies and roughly 4,700 healthy, physically active adults. Nine were rated high quality and the other five moderate.

So the question isn't "what did one lab find?" It's "what holds up when you look at the whole body of evidence at once?"

2. Volume is the lever

Volume was the only variable with a dose-response relationship to muscle growth. More hard weekly sets, more growth, up to a point.