A narrative review published by Van Every, Lim, Wolfe, Nippard, and Phillips critically examined several popular but poorly supported theories about what truly drives muscle growth.
Modern-day fitness often focuses on optimization, and with that we sometimes lose sight of the things that really matter. It’s “shiny object syndrome”, except with programming techniques and fancy exercises instead of hobbies and ideas.
Backed by scientific research, the review debunks three myths about muscle growth.
Myth 1 – Post-Workout Hormone Spikes Play a Factor
After a hard workout you will experience a surge in testosterone, growth hormone, and IGF-1. However, evidence suggests that this is mainly a byproduct of resistance training rather than an actual link to muscle growth.
In addition, these hormonal spikes are short-lived.
Myth 2 – The “Pump” Directly Causes Muscle Growth
As Arnold Schwarzenegger proclaimed in Pumping Iron, the greatest feeling in the gym is the pump. Blood rushes to the muscle and your skin gets tighter as you admire this temporary state in the mirror.
Unfortunately, this has little bearing on muscle growth. Cell swelling, as it’s referred to in literature, has a weak at best correlation with hypertrophy. Other factors are far more important.
Myth 3 – Metabolic Stress (i.e. The Burn) Leads to Muscle Growth
Metabolic stress and the pump often go hand-in-hand. A high repetition set, superset, or circuit style training leaves your muscles full of blood coupled with the burning sensation known as metabolic stress.
This burn is the result of an accumulation of metabolites, which some have theorized can signal muscle growth. Unfortunately the research says otherwise.
Part of the reason this theory falls short is because endurance training causes a similar response, and we know that this type of training is not conducive to building muscle.
(Photo by Owen Humphreys – PA Images/PA Images via Getty Images)
What Actually Builds Muscle
Now that we’ve cleared the air on some of the misconceptions around muscle building, let’s get to the real driver of hypertrophy. The answer is simpler than you think, and this simplicity explains why it can be overlooked.
Mechanical tension is the primary driver of muscle growth.
In simple terms, mechanical tension means putting the muscle under sufficient resistance, forcing it to adapt and grow. This could be dumbbells, barbells, kettlebells, cables, machines, whatever.
Mechanical tension requires enough resistance so that the exercise is challenging, and good form to ensure that the target muscle is being worked effectively. This fundamental principle has stood the test of time, not only through anecdotal evidence but scientific research as well.
The good news is that you don’t have to chase fancy training routines or try to create the perfectly optimal hormonal environment.
An important aspect of mechanical tension is that it changes. A weight that was challenging to you as a beginner will become easier as time goes by. You can’t expect the same results unless you progress, whether it’s more weight, more reps, or both.
Fundamentals aren’t sexy. They aren’t new. They aren’t exciting. But they work.
This story was originally published by Men’s Fitness on Feb 19, 2026, where it first appeared in the News section. Add Men’s Fitness as a Preferred Source by clicking here.