The more you work each muscle group per week—with the right exercises that really engage the muscle—the more your muscles will grow, and this is the #1 thing that matters for building muscle.

From: The Top 3 Reasons You’re Not Gaining Muscle

Likely supported

Evidence leans toward this claim being true.

39
Pro
32
Against
causal
4 studies

Not medical advice. For informational purposes only. Always consult a healthcare professional.

What this claim means

The more you work each muscle group per week—with the right exercises that really engage the muscle—the more your muscles will grow, and this is the #1 thing that matters for building muscle.

See the technical phrasing

Weekly effective volume, defined as the total number of sets performed per muscle group weighted by the relative contribution of each exercise to muscle activation, is the primary determinant of muscle hypertrophy in humans.

Why this might work
Supported
based on 4 studies

When you do sets of exercises that strongly activate a muscle group, the tension and burn from the effort trigger signals inside muscle cells that tell them to build more protein, making the muscle bigger over time — and doing more of these effective sets each week leads to more growth, as shown in studies like 10.1007/s40279-025-02344-w, though too many sets may not add more benefit, as seen in 10.1123/ijspp.2018-0914.

What the research says

Supports

2 studies

39

Study: The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains.

This study provides evidence supporting the claim.

Contradicts

2 studies

32

Study: Muscle Hypertrophy Responses to Changes in Training Volume: A Retrospective Analysis

This study provides evidence contradicting the claim.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 4 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.