A new way of measuring workout volume—by giving less weight to exercises that are not the main focus—better predicts muscle growth and strength gains than simply counting all sets. This suggests that...

Pro

Against

Mechanism

Synthesis from 1 study

How it works

Direct exercises like bicep curls put more strain on the muscle than indirect ones like pull-ups, which triggers stronger signals for muscle growth. The fractional method gives indirect sets half the credit because they don’t stimulate the muscle as effectively—this matches what’s seen in...

Most probable mechanism

In Simple Terms

When you do exercises that directly work a muscle—like bicep curls—the muscle gets more fully stretched and squeezed, which sends stronger signals to the nervous system to recruit more muscle fibers. This leads to more force and damage in the muscle fibers, which triggers growth and strength gains. Exercises that only partly involve the muscle—like pull-ups for the biceps—don’t create the same level of tension, so they contribute less to growth. This is why counting only direct sets, or giving indirect sets half the weight, better predicts results—because not all muscle movement is equal. This is supported by findings in 10.1007/s40279-025-02344-w.

Causal chain

Direct resistance exercises generate higher mechanical tension and muscle fiber strain in the target muscle compared to indirect exercises, as demonstrated by greater electromyographic activation and muscle length changes during isolated movements.

Supported by evidence

which leads to

Increased mechanical tension in the target muscle activates intracellular signaling pathways—such as mTOR and MAPK—that initiate protein synthesis and muscle fiber remodeling.

Indirect evidence only

which leads to

The cumulative effect of higher tension from direct sets leads to greater net muscle protein balance and structural adaptation over time, while indirect sets contribute minimally due to lower target muscle recruitment and mechanical load.

Supported by evidence

Evidence from Studies

Supporting (1)

Community contributions welcome

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

Systematic Review With Meta-Analysis

Human

2026 Feb

Contradicting (0)

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

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

Score: 39

DOI: 10.1007/s40279-025-02344-w

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