There's no fixed 'right' length for a workout — what matters is doing the planned work with real effort, not watching the clock.

holds up

No major exercise guideline (WHO, ACSM) prescribes an ideal session length; recommendations are built around cumulative weekly volume, not the duration of a single session.

noli's read

No major exercise guideline (WHO, ACSM) prescribes an ideal session length; recommendations are built around cumulative weekly volume, not the duration of a single session. A 45-minute and a 90-minute workout can deliver an equivalent training stimulus if the effective volume (sets close to failure, load, intensity) is comparable — raw duration is only a rough proxy. O'Hearn's framing correctly redirects attention toward effort rather than an arbitrary clock, and corrects a real myth ('you need X minutes'). Its blind spot: it says nothing about the minimum volume actually needed to progress — a short session with too few quality sets still won't cut it. The point holds as a corrective to a duration myth, but it's a general principle rather than an actionable protocol on its own.

the sources

Claimed by Mike O'Hearn. Noli grades the claim, never the person.

Decoded by Noli · August 3, 2026 · the original post

What the graded evidence says

Evidence: B+

Effect: muscle hypertrophy by weekly training frequency (volume-equated vs not) — no significant difference in hypertrophy between higher and lower frequency when weekly volume is equated (25-study meta); higher frequency favored only when it also raised total volume, and that effect was modest
Measured on: healthy trained and untrained adults

For a matched weekly volume, frequency is largely personal preference. Training twice or more per week is at least as effective as once, and can make it easier to accumulate volume with good technique.

Mike O'Hearn in the Register1 claims gradedSee their record →

Noli has read similar claims

Other advice in the Register that leans on the same research.

Significantly reducing training volume (to approximately 6 hard sets per muscle group per week) while maintaining high intensity allows for excellent body composition results, even during a cutting phase.

holds upJeff Nippard

Drastically reducing training volume (1-2 working sets per exercise) while maintaining high intensity is an effective strategy for preserving muscle mass and strength during a caloric deficit.

holds upJeff Nippard

A complete 3x/week program (6 compound exercises + 1-2 accessories) is enough for most people; women generally tolerate higher reps better than men; adjust exercises to your body structure.

holds upJeremy Ethier, BKin

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