Training frequency (sessions per muscle per week)
When weekly volume is the same, how many days you split it across makes little difference to muscle growth. Frequency is mainly a tool to fit in your volume with good quality sets; for strength, practising a lift more often gives a small extra edge.
What the science says
- With equal volume, frequency barely affects growth Strong evidence
Schoenfeld et al.'s 2019 meta-analysis concluded there is strong evidence that, when volume is equated, training frequency does not meaningfully change hypertrophy, including in trained people. Pelland et al.'s 2026 meta-regression likewise found frequency's effect on hypertrophy compatible with negligible.
- Higher frequency helps when it adds volume Moderate evidence
In studies where volume was not equated, Schoenfeld et al. (2019) found higher frequencies gave a modest advantage, most plausibly because more sessions allowed more total sets.
- Practising a lift more often helps strength a little Moderate evidence
Grgic et al.'s 2018 meta-analysis found strength gains rose with frequency, but not when volume was equated. Pelland et al. (2026) did find a reliable positive effect of frequency on strength, consistent with strength being a skill that benefits from practice.
How to apply it
Pick a frequency that lets you complete your weekly sets with good effort; for most people that means training each muscle about twice a week.
Who should be careful
Higher frequency leaves less recovery between sessions for the same muscles and joints; if soreness or joint pain carries into the next session, spread the work out or cut volume. People with injuries or medical conditions should get an individual plan from a qualified professional.
Frequently asked questions
Is training a muscle twice a week better than once?
Not by itself. When weekly volume is the same, meta-analyses find no meaningful difference in growth. Twice a week is simply a practical way to fit in enough quality sets.
Is a bro split (one muscle per day) bad?
No, as long as you reach your weekly volume with good effort. The catch is that putting all of a muscle's sets in one session can lower the quality of the later sets.
Does frequency matter for strength?
A little. Practising a lift more often gave a small extra strength benefit in a 2026 meta-regression, so 2–3 sessions per week on your main lifts is sensible.
Scientific references
- How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency
- Effect of Resistance Training Frequency on Gains in Muscular Strength: A Systematic Review and Meta-Analysis
- The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains
More training variables
- Rest intervals between sets Moderate evidence
Very short rests (under about a minute) tend to cost you reps and slightly blunt growth; past about 90 seconds, extra rest brings little added hypertrophy.
- Load and rep range (heavy vs light) Strong evidence
Muscle grows similarly across a wide range of loads, from heavy sets of 5 to light sets of 30, as long as sets are taken close to failure.
- Proximity to failure (reps in reserve) Moderate evidence
Sets need to be hard to drive growth, and hypertrophy tends to rise the closer you get to failure.
- Repetition tempo (time under tension) Limited evidence
Deliberately slowing your reps to maximize 'time under tension' does not build more muscle.
- Range of motion (full vs partial reps) Moderate evidence
Full range of motion generally builds more strength and lower-body muscle than short, partial reps.
- Progressive overload Moderate evidence
To keep improving, training has to get gradually harder over time, by adding weight, reps or sets.