REF-583 · Grgic, Schoenfeld, Davies, Lazinica, Krieger & Pedisic, 2018 · Sports Medicine, · Paper · PubMed
Resistance-training frequency & gains in muscular STRENGTH
Meta-analysis (frequency effect is a volume artifact)
Key Findings
Unadjusted, strength gains rose with frequency (pooled ES 0.74/0.82/0.93/1.08 for 1/2/3/4+ sessions/wk; overall p=0.003).
Volume-equated: frequency had NO significant effect on strength (p=0.421) — the apparent benefit is a vehicle for more volume.
Higher frequency helped more for multi-joint upper-body lifts and in women; young > older responders.
Practical Application
Prescribe the weekly strength VOLUME first; split it across whatever session count fits around endurance — 1 dense session ≈ 2–3 lighter ones at equal volume for the strength outcome.
Time-crunched endurance athlete: don't chase high strength frequency for its own sake; add sessions only to bank more total volume without hurting recovery/interference.
Limitations
Mostly untrained participants (trained data scarce); volume-equated designs can't capture that higher frequency usually IS how you achieve higher volume.
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