Training & movement
B · Reasonable confidenceNew this roundDoes it matter how fast you perform a repetition?
Original title: How slow should a repetition be? Repetition tempo and hypertrophy
What this means
Barely: faster and slower lifting produced comparable muscle growth, with a trivial difference of 0.09 (95% credible interval −0.04 to 0.22).
Enes A, Piñero A, Hermann T, Zamanzadeh A, Hennessy T, Montenegro D, Parnell C, Jia A, Weitzman T, Wolf M, Korakakis PA, Swinton PA, Schoenfeld BJ · 2025 · Journal of Strength and Conditioning Research 39(12):1331-1339
What does this rating mean?
A solid systematic review with caveats, or consistent indications with a limited scope.
Findings
Fourteen studies compared a slower tempo (1.7 to 4.5 seconds per repetition, averaging about 3.5 seconds) with a faster one (0.3 to 2 seconds, averaging about 1 second), holding all other training variables constant. Within-group growth was comparable (faster 0.43, 95% CrI 0.29 to 0.58; slower 0.34, 95% CrI 0.22 to 0.47). The pairwise difference was trivial and slightly favoured the faster tempo (0.09, 95% CrI −0.04 to 0.22), with a low probability that the difference is even small (p = 0.450).
Who this applies to
Healthy adults who strength train, in studies where all other training variables were held constant.
Size of the research
Fourteen studies comparing tempos of roughly one second with tempos of roughly 3.5 seconds per repetition.
What to keep in mind
Differences may still emerge under specific conditions; the certainty of the estimates varied across sub-analyses.
Practical conclusion for REZA
Tempo is not a dial with much hypertrophy behind it. Controlled movement stays in REZA's coaching for other reasons; prescribing a precise tempo is not needed to drive muscle growth.
View method and source
Methodology
Systematic review with Bayesian meta-analysis
Limitations
Subgroup analyses by muscle action (eccentric or concentric), body region (upper or lower) and training to failure produced trivial to small effects, with certainty varying by analysis. The journal issue is dated December 2025; the record was indexed in PubMed on 8 September 2026.
Original source
DOI: 10.1519/JSC.0000000000005302 · PMID: 42709703
View on PubMed →