The Study
Does Varying Repetition Tempo in a Single-Joint Lower Body Exercise Augment Muscle Size and Strength in Resistance-Trained Men?
This study compared two ways of lifting weights—slow vs. fast—and found that both made muscles stronger and bigger in similar ways, but fast lifting might have made one small part of the thigh muscle a tiny bit bigger. It doesn’t prove fast lifting is better overall—it just hints at a small difference under very specific conditions.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Two guys trained their legs differently: one slowed down the lowering part of leg extensions, the other kept it fast — same number of reps and weight. After 8 weeks, both legs got stronger and thicker, but the fast-lowering leg got a tiny bit more muscle in the lower part.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 559 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The difference in muscle growth is small — about the width of a pencil — and only in one part of the thigh.
- 2For most people, it won’t matter much, but bodybuilders might care.
- 3Fast tempo: distal quad grew 5.5% (0.23 cm); slow tempo: distal quad grew 2.2% (0.13 cm).
- 4Both legs got 17–22% stronger.
- 5Slow tempo felt harder (RPE 8.59 vs 7.98).
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Strength and Conditioning Research
Year
2021
Authors
Jeremy R. Pearson, Tanuj Wadhi, Christopher Barakat, D. Aube, B. Schoenfeld, J. Andersen, R. Barroso, C. Ugrinowitsch, E. D. De Souza
Related Content
Claims (7)
In men trained in resistance exercise, performing leg extensions with a faster lowering phase for 8 weeks increases the thickness of the lower part of the quadriceps muscle by 5.5% compared to a slower lowering phase, when total workload and intensity are kept the same.
In men who regularly lift weights, using fast eccentric movements during leg exercises leads to more muscle growth in the lower part of the quadriceps than in the upper part, even when total muscle size and strength remain unchanged.
In resistance-trained men, performing leg extensions with a slow lowering phase increases the feeling of effort compared to a fast lowering phase, even when the total work and weight lifted are the same, and this does not lead to greater muscle growth or strength gains.
In men who regularly lift weights, doing single-leg extension exercises twice a week for eight weeks leads to a 17–22% increase in maximal strength and a 2–5% increase in muscle thickness.
In men who regularly lift weights, performing leg extensions with a fast or slow lowering phase for 8 weeks leads to the same amount of muscle thickening in the upper thigh and the same increase in maximum strength.
When lifting weights with slow, controlled movements—10 seconds up and 4 seconds down—muscle growth is lower than when using faster, standard tempos of 1–2 seconds up and 1–2 seconds down, provided the total workload and effort are the same.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.