The Study
Relationship Between Muscle Swelling and Hypertrophy Induced by Resistance Training
This study watched a group of young men doing leg exercises and measured how much their muscles swelled right after the first workout and how much bigger their muscles got after 6 weeks. It found that those who had more swelling early on tended to gain more muscle later — but it doesn’t prove the swelling caused the growth.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Scientists wanted to see if getting a big 'pump' during your first workout means you'll gain more muscle over time. They measured leg muscle size before and after the first workout, and again after 6 weeks of training.
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 531 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The results suggest that how much your muscle swells right after a workout might predict how much it grows over weeks of training.
- 2After the first workout, muscles were 8.3% thicker.
- 3After 6 weeks, they were 2.9% thicker.
- 4People who had more swelling after the first workout tended to gain more muscle overall.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Strength and Conditioning Research
Year
2020
Authors
Tetsuya Hirono, T. Ikezoe, M. Taniguchi, Hiroki Tanaka, J. Saeki, Masahide Yagi, J. Umehara, N. Ichihashi
Related Content
Claims (4)
That muscle 'pump' you feel when lifting weights? It might feel like growth, but this claim says it doesn't actually cause your muscles to get bigger over time.
If a guy new to lifting weights gets a bigger muscle swell right after his first workout, he’s likely to gain more muscle over the next 6 weeks.
Lifting weights (3 sets of 8 reps at 80% of your max) three times a week for six weeks can increase the thickness of thigh muscles in young men who haven't trained before by about 2.9%.
After just one leg workout, the muscles in young men's thighs get temporarily thicker by about 8%, which is likely due to fluid buildup from the workout. This finding is from the abstract summary - full study details were not available.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.