The Study
Maximum Force Capacity of Back Extensor Muscles in Healthy Women and Men: Not Different, if Anthropometrically Normalized
This study compared how strong men and women are when lifting with their backs, and found that men are stronger overall — but when you adjust for how heavy their upper bodies are, they’re about equally strong. It’s like comparing how high two kids can jump — one is taller and heavier, so they jump higher, but when you adjust for size, they jump about the same relative to their own body. But this doesn’t mean being male or female causes you to be stronger — it just shows a pattern in this group.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Men are stronger in absolute terms, but when you compare strength relative to how heavy their upper body is, men and women are about equally strong.
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 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — if your back can lift twice your upper body weight, you're in the healthy range.
- 2Below 1.8 may mean your back is deconditioned, regardless of sex.
- 3Men: 241 Nm torque, 115 Nm upper body torque.
- 4Women: 162 Nm torque, 80 Nm upper body torque.
- 5Normalized ratio: men 2.16, women 2.00 — almost the same.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Functional Morphology and Kinesiology
Year
2026
Authors
Christoph Anders, Beatrice Steiniger, Florian Saenger, M. Marks, Lena Mader, Evgenij Dukvin, Anna Schneider
Related Content
Claims (6)
Among healthy, non-active adults aged 18–52, men produce 45% more maximal trunk extension torque than women, with average values of 241 Nm for men and 162 Nm for women, indicating higher absolute muscle force in men.
Sex differences explain 54% of how much force people can generate in trunk extension when measured in absolute terms, but only 2.8% of the force generated relative to upper body weight, meaning sex strongly affects total strength but not strength adjusted for body size.
When adjusted for body size, men and women aged 18–52 who are healthy and not physically active have similar back extensor strength relative to their upper body weight.
Back muscles in men and women can produce a force equal to about twice their upper body weight, based on the ratio of maximum torque they generate to their upper body weight.
A change of 0.2 in normalized trunk extensor torque is the smallest meaningful difference, and values below 1.8 are associated with measurable weakness in the back muscles.
People with a higher strength-to-weight ratio tend to have better overall health.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.