Analysis Version
v1
History
Back to Study: Sex differences in absolute and relative changes i...
quantitative
Analysis v1
39
Pro
0
Against

When men and women do strength training, men tend to build more upper-body muscle than women do, and this difference is bigger in the upper body than in the legs—probably because men start out with more upper-body muscle to begin with.

Claim Language

Language Strength

probability

Uses probability language (may, likely, can)

The claim uses 'likely due to', which indicates a probable explanation rather than a definitive cause. The verb 'shows' is neutral but paired with 'likely' to express likelihood, not certainty.

Context Details

Domain

exercise_science

Population

human

Subject

Upper-body muscle growth following resistance training in males compared to females

Action

shows

Target

a greater absolute advantage in males compared to females (SMD = 0.30) than lower-body growth (SMD = 0.17)

Intervention Details

Type: exercise

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Evidence from Studies

Supporting (1)

39
39

Sex differences in absolute and relative changes in muscle size following resistance training in healthy adults: a systematic review with Bayesian meta-analysis

Systematic Review With Meta-Analysis
Human
2025

The study found that men gain more upper-body muscle than women after weight training, more so than in their legs — just like the claim says. The numbers are a little different, but the overall pattern matches.

Contradicting (0)

0
No contradicting evidence found

Source Study

Sex differences in absolute and relative changes in muscle size following resistance training in healthy adults: a systematic review with Bayesian meta-analysis

Score: 39
DOI: 10.7717/peerj.19042

Similar Assertions

Men tend to gain a little more muscle than women from weight training, not because their muscles grow better, but because they start with more muscle to begin with.

39
0
82%

When men and women in their late teens to mid-40s do strength training, they both gain muscle at about the same rate—men might gain a tiny bit more, but it’s so small it doesn’t really mean one sex builds muscle better than the other.

39
0
79%

One study with women showed a much bigger muscle growth difference than the others — all of which were only with men — suggesting sex might matter, but we need more studies to know for sure.

0
39
77%

Men and women gain muscle at about the same relative rate when they train the same way—women just start with less muscle, so they gain less in absolute numbers.

0
0
77%

Whether you're male or female, if you lift weights, you're likely to gain muscle and strength at about the same rate — even though guys usually start with more testosterone than girls.

0
0
76%