More or Less (BBC Radio 4):

"Transgender women in sport: Does ‘comparable’ mean ‘equal’?"
Date: March 14, 2026
Host: Charlotte MacDonald
Guests: Tom Coles, Professor Alan Williams, Dr. Bruno Gualano

Episode Overview

This episode of More or Less examines the contentious debate over transgender women’s participation in women’s sports, focusing on a recent systematic review published in the British Journal of Sports Medicine. The hosts scrutinize what the review truly found concerning the physical fitness of transgender women versus cisgender women, question the strength of the data, discuss misunderstandings in the media, and explore what science can – and cannot – currently tell us about fairness in sporting competition.

Key Discussion Points & Insights

1. Background: The Sex Divide in Sports

• Charlotte MacDonald opens by explaining how, aside from a few mixed events, the Winter Olympics demonstrated the norm of men and women competing separately, usually justified by clear physical differences such as speed, strength, and endurance.
  • (01:17) “Generally, in sport, that is what we consider fair because ... men are faster, more powerful and have greater endurance.”

2. The Study’s Headline: ‘Comparable’ Physical Fitness

• The episode discusses a new systematic review summarized in the media as showing that transgender women have no sporting advantage over cisgender women.

  • (02:19) The term “cisgender” is clarified as referring to women assigned female at birth.

• Tom Coles calls attention to the way the study’s findings were communicated:

  • (02:31) “‘Trans Women in Sport have no advantage over CIS women, study finds’ ... But is this what the study in question really found?”

3. What Did the Scientists Actually Measure?

• The featured research is a systematic review:

  • It collates existing studies comparing physical characteristics and fitness between transgender women and cisgender women.
  • Importantly, it did not conduct new physical tests.

• The review found that transgender women had somewhat more lean mass (muscle) but asserts that their overall “physical fitness” (a bundle of measures including strength and endurance) is “comparable” to cisgender women.

  • Professor Alan Williams points out that, generally, more muscle should correlate to more strength, so this conclusion is counterintuitive.
    • (04:10) “Alan says that that’s counterintuitive, as you’d expect people with more muscle to be stronger.”

4. Flawed Comparisons in Existing Studies

• The example of a Brazilian volleyball study is examined:

  • Only 7–8 participants per group; transgender women trained 4 hours/week, cisgender women 14 hours/week.
  • The transgender women’s group was also shorter, lighter, older, and competed at a lower level.

• Professor Alan Williams:

  • (05:48) “There’s a mountain of evidence that physical training affects these things... if one group is training more than three times more than the other group, we can safely assume that that is affecting the results.”

• Tom Coles underscores that these mismatches undermine meaningful comparison.

5. Statistical Significance vs. Real Differences

• The systematic review lumps together such studies; three out of four showed transgender women stronger, but none found a statistically significant difference.

  • However, the confidence in these findings was “very low” due to poor study quality and small group sizes.

• Charlotte MacDonald:

  • (07:03) “Saying they haven’t found a statistically significant difference isn’t the same as saying there’s no difference, especially when the controls aren’t in place to ensure you’re doing a fair comparison.”

6. Types of Studies: Cross-sectional vs. Longitudinal

• Most included studies were cross-sectional (snapshot at a single point), not tracking changes over time.

• Tom Coles notes what’s really needed are longitudinal studies following transgender women from the onset of hormone treatment to see real long-term physiological effects.

• There are “a handful” of such longitudinal studies, but these show only minor decreases in muscle and strength—or sometimes none at all.

  • Professor Alan Williams:
    • (07:56) “Small increases in body fat and a small reduction in muscle mass and a small reduction in muscle strength, or in several respects, there were no changes.”

• After three years, there wasn’t enough data to analyze absolute muscle mass, upper/lower-body strength, or endurance with confidence.

  • (08:08)

7. Scrutiny of the Conclusion: Is ‘Comparable’ the Right Word?

• So, why did the study describe the groups as ‘comparable’?
  • Professor Alan Williams:
    • (08:26) “My opinion is there are reasons why people haven’t done a systematic review like this before, and that is because there wasn’t a need for a systematic review of such poor evidence. To proceed with a systematic review and conclude then what they have, while partly acknowledging how poor the evidence is, but then be so clear in apparent conclusions is very strange.”

8. What Do the Study’s Authors Say?

• Tom Coles relays feedback from study co-author Dr. Bruno Gualano:

  • The term 'comparable' does not mean the two groups are “the same”; it means no statistically significant differences were found in the existing (imperfect) data.
  • He agrees that high-quality, well-controlled, long-term studies with trained athletes are needed and that their paper calls for exactly that.

• Tom Coles:

  • (08:57) “He says that this description of the groups being comparable should not be taken as meaning the two groups are the same. That interpretation is wrong. It’s rather describing the fact that the analysis did not find statistically significant differences between the groups.”
  • (09:55) “Our paper calls for exactly that” [well-controlled longitudinal studies].

Notable Quotes & Memorable Moments

• Charlotte MacDonald on the complexity of the issue:
  • (07:03) “Saying they haven’t found a statistically significant difference isn’t the same as saying there’s no difference...”
• Professor Alan Williams on poor evidence:
  • (08:26) “To proceed with a systematic review and conclude then what they have, while partly acknowledging how poor the evidence is, but then be so clear in apparent conclusions is very strange.”
• Dr. Bruno Gualano (via Tom Coles), urging better research:
  • (08:57) “The analysis did not find statistically significant differences... but women well controlled longer term studies, especially in trained athletic populations, would be definitive.”

Timestamps for Key Segments

• 01:17 – Introduction & framing the issue (sex differences in sport)
• 02:10–02:44 – Headlines vs. the study’s actual claims; systematic review explained
• 05:00–06:20 – Problems with study comparability (Brazil volleyball study)
• 07:00–07:40 – Statistical significance vs. real-world difference; need for better study design
• 07:44–08:20 – Limited longitudinal evidence
• 08:25–08:57 – Scrutiny of review’s conclusion; speaking with study authors

Conclusion

The More or Less team concludes that the current evidence base for comparing the athletic capacity of transgender women and cisgender women is poor and limited. The systematic review in question provides no clear evidence that the groups are “equal” in sporting terms; rather, it simply did not detect statistically significant differences within the flawed and insufficient available studies. Both critics and the study’s authors agree: robust, long-term, and well-controlled research involving trained athletes is desperately needed to answer these questions more definitively.

Episode takeaway:
Media headlines may overstate or misrepresent the nuanced, limited findings of systematic reviews in this area. The debate cannot be settled until better, more precise and relevant data is produced.