Slide 1: Is testosterone responsible for the differences between sexes? Is it responsible for the differences in athletic performance between sexes?

Slide 2: Many international athletic leagues will now use serum testosterone cutoffs to determine who qualifies to compete as male or female.

Slide 3: But according to a BMJ review article, the serum cutoff value (5nmol/L) is arbitrary.
Serum testosterone concentrations, they note, β€œvary naturally in men and women, and across athletic states.”

Slide 4: These sorts of measures do not exist in a scientific vacuum. BMJ writes, β€œthe effect of these policies on individuals, societies, and even medical science has far reaching implications.” In this case, serum cutoffs will impact competitive athletes who already face discrimination along gender and race lines.

The Food For Thought

Is testosterone responsible for sexual differences in athletic performance? An international ruling on the case of runner Caster Semenya will require athletes to demonstrate testosterone levels within certain limits to compete as females, but the scientific rationale is dubious, raising ethical questions about the role of medicine defining identity.


  • Tannenbaum C and Bekker S. Sex, gender, and sports. BMJ. 2019 Mar 20;364:l1120. PMID 30894351.