Testosterone boosts women's athletic performance, study shows | Science | The Guardian

Good morning all,

During our recent EMG lab, we considered muscle structure/function, and how muscle strength can be improved through enlargement of muscle fibers.  We also noted that testosterone can support the development of larger muscles in both men and women.  In the news this week is a report confirming that testosterone improves muscle and athletic performance in women, along with news of a strict limit on testosterone in female athletes being imposed by a track-and-field regulatory body.

Testosterone is a potent steroid hormone, produced in abundance by the male gonads (the testes).  Testosterone is also found in women.  The female gonads (ovaries) do not produce testosterone directly, but do produce several estrogens, which can be converted to testosterone by enzymes (especially in the brain).  Both sexes also produce other androgens (male-typical hormones) in the adrenal glands, which also can be converted into testosterone.

So, we tend to think of testosterone as a 'male hormone', but the reality is not so simple.  Both women and men have circulating testosterone, although men typically have levels that are 10-30x higher that those found in women.  But, here too, our simplistic and convenient categorizations are not always reflected in reality.

While men typically have much more testosterone in circulation than do women, the range of variation in each gender is large.  What of women who produce unusually large amounts of testosterone?  Will that give them a muscular and a competitive advantage in sporting events?  The anecdotal and the experimental evidence say that it will. 

It is convenient to think of all persons as being purely binary in terms of their sex, such that all aspects of their sexual make-up (genetic sex, physical sex, physiological sex, gender identity) align to be either purely female or purely male, but the reality is, as always, more complicated.  Persons of differential sexual development may not be perfectly aligned in all of their sexual characteristics, causing them to have characteristics which are not purely 100% typical of one gender or another.  Apart from the social and physical challenges this poses, how such individuals can be evaluated in regulated sporting events recently has come into question.  The most notable case has been that of the South African athlete Caster Semenya, a multi-medal winning foot race champion who has repeatedly been sanctioned because her testosterone levels are higher than the thresholds set for female athletes.

And what of athletes that are making a gender transition? Their testosterone levels are highly variable, and may fall within the male-typical or the female-typical range.  Should they be barred from, or limited in, participation in sporting events?

These are important issues, beyond sporting regulation.  Most aspects of society long have been male-biased, and it is becoming increasingly apparent that we suffer because of this.  In science, it has become very clear that work done largely on male physiology serve females poorly.  For decades, the standard experimental models for human physiology have been male mice and rats.  Only one gender was used in order to reduce experimental variability.  We long have known of differences in the female and male reproductive systems, but we never really appreciated how their influences translate into other systems (including the muscular system).  But, now we are learning how surprisingly different male and female physiology outside of reproductive systems can be.  And, the fact that this recent study of testosterone supplements in women was one of the first of its kind suggests that we have a lot of catching-up to do: 

https://www.theguardian.com/science/2019/oct/15/testosterone-boosts-womens-athletic-performance-study-shows

There is much to be learned about differences in female and male physiology and their implications for our health and well-being, and our scientific community is finally waking up to this fact.  How the sporting community deals with the complexities of our physiology is of relatively little importance, perhaps.  But the issue of equality in general, in science, health, and society, is one that recent generations have failed to properly address.  May your generation be more open, more mindful, and more egalitarian.

Have a great weekend -
Dr. Nealen