PHRF for Humans? A Modest Proposal for non-Binary Fairness in Sports

9 min readMar 29, 2022

A dinghy class race for a fleet of RS Aeros

There seems to be a whole lot of argle-bargle going on right now about “trans women in sports,” i.e. whether M-to-F trans people should be allowed to compete in “women’s” sports.

On the one side is the passionate advocacy of the trans community that one’s gender self-definition should be officially accepted as a fundamental civil right — on passports and other documents, and in all legal contexts. So a M-to-F trans person, they say, is and should be a woman for all possible legal purposes… including sports leagues. To bar a trans woman from participating in “women’s sports” is to deny her gender identity.

On the other side are those who argue that — sex and gender being what they are (a committee decision by many different factors in our developmental physiology, neurology, etc) — some people may strongly identify as female while still having some “male” physiological markers such as longer bones, greater upper body strength, higher muscle/mass ratio. This, they say, could potentially make it unfair for people with such characteristics to compete against “regular women,” i.e. those who were officially identified as female at birth and may lack these “male markers.”

Both these arguments have merit; but it seems to me that the second argument founders rather quickly on the sheer biological and gender diversity of humankind, even without the existence of people who explicitly challenge or reject their officially assigned gender. Biological sex, let us say it again, is a committee decision made by a very large committee of developmental factors. It is not a simple SPST switch.

To take just one well-documented instance of gender complexity: an AIS female is a person with the semi-rare “androgen insensitivity syndrome” occurring in approximately 1 in every 20,000 live births. This person is a chromosomal male (XY) who, due to a genetic variation, does not respond to androgens during development. As a result: testicles never descend, body hair is female-pattern rather than male-pattern, the vagina if it exists may be vestigial, and in “complete” cases the penis does not develop. Babies with AIS are usually officially “sexed” as female at birth, and sometimes the condition is not detected until adolescence or even later.

An AIS female has no uterus or ovaries, never menstruates, and may often be taller than the average for females of her ethnicity. The arm and leg bones may be longer, shoulders wider, muscle mass ratio a little higher. These attributes could be seen as advantageous to an athlete. So here we have an unquestioned “woman,” accepted by medical convention as legally female despite the XY chromosome pattern, usually comfortable with that gender identity and not questioning it, who is not banned from competing in women’s sports yet may have some of the advantages claimed for transitioned females.

Here’s another confound to simple gender binaries. Women assigned as female at birth and female self-identified — with XX chromosomes — may also have higher than average testosterone levels due to random genetic variation. A topical instance is the case of Caster Semenya who was recently barred from competing in women’s sports. Though her elevated testosterone is a naturally-occurring (though rare) condition, she was told she would have to take drugs to reduce it before the Olympic Committee would allow her to compete. She was not considered “female enough” to compete with other women, despite her XX chromosomes and female self-identification.

I hope these two ‘edge cases’ demonstrate how very complex the developmental story is for biological sex and social gender. There is a tremendous variation among individuals, whether chromosomally male or female, in the suite of associated characteristics that are considered “normal” for their chromosomal sex. Some men have unusually low testosterone, little body hair, a much reduced incidence of age-related baldness, lower aggression, lower sperm counts, lower muscle mass, etc. Some women (like the unfortunate Semenya) have unusually high testosterone.

Testosterone (and steroids generally) is considered advantageous in athletics because it seems to facilitate a larger body, higher muscle mass ratio, and faster, heavier muscle development from training. This gives biologically “normal” men an advantage over biologically “normal” women in most sports due to height, muscle density, reach, etc. And this is why we have traditionally separated sports leagues into male and female divisions: open competition between average male athletes and average female athletes would favour the male athletes almost every time (there are exceptions such as some gymnastics feats for which lighter musculature, a lower centre of gravity and more compact, agile body types offer an advantage).

In athletics, “edge case” men (low testosterone chromosomal males identified as male at birth) tend to be selected out early on. Those who win competitions tend to be those with the traditional biological male advantages of reach, height, muscle mass etc. So on average, athletics selects for “cis” males with higher testosterone and traditional “masculine” physiques.

Athletics also selects for “edge case” women whose physiques and capabilities can be trained to be more “masculine” in terms of strength, speed, etc. The most stereotypically cis-female woman with lower muscle mass, higher body fat (‘curvaceous’ as such bodies are often condescendingly described), and shorter more fragile bones is less likely to excel notably at athletics and to pursue it as a career.

So the women who reach the very top of the athletic world are likely to be outliers — not only in their sheer determination and discipline, but also in deviating to some greater or lesser degree from patriarchal norms of femininity and canonical biological “femaleness.” For a start, women who train really rigorously for high-intensity athletics often cease to menstruate. The stress of a high-performance training regimen interferes with the reproductive capacity that is often mooted as the very “definition of womanhood.”

Where does this leave us? With such a wide variety of physical capabilities among legally-defined “women” and legally-defined “men,” how do we ensure that sporting competitions are fair? I have a modest proposal, based on some years spent in sailboat racing.

[Sailboat racing? Yes, well, hear me out. Maybe it’s a crazy idea, or maybe not.]

The physics of sailboats is such that every boat’s top speed is limited by its waterline length (root 2 times the square root of the WLL, if you enjoy such details). What this means: bigger boats can go faster than smaller boats.

Hull design also strongly limits or enhances top speed. Multihulls (catamarans and trimarans), with very shoal draft (minimal wetted surface) can go much faster than most monohulls (conventional sailboats). Sail area and design of rig also limit or enhance top speed. Old fashioned low-aspect rigs with cloth sails will never perform like a high-aspect rig with modern molded Kevlar sails. Marconi sloops always outperform gaff rigs upwind. And so on.

To cope with this bewildering variety, there are basically two kinds of sailboat racing. One is called a “class race”, in which only boats of one standard design are permitted and all boats must be exactly the same (sail area, number of crew, etc). These restrictions eliminate variation and ensure that the race is “apples and apples” — winning is determined by the skill and ability of the crew rather than the innate capability of their craft.

In the other kind of race — the more casual, amateur, yacht-club regatta or “Wednesday night bash” — there is a random mix of widely different styles, sizes, and ages of boat. If it were just a drag race, the skippers with the biggest, best-designed boats would always win… and there would be no point to it. It would be a race of money instead of skill. Anyone with the means could just buy the victory.

So in the mixed boat racing world, every boat is assigned a handicap based on a standardised set of measurements and analytics (all the factors I mentioned above that enhance or limit top speed, but in very fine detail). This is called its PHRF number. Basically, larger numbers mean slower boats, smaller numbers mean faster boats. The PHRF numbers mean that each boat’s finish time can be adjusted based on its inherent performance characteristics. So the boat that finishes the race in the fewest hours or minutes is not necessarily the winner: the winner is the boat that pushes the limits of its design the hardest, lives up to its theoretical ideal performance, and hence out-performs the rest.

I myself have witnessed an aging Cal 25 (a cheap, scruffy old plastic classic from the 80’s) win a regatta against state-of-the-art racing machines 30 years newer. The old Cal’s crew simply sailed better.

The way we do human athletic “divisions” (sets of people who are allowed to compete against one another in the same event) seems foolishly binary to me. We divide them by assigned gender: men’s events and women’s events. It’s as if all of sailboat racing were reduced to “monos vs multis,” and nothing else was taken into account. Whereas multis range from skittering 16.5 ft Hobie Cats, to lumbering Catfisher 32’s, to 50-foot luxury cruising cats, to professional offshore racing cats, to homebuilt plywood trimarans, to high-tech racing trimarans…. and monohulls vary tremendously as well.

In fact, the category of monos vary amongst themselves at least as much as people classified as “women” vary from one another, and the category of multis vary at least as much as people classified as “men.” Which is why we have PHRF — so that everyone can compete fairly in one event despite all this richness of variety.

My modest proposal is that human athletes could be measured and rated on a set of attributes and analytics, just like sailboats. Just off the top of my head, we could measure: blood oxygen levels resting and under stress, resting and stressed heart rate, lung capacity and spirometry, bone density, weight to muscle mass ratio, muscle mass distribution, BMI, weight lifting capacity, reflex speeds, height, reach, age, etc. Then we could assign each individual their very own PHRF number (which of course would need to be updated regularly, prior to sporting events).

If someone is using e.g. anabolic steroids or other performance-enhancing drugs, then that should be tested for and factored into their PHRF number. This would greatly reduce the appeal of drugging, as the advantage it lends would be “handicapped out.”

In sailboat racing, we often separate boats into “divisions” whose PHRF numbers are similar enough that they should be able to finish the course within a reasonably commensurate time. Boats in one division all start together. This adds to the excitement and fun, as the boats in each division usually stay within sight of one another, pass and repass each other during the race, and approach the finish line in a pack.

We could likewise have general “divisions” in human-powered sports, in which people of roughly equal PHRF rating all run in the same race. What we would let go of — and about time too imnsho — is the assumption that all “women” are evenly matched with all other “women,” and all “men” are evenly matched with all other “men.” We would simply have human beings competing against fellow human beings who are of similar enough innate capability to make the competition fair and visually dramatic. Final results, as in regattas, would be announced post-race by the handicap adjusters.

If we “equalised” athletes based on their actual physical capabilities, rather than what gender is printed on their passport, we could solve two problems at once. We could stop imposing arbitrary bans on genetic outliers (women with high testosterone, trans women, AIS women); and we could make sure that people born with certain physical advantages do not automatically win every race just because of their lucky DNA. Winning would become a matter of beating the odds and your personal best.

Winning would become what it really should be — as it is in mixed sailboat racing — a measure of focus, determination, practise, expertise, grace, style and grit. Not a measure of how expensive a boat you can afford… or how much testosterone you were — or were not — born with.

We could eliminate all complaints about certain ethnicities or genders having “unfair advantages,” by simply making the competition more fair and the playing field more level.

It seems like an obvious solution. No two humans have exactly the same physical capacities. There is no such thing as a “class race” for humans. And there are far more flavours of human than just two divisions. PHRF for human powered sports would acknowledge this reality. And we could stop using “unfairness” as a stalking horse for prejudice against trans people in sports.