Women’s sport is currently trying to cope with new rules that allow male-to-female transsexuals compete as women.  Danish/Australian golfer Mianne Bagger is currently leading the way in Europe, and deserves great credit for her moral courage and determination.  However, some people - even some transsexual women - have severe reservations concerning the new rules. 

Physical differences between Men and Women
For sometime, experts have been saying that women are rapidly closing the performance gap on men in sports, and some studies even optimistically claim that women could overtake them in the future (e.g. "Will Women Soon Outrun Men?" by Brian Whipp and Susan Ward, Nature, 1992).  But the the brutal reality is most men are still taller, heavier, faster, stronger, bigger, and more powerful than most women, and are likely to remain so.  A controversial but perhaps realistic study by Seiler and Sailer published in Sportscience News found a male-female performance difference of 11 per cent in the 1980s - and 12 per cent today. 

Upon investigation, the list of physical differences between men and women is substantial, even if we only consider factors directly related to sports.

Males typically have greater bone strength and density, greater muscle bulk and broadness in the shoulder area, and greater subcutaneous fat in the upper half of the body.  At maturity, females are generally shorter in height, have more flexibility in their joints, have more delicate ligaments and tendons, have more subcutaneous fat in the hips and lower body regions, have less erythrocyte and haemoglobin mass (which directly affects the ability to of the blood to carry oxygen and get rid of carbon dioxide), and exhibit a greater degree of pelvic tilt and obliquity.  The female elbow offers a greater carrying angle and tendency toward cubitus valgus (i.e. the lower arms stick out more), and the female has smaller lungs, heart, liver, and kidneys than the male.  Female joints are more subject to injury in sports requiring an expulsive effort, sudden stopping, sudden checking of speed and turns, and landing in jumps.  These differences are partly to the man's X chromosome, and partly due to the fact from about age 13 the bodies of boys are powerfully influenced and "masculinised" by a flood of testosterone from their gonads, while simultaneously the growth of girls is actually limited and "feminised" in a more delicate direction by the flood of oestrogen's from their ovaries.

According to one US Army manual:

• The average 18-year-old man is 70.2 inches tall, the average woman of the same age is 64.4 inches tall - a difference of 9%.
• The average 18-year-old man weighs 144.8 pounds, the average woman of the same age weighs 126.6 pounds - a difference of 14%.
• The difference in physical size affects the absolute amount of physical work that can be performed by men and women.
• Men have 50 percent greater total muscle mass, based on weight, than do women.
• A woman who is the same size as her male counterpart is generally only 80 percent as strong. Therefore, men usually have an advantage in strength, speed, and power over women.
• Women carry about 10% points more body fat than do men of the same age.
• Because the centre of gravity is lower in women than in men, women must overcome more resistance in activities that require movement of the lower body.
• Women have less bone mass than men, but their pelvic structure is wider. This difference gives men an advantage in running efficiency.
• The average woman's heart is 25 percent smaller than the average man's.
• For any given work rate, most women will become fatigued sooner than men.
• The lung capacity of men is 25 to 30 percent greater than that of women. This gives men an advantage in the processing of oxygen and in doing aerobic work such as running.

What the Army study does not really emphasise directly is the fact that the "typical" young untrained male has an absolute oxygen intake (termed VO₂ max) of 3.5 litres/min, while the typical same-age female has about 2 litres/min - a 43% difference which translates in to reduced performance and increased fatigue.  The difference reduces to 15 to 20% when the difference in body weight is allowed for, but is not eliminated. 

Part of the reason for the V02max difference is that the male sex hormone testosterone promotes the production of haemoglobin, an oxygen-carrying protein found inside red blood cells, and testosterone also increases the concentration of red cells in the blood.  The female hormone oestrogen has no such effect.  As a result, each litre of male blood contains about 150-160 grams of haemoglobin, compared to only 130-140 grams for females.  The bottom line is that each 'male' litre of blood can carry about 11% more oxygen than a similar quantity of female blood.

If we compare average body fat in males and females, we find the other part of the answer. Young untrained women average about 25% body fat compared to 15% in young men.  If we factor out body composition differences by dividing VO₂ by lean body mass (bodyweight minus estimated fat weight) the difference in maximal O₂ consumption decreases to perhaps 7-10% - close enough to 11% difference in blood carrying capacity just calculated.  But this is a theoretical paper exercise as a female athlete cannot reduce her body fat down to the sub 7% levels often observed in elite males without severe consequences to her health that would soon rule her out of competition anyway.

The Era of Sex Testing
A man competing as woman in many sports would have an unfair advantage for the reasons described.   Perhaps ever since competitive sports began there has been suspicions and rumours that some female competitors were not actually women.

Several earlier examples can be quoted such as the Polish sprinter Stanisllawa Walasiewicz (later Stella Walsh), winner of the 100-meters at the 1932 Olympics (the IOC recovered her medals after learning that she had male reproductive organs), and the German high jumper Dora Ratjen (actually Hermann Ratjen) who came fourth in the 1936 games.  The IOC was worried to learn that three other track-and-field champions who competed as females in the pre-World-War-II games eventually underwent reconstructive surgery to remove external, male-like reproductive structures.

As sport became increasingly super-power politics by other means, the masculine physique, deep voices and five o'clock shadow of some formidable Eastern bloc female competitors was simply impossible to ignore, and sex tests were introduced after the 1964 Olympic games.

Sex testing officially began at the 1966 European Athletics Championships in Budapest.  Women competitors were required to disrobe so that medical staff could determine from their genitals whether they were indeed women.  Of course, many women found this offensive, but it was also noticeable that several dozen "female" competitors immediately faded from the scene such as the suspiciously masculine Press sisters Tamara and Irina from the Soviet Union who between them won five Olympic titles in the shot-put and hurdles respectively in the early 1960's.

However by 1966, sex reassignment surgery had already advanced to stage where “former men” could easily pass this type of "peak and poke" visual test as a woman, therefore at the 1968 Olympics the far more sophisticated polymerase chain reaction (PCR) buccal smear test was introduced to examine the chromosomal picture - if you didn't have XX chromosomes then you couldn't compete as a woman.  Ewa Klubukowska, a 1964 sprint bronze medalist for Poland, had the dubious honour of being the first woman to fail the sex test on account of possessing an XXY chromosome pattern, although she was clearly female in every other way.  "I know what I am and how I feel" she said at the time.  After failing her "female" sex test, Ewa made it a bad joke by getting pregnant and having a baby the next year, although on the side of the coin Austrian skier Erika Schinegger (Women's World Downhill Champion in 1966) became Erik after failing her sex test and later fathered a daughter.  Ewa and Erika were in crowded company at the time, as many other female athletes, including 5 British, failed the new test in its early days. 

From the start the fairness of this gender verification test was hotly disputed, the vast majority of the women affected suffered from Complete AIS and are legally regarded (and regard themselves) as women.  Things came to head in 1985 when the 24-year old Spanish hurdler Maria Jose Martinez Patino failed a female sex test because of her AIS before the 1985 World University Games in Kobe, Japan.  On the way to her first race, she was told that she should fake an injury and withdraw - and if she didn’t, her story would be leaked to the press.  She didn’t back down and she won her race, collapsing with physical and mental exhaustion after the finish line.  The next day, her story was front page news.  She returned to Spain to be stripped of her titles and lose her university scholarship and her boyfriend.  “I knew I was a woman in the eyes of medicine, God, and, most of all, in my own eyes,” Patino told a reporter.  “If I hadn’t been an athlete, my femininity would never have been questioned".  Similarly in the 1988 Olympics an unnamed top women's tennis player was prevented from competing when her condition was similarly identified.  In the 1992 Barcelona Olympics no less than 5 out of 2,406 women tested as "male", all with some form of AIS.  In the 1996 Atlanta games 8 women out of 3387 didn't pass as female - 4 with CAIS and 3 with PAIS.  

Between 1972 and 1984, thirteen women "failed" the Olympics' chromosome test and were barred from competing.  Between 1972 and 1990, one in every 504 elite female athletes was found ineligible as a result of sex chromatin testing yet not one was found to be a "normal male".   In the 1992 Barcelona Olympics, 5 out of 2,406 women tested as "male", all with some form of AIS.  In the 1996 Atlanta games 8 women out of 3387 didn't pass as female - 4 with CAIS and 3 with PAIS, but all 8 were allowed to compete after discussion.  

By now the whole process of sex test was becoming far more of a hot potato than it was worth as blatant cheats (i.e. a man trying to compete as a woman) which were the real target could be easily picked up by other means, for example when giving a routine anti-doping urine sample which had to be visually observed by an official.  Mandatory sex testing for women was finally abandoned for the 2000 Sydney Olympics, but unfortunately considerable publicity was still given by the media to two Brazilian women - Judo competitor Edinanci Silva and volleyballer Erika Coimbra - when it was leaked by someone to the press that both were born hermaphrodites, with non-functioning male genitalia which had been surgically removed.

In February 2004 an  IOC advisory group recommended that individuals undergoing sex reassignment after puberty could compete in the Olympics, but only under certain conditions:

• Surgical changes must have been completed, including external genitalia changes and removal of gonads.
• Legal recognition of their assigned sex must have been conferred by appropriate official authorities.
• Hormone therapy -- for the assigned sex -- must have been given for long enough to minimize any gender-related advantages in sport competitions, a period that must be at least two years after gonadectomy.

On Monday, 17 May 17 2004 transsexuals were formally cleared to compete in the Olympics by the IOC Executive Board.  IOC spokeswoman Giselle Davies said the situation of transsexuals competing in high-level sports was "rare but becoming more common."  IOC medical director Patrick Schamasch said no specific sports had been singled out by the ruling.  "Any sport may be touched by this problem," he said. "Until now, we didn't have any rules or regulations. We needed to establish some sort of policy."

The decision, which covered both male-to-female and female-to-male cases, went into effect starting with the Athens Olympics in August 2004.    The new rules allow the classification as female of men who underwent the SRS operation before or after their puberty.

Do Female Transsexuals have an Advantage?
There are some valid concerns about the physical advantages that male-to-female transsexuals would have competing against women, particular.

Testosterone levels and muscle mass drop considerably after pro-longed hormone therapy and sex-change surgery but the question remains about how much residual advantage the MTF transwoman trains due to her genetic maleness remains and for how long? And although hormone treatments for transgendered athletes certainly diminishes certain differences, skeletal advantages - and possibly lung and heart capacities - are left unchanged.  That could give transsexuals, particularly those having SRS after puberty, with a huge advantage competitive in some sports when even a 1% difference can be the difference between first place and eighth.

The table above is rather speculative, but is supported by the limited research available.  For example one study found that androgen deprivation in MTF transsexuals increases the overlap in muscle mass with women but does not reverse it.

It has been suggested that transsexual women who have SRS after puberty are actually at a disadvantage in sports compared with other women as they are lugging around the large and heavy skeleton of a man without the compensations such as big muscles.  Alison Carlson:- "A man who's castrated and takes oestrogen therapy loses a lot of strength advantages.  With someone like Renee Richards [see below], she didn't suddenly become this winning player on the women's circuit. In fact, she didn't do that well, because although she was tall, she actually had female musculature being carried around on a large male skeleton.  It weakened her."  Personally I'm not quite sure that the overall balance and weighting of advantages and disadvantages agree with this view - although it does depend on the sport.

Complete AIS is sometimes presented as the ultimate form of male-to-female transsexual - the suffer is genetically male XY but has a completely normal female body (albeit lacking internal reproductive structures) due to the total inability of their bodies to use the male androgen hormones produced by their testes in anyway, including for muscle development or VO2max.   But a very interesting paper "Complete Androgen Insensitivity "Syndrome": A Model For Human Performance in Sports". does nothing to support the suggestion that AIS women, or indirectly male to female transsexuals have no advantage in women sports.

The Future
Michelle Dumaresq, is perhaps an early example of the future., Since her sex-reassignment, Michelle claims to have lost bone density, three inches of height [sic], and 30% of her muscle mass along with her testosterone, but nevertheless she became the Canadian women's downhill cycling champ in 2002.   Michelle also mentions receiving e-mails from three transwomen who were about to qualify for the 2004 Olympics. 

There is no doubt that some Olympic events (e.g. running, javelin, pole vault, marshal arts  ..) and many professional, semi-professional  women's sports such as tennis, golf, football (soccer), basketball, bowling, running et al now face a gradual influx of top ranked women who are transsexual, although their transsexuality may not be public.

Looking backwards for more examples of what can happen, we encounter Dr Richard Raskind, an American eye surgeon who underwent SRS at age 40 and changed her name to Renee Richards.  In 1978, at the amazing age of 44 she famously reached the women's quarter-finals of the US Open tennis championship.

Renee (who seems to have some regrets about her own transition and SRS) now sees both sides of the issue regarding whether a transsexual should be allowed to play a women's event, she believes that it comes down to fairness.  Renee would bar transsexuals from women's sports if they were in their 20s and still had muscular male physiques that gave them an advantage over other women:

"That's why we have junior events and senior events, men's events and women's events, and why 130-pound fighters don't fight against 180-pound fighters.  We have categories in sports to have level playing fields.  Tiger Woods or Jimmy Connors or John McEnroe, if they're 25 years old and they have a sex change and within the next five years they go out to play against women, of course they have a great advantage.  Woods probably isn't contemplating any changes, and it's unlikely there will be a rush of men with low handicaps switching sex to clean up on the women's tour.  Bagger may be making history of a sort, but she isn't leading a revolution.  She'll play, she'll be somewhere in the middle, she'll do it for a while, and she's going to get a lot of grief.  She'll get some notoriety. She may like it, she may not like it. And then it'll die down.  It's not going to cause a rash of transsexual golfers.  Those kind of fears are silly."

But Renee has also warned that the decision by the International Olympic Committee means that unscrupulous competitors could use the new ruling to change from men to women to give them more chance of success.

"It's ironic that everyone has tried so hard to keep a level playing field - from corked bats to doping - but now the IOC has come up with a decision that defies fairness in a similar vein.  Sex-reassignment surgery is based on putting materials into your body."

Putting things in a UK context, the new reality is Tim Henman could become Tina Henman and be a [female] Wimbledon champion at last.  With Henman’s strength and speed, height and muscle density, added to his skills, it would be a near certainty even after year of female hormones and aging.

But a counterview to Renee is offered by Kia Siadeski, a transsexual woman whose passion is Barrel-racing - a women only sport.  She says: "I'm 5'5" and weigh 112 pounds - I have no strength advantage, never did.  Not that strength is needed in barrel-racing, anyway - 75% of the sport is about the horse.  But half the women I compete against are bigger and stronger than I am".  But when news of her sex-change got out, she lost her championship.  

Indeed, Renee argues against the theory that desperate athletes will do anything to win the gold, even change their gender. "How hungry for tennis success must you be to have your penis chopped off in pursuit of it?"