It brings to a sad end a humiliating process in which South Africa’s golden girl appeared in a Swiss court to defend her natural, God-given body.
Testosterone is a hormone that increases muscle mass, strength and haemoglobin - which affects endurance and strength.
Under the new IAAF rules - which strangely apply only to women’s events between 400m to 1500m - athletes classed as having DSDs (Differences of Sexual Development) must reduce their blood testosterone level to below 5 nanomoles per litre of blood.
So what does the ruling mean:
Well, the double Olympic champion will now be forced to take the testosterone-lowering medication for six months before competing.
Yes, you heard right. Caster will be forced to take part in doping!
And not just her, but probably many of her rivals in the 800m and 1500m track events, too.
Hopefully, non-African women will be tested too.
But why stop at women and their muscle mass?
Let’s face it, many star athletes have physical advantages that give them a competitive edge, like bone structure and lung capacity.
Experts argue that barring certain women from competition due to naturally high testosterone levels would be like excluding basketball players because they are too tall.
Can we expect IAAF regulations governing bone structure, too?
Scientists also say that achieving excellence in sport takes a combination of training, commitment, as well as genetics, and that excluding athletes from competition over a single genetic factor has no scientific basis.
Caster has 30 days to appeal the ruling, and so she should.
She has the backing of about 50 United Nations Human Rights Council members, as well as many vocal sports personalities, inclu- ding tennis great Martina Navratilova.
True champ that she is, Caster responded to the ruling as follows: “For a decade the IAAF has tried to slow me down, but this has actually made me stronger.
“The decision of the CAS will not hold me back.”