By Jonny Lupsha, News Writer

A court decision forces female athletes with naturally high testosterone to face difficult decisions, The New York Times reported May 1. The highest international sports court ruled that women with high testosterone levels must either chemically suppress their hormones or compete against men. Learn more about the body’s hormonal system and the strength of muscles.

Female runner Caster Semenya of South Africa has been at the center of the testosterone controversy in sports for a decade, the Times article said. Athletes routinely undergo testing for performance-enhancing drugs. However, after a big win in 2009, Semenya was also subjected to sex tests due to her high testosterone levels. Since then, the case has increasingly been focused on privacy and what to do about naturally occurring hormones within the body that could give some athletes an edge in competition. Hormones and the endocrine system that produces them play many complex roles in the development of the body, as does the biological differences between women and men.

The Rundown on Insulin

Testosterone helps your body make muscles, which is why courts have zeroed in on it regarding athletes like Caster Semenya. Another hormone that plays a role in muscle development—as well as affecting fat and the liver—is insulin. “Insulin’s main function is to regulate blood sugar levels,” said Dr. Michael Ormsbee, Associate Professor in the Department of Nutrition, Food, and Exercise Sciences at Florida State University. “After you eat and your blood sugar begins to rise, the beta cells of your pancreas secrete insulin, which helps take glucose out of your blood and put it into the cells where it can be stored or used as energy.”

Another function that insulin performs is that it can help you build muscle mass. “This is because insulin-stimulated glucose uptake into muscle cells also enhances muscle protein synthesis by increasing the transport of amino acids into your muscles,” Dr. Ormsbee said. However, insulin levels aren’t as explicitly linked to differences in women versus men as testosterone is; so, it’s unlikely to raise as many questions in competitive sports.

How Biological Sex Affects Body Composition

When the bodies of female athletes like Semenya naturally produce higher levels of testosterone than most women, the women find themselves at the mercy of a rare genetic trait and the courts that rule over the sports world. The recent court decision that women like Semenya must chemically suppress their hormones or compete against men invites a look at the muscular differences between the sexes.

“We have known for some time that men naturally have more lean muscle compared to women, while women tend to have more total body fat,” Dr. Ormsbee said. “This is often explained by the location of body fat, and the unique reproductive function needs of women. The higher level of fat and lower level of muscle in women typically means that women have metabolic rates that are about 5 to 10 percent lower than men of the same height and weight because muscle mass is more metabolically active.” With regard to insulin, which also influences muscle mass, Dr. Ormsbee said that men who store more fat around their internal organs tend to be more resistant to insulin than women who store fat around their arms and legs.

If the sports world continues to scrutinize athletes’ natural physiology, insulin and other related body hormones could soon find themselves under the microscope. For now, the issue with testosterone highlights the delicate crossroads of privacy, biological sex, physical anomalies, and fairness of competition at which competitive sports finds itself in the 21st century.

Dr. Michael Ormsbee contributed to this article. Dr. Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his M.S. in Exercise Physiology from South Dakota State University and his Ph.D. in Bioenergetics from East Carolina University.

Image Credit:
Erik van Leeuwen [GFDL (http://www.gnu.org/copyleft/fdl.html)]
Yann Caradec from Paris, France [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)]