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Supreme Court of the United States

New Expert Report Confirms Women Need a Level Playing Field

By Natalie Allen posted on:
January 26, 2022

The recent story about University of Pennsylvania swimmer Lia Thomas has continued to fuel the debate about fair competition in women’s sports. On November 20, Thomas—a male identifying as a female—shattered records in two swimming events, the women’s 200-meter and 500-meter freestyle.

Unfortunately, the Lia Thomas story is not unique. Female athletes across the country continue to face situations where they are forced to compete against male athletes without a fair chance of success. This is due in large part to athletic associations’ polices that allow males to compete against women and girls.

However, a new and detailed export report from Dr. Gregory Brown, a professor of exercise science at the University of Nebraska, refutes the faulty and outdated science behind these athletic associations’ policies. The report summarizes multiple studies around the world that demonstrate the physical advantages males enjoy in athletic competition. Additionally, these studies challenge the misconceptions that male physical advantages only exist after puberty and can be eliminated by testosterone suppression.

Here are some important findings from Dr. Brown’s report:

1) Inherent physiological differences between men and women result in athletic advantages for males.

Similarly gifted and trained males have physical advantages over females—from greater height and weight and larger, longer, and stronger bones to larger muscles and higher rates of metabolizing and releasing energy. These innate physiological traits result in greater muscle strength; stronger throwing, hitting, and kicking; higher jumping; and faster running speeds for males, all of which create an athletic edge over female athletes.

For example, despite greater body weight, males have a roughly 15-20% jumping advantage over women. When examining the vertical jump needed in volleyball, one study found that on average male players jumped 50% higher during an “attack” at the net than female players.

2) Male athletic advantages exist even before puberty.

Most of us tend to attribute male physiological advantages to the developmental changes caused by male puberty. But while boys’ physiological and performance advantages accelerate rapidly from the onset of puberty, data shows that significant male athletic performance advantages exist before puberty begins.

In his report, Dr. Brown points to a European study that examined the athletic performances of boys and girls of elementary school age. The study found that even at age 6, boys have significant advantages in cardiovascular endurance, muscular strength, muscular endurance, speed, agility, and power tests.

In the study, the boys outperformed girls at every age in measures of handgrip strength, long standing jump, 200-meter shuttle run, and predicted VO2 max. VO2 max refers to maximal oxygen consumption, which accounts for 30-40% of success in endurance sports.

3) Male athletic advantages exist even after testosterone suppression

Many athletic associations have relied on testosterone suppression in males identifying as females in an attempt to level the playing field. However, evidence shows that suppression of testosterone in a male after puberty does not substantially eliminate the male athletic advantage. In fact, studies find that males retain a strong performance advantage even after lengthy testosterone suppression. These advantages exist in arm strength, leg strength, running speed, muscle mass, and skeletal configuration.

For example, multiple studies have found that muscle mass only decreases modestly or not at all during testosterone suppression. On average, there is around a 5% loss of muscle mass and strength, but that cannot reverse the 40-50% difference that typically exists between men and women. And even after two full years of testosterone suppression, males still run 12% faster than women. On the track, 12% is an unbeatable margin.

Scientific research continues to point to the necessity of policies that protect women’s athletic opportunities by ensuring girls and women are not forced to compete against men.

Dr. Brown’s report makes scientifically clear that which common sense tells us: when gender identity trumps biology, women’s athletic opportunities will cease to meaningfully exist.

You can view Dr. Brown’s full report here.

Click below to learn more about how ADF is advocating for policies that protect fairness in women’s sports and how you can get involved.

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Natalie Allen

Natalie Allen

Legislative Communications & Initiatives Coordinator

Natalie worked as a lobbyist at the Family Foundation of Virginia and a grassroots associate at Heritage Action for America before joining the Alliance Defending Freedom team.


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