Gregory Brown is a Professor of Exercise Science who recently submitted an expert report on the impact of biological males, such as transgender women, in female sports. Some differences are obviously simply by looking at elite male athletes, who have significantly more musculature, are taller, and have stronger and larger skeletons than women. Others are less obvious, such as the wider hip structure of women, great oxygen carrying capacity of the blood in women. Depending on the type of sport, men have a 10% to 30% advantage over women. As women’s sports have become better funded, leading to equitable training between men and women, the significant differences between men and women have stabilized. Transgender women in female sports will destroy the motivation of women to participate in sports, knowing that at any time a second rate male athlete can simply declare that they feel like a woman, and win races. Greg Brown and David also discuss how the evidence is mounting that even lengthy hormone treatments does very little to erase the biological advantage that males build up through puberty.