More than 40 years have passed since Penny Lee Dean set a remarkable record for swimming the English Channel in 1978. Her vivid recollections of the intense cold during training highlight the challenges she faced. "Your hands cramp, your legs cramp," Dean recalls, emphasizing that even after open-water swims, warming up took hours. Overcoming the cold was crucial for her success as a record-breaking swimmer. One advantage women may have in this sport is the ability to tolerate extreme cold, thanks to a distribution of body fat that aids temperature regulation. Dean also believes that women have a higher tolerance for discomfort.

Women are showing they can match or outperform men in various competitive events, from sport shooting to ultrarunning. However, the journey toward greater inclusion in sports is complex, with many questions remaining about the role of sex in athletic performance.

Øyvind Sandbakk, a sports science professor at UiT The Arctic University of Norway, has studied performance gaps between elite female and male athletes, which generally plateau at around an 8–12% difference favoring men. However, the gap can be smaller for ultra-endurance swimming and larger in sports requiring substantial upper-body strength.

In ultradistance events, the ability to manage multiple factors like weather and pain becomes crucial. Gender bias can also limit the pool of competitors, with certain sports being stereotypically feminine or masculine. For example, no men are participating in artistic swimming at the Paris Olympics.

Sandbakk emphasizes the difficulty of separating biological and social factors contributing to differences in sports performance, including unequal access to sports opportunities. Women's pacing abilities can be advantageous in long-distance events, where they tend to be more measured with starting speeds. Competitiveness involves not just physiology but also social conditioning and psychology.

According to a 2023 consensus by the American College of Sports Medicine, differences in athletic performance between boys and girls are minimal before puberty, after which the gap widens. While testosterone levels are linked to muscle size, strength, and competitiveness, there is limited research on how testosterone affects women or how estrogen affects men.

In her book *Better Faster Farther: How Running Changed Everything We Know About Women*, journalist Maggie Mertens highlights that averages can obscure the diversity of hormone ranges. She notes that many elite male athletes have relatively low testosterone levels. Even women with hyperandrogenism, whose testosterone levels reach typical male ranges, don't match men's performance levels.

Before her English Channel record, Dean set a new record for the Catalina Channel swim off Los Angeles, California, crossing 32.5 km (20.2 miles) in under seven hours and 16 minutes. Astonished that her record still stands, Dean is a strong advocate of marathon swimming, especially long races. "I think 20 miles (32 km) and above, women can beat men," Dean asserts, attributing this to women's advantage in cold water due to higher body fat for temperature regulation and buoyancy.

Ned Denison, chair of the International Marathon Swimming Hall of Fame, notes that male swimmers' typical tall and lanky physiques help with speed in normal temperatures but may not provide the same cold resistance as women's bodies do. Journalist Mertens adds that body fat is beneficial in endurance races because it serves as a fuel source when glycogen stores deplete.

Compared to swimming, Sandbakk suggests women might have less advantage in other cold-weather ultra-endurance sports due to proper clothing aiding thermoregulation. However, Dean believes the female edge in long-distance open-water swimming lies more in mental fortitude and discomfort tolerance than physical insulation. Her mental training for the English Channel involved mantras like "the colder the water, the better."

In ultrarunning, as distances extend, the performance gap between men and women narrows. A 2020 analysis showed that beyond 195 miles (314 km), women were 0.6% faster. Mixed evidence exists on whether women have higher pain tolerance than men, but at elite sports levels, comparisons are challenging. Some studies suggest women recover faster after exercise, potentially due to lower muscle mass affecting fatigue and greater flexibility reducing stiffness.

Kim Yeji, a top athlete in shooting sports, echoes Dean’s sentiment about the importance of mental strength. Competing in both women's and mixed shooting events at the Paris Olympics, Kim recently set a world record in the women’s 25-meter pistol event. She emphasizes that shooting is "more about the mind and the spirit," with staying calm under pressure being especially beneficial for women.

In the Olympics, men’s 25-meter pistol events involve rapid-fire shooting, demanding more physicality. A study from the 2020 Tokyo Olympics found that men performed better in events with moving targets, while performance was balanced in stationary conditions. Cassio Rippel, ISSF Athletes Committee Chair, explains that men’s muscles typically provide more stamina, while women’s lower body mass and center of gravity allow better equilibrium control. Rifle events are the most balanced between sexes at the Olympics.

Shooting sports have navigated a unique path regarding women’s inclusion. At the 1992 Barcelona Olympics, Chinese shooter Zhang Shan won gold in the mixed-sex skeet shooting event. However, women were barred from participating in the mixed event at the next Olympics, without a women’s-only version offered.

Decisions about which events to hold and under what conditions are complex, affecting men's and women's performances. Mertens notes that there remains public discomfort with co-ed sports.

The Paris Olympics marks the first with equal numbers of male and female athletes, providing an opportunity to assess remaining inclusion gaps. While much about sex and performance remains unsettled, Sandbakk stresses the need for more research involving women. Most sports science knowledge regarding training, physiology, equipment, and clothing is based on male research. Further research could help narrow performance gaps and increase understanding of athletes beyond the gender binary.

Mertens advocates celebrating women’s sports achievements independently of men’s and maintaining some sex-separated competitions. She believes occasional victories of women over men in sports can help us understand performance as a spectrum, embracing more gender diversity.