Apr 29, 2025 03:29 PM
https://www.eurekalert.org/news-releases/1081633
EXCERPT: . . . Strength, power, speed, and endurance are typically between 10% and 30% greater in males compared to females. However, recent work suggests a shrinking reduction in the performance gap between the sexes as the distance and/or duration increases. Here we address this important issue in our recent study in Frontiers in Physiology.
Using the doubly labeled water method, we reported lower total energy expenditure relative to load carriage in women compared to men during the Alaska Mountain Wilderness Ski Classic – a remote and unsupported 200km Arctic winter expedition . These findings indicate greater metabolic efficiency in women under such extreme conditions.
Sex-specific physiological differences in athletic performance are largely determined by variations in sex chromosomes and hormones. Testosterone levels increase approximately 30-fold in males during puberty and are closely linked to increased muscle mass and strength. In contrast, testosterone levels remain relatively low throughout the lifespan of females.
The menstrual cycle is marked by fluctuations in estrogen and progesterone in females, but these hormones stay relatively constant in males. Elevations in estrogen during the follicular phase have been posited to enhance fat oxidation. However, a recent meta-analysis concluded that variations in estrogen have a minimal impact on metabolism.
So what about ultramarathons and even more extreme events? Pamela Reed and Hiroko Okiyama outperformed their male counterparts in the Badwater and Deutschlandlauf ultramarathons, respectively. While these may be isolated cases, the gap in race durations between males and females has decreased by approximately 3% in events lasting six, 72, 144, and 240 hours over the past four decades. When males and females compete in similar numbers, the gap decreases even further. Fewer elite females participate in ultras compared to elite males.
In studying physiological resilience in athletes participating in the Yukon Arctic Ultra (YAU), the longest and coldest ultramarathon in the world, we observed while working alongside Dr Mathias Steinach (affiliated with the Center for Space Medicine, Berlin)that not a single participant with a body mass index (BMI) of 22 kg/m2 has ever completed the event In fact, the average BMI for this event is approximately 24 kg/m2 for both males and females, with fat mass being 30% higher in females. Despite males having greater amounts of lean tissue mass and less fat mass compared to females, the number of finishers in both sexes is essentially equivalent.
Recent studies have described an ‘Arctic shift’ in females, indicating the activation of cold-induced thermogenesis at a lower temperature compared to males, and potentially reducing metabolic demands under cold stress. Leveraging plasma, serum, stool, hair, muscle and adipose tissue samples from the YAU cohort, future studies will explore the mechanisms responsible for similar levels of resilience despite differences in lean tissue.
Females in combat-forward military scenarios. As a surrogate model for military operations, we measured rates of total energy expenditure (TEE) during backcountry hunting expeditions in Alaska. Hunters, who also volunteer as research participants, are dropped off via bush plane in the wilderness with a backpack, a rifle, and a satellite phone for between two and four weeks. Females typically carry more weight relative to body weight than males, but are no less capable or resilient.
Although the number of participants was small, TEE/lean tissue mass was similar in both males and females, indicating no difference in energy expenditure dedicated to physical exertion. Utilizing new stable isotope methods developed with our collaborators at the University of California Berkeley, we are now studying sex-specific alterations in the structural integrity, cellular respiration and contractile function of skeletal muscle in this cohort.
Although men have historically dominated protective roles in society, emerging data from endurance events conducted in extreme environments suggest that women may be equally, if not more, metabolically resilient under physical and nutritional stress.
We think that one of the coolest (pun intended) aspects of being scientists is that we continually challenge dogma to find new answers to old problems. Perhaps the best-selling author John Gray was right with one minor correction: women may be from Mars (colder), and men may be from Venus (warmer). (MORE - missing details, no ads)
EXCERPT: . . . Strength, power, speed, and endurance are typically between 10% and 30% greater in males compared to females. However, recent work suggests a shrinking reduction in the performance gap between the sexes as the distance and/or duration increases. Here we address this important issue in our recent study in Frontiers in Physiology.
Using the doubly labeled water method, we reported lower total energy expenditure relative to load carriage in women compared to men during the Alaska Mountain Wilderness Ski Classic – a remote and unsupported 200km Arctic winter expedition . These findings indicate greater metabolic efficiency in women under such extreme conditions.
Sex-specific physiological differences in athletic performance are largely determined by variations in sex chromosomes and hormones. Testosterone levels increase approximately 30-fold in males during puberty and are closely linked to increased muscle mass and strength. In contrast, testosterone levels remain relatively low throughout the lifespan of females.
The menstrual cycle is marked by fluctuations in estrogen and progesterone in females, but these hormones stay relatively constant in males. Elevations in estrogen during the follicular phase have been posited to enhance fat oxidation. However, a recent meta-analysis concluded that variations in estrogen have a minimal impact on metabolism.
So what about ultramarathons and even more extreme events? Pamela Reed and Hiroko Okiyama outperformed their male counterparts in the Badwater and Deutschlandlauf ultramarathons, respectively. While these may be isolated cases, the gap in race durations between males and females has decreased by approximately 3% in events lasting six, 72, 144, and 240 hours over the past four decades. When males and females compete in similar numbers, the gap decreases even further. Fewer elite females participate in ultras compared to elite males.
In studying physiological resilience in athletes participating in the Yukon Arctic Ultra (YAU), the longest and coldest ultramarathon in the world, we observed while working alongside Dr Mathias Steinach (affiliated with the Center for Space Medicine, Berlin)that not a single participant with a body mass index (BMI) of 22 kg/m2 has ever completed the event In fact, the average BMI for this event is approximately 24 kg/m2 for both males and females, with fat mass being 30% higher in females. Despite males having greater amounts of lean tissue mass and less fat mass compared to females, the number of finishers in both sexes is essentially equivalent.
Recent studies have described an ‘Arctic shift’ in females, indicating the activation of cold-induced thermogenesis at a lower temperature compared to males, and potentially reducing metabolic demands under cold stress. Leveraging plasma, serum, stool, hair, muscle and adipose tissue samples from the YAU cohort, future studies will explore the mechanisms responsible for similar levels of resilience despite differences in lean tissue.
Females in combat-forward military scenarios. As a surrogate model for military operations, we measured rates of total energy expenditure (TEE) during backcountry hunting expeditions in Alaska. Hunters, who also volunteer as research participants, are dropped off via bush plane in the wilderness with a backpack, a rifle, and a satellite phone for between two and four weeks. Females typically carry more weight relative to body weight than males, but are no less capable or resilient.
Although the number of participants was small, TEE/lean tissue mass was similar in both males and females, indicating no difference in energy expenditure dedicated to physical exertion. Utilizing new stable isotope methods developed with our collaborators at the University of California Berkeley, we are now studying sex-specific alterations in the structural integrity, cellular respiration and contractile function of skeletal muscle in this cohort.
Although men have historically dominated protective roles in society, emerging data from endurance events conducted in extreme environments suggest that women may be equally, if not more, metabolically resilient under physical and nutritional stress.
We think that one of the coolest (pun intended) aspects of being scientists is that we continually challenge dogma to find new answers to old problems. Perhaps the best-selling author John Gray was right with one minor correction: women may be from Mars (colder), and men may be from Venus (warmer). (MORE - missing details, no ads)