News

Early bedtimes linked to more physical activity the next day

PNAS | June 2025

Most people know that a good night’s sleep can boost their energy for the day ahead. But new research suggests it’s not just how long you sleep that matters, it’s also when you go to bed. In a study of nearly 20,000 people wearing WHOOP biometric devices for a year, Josh Leota, Elise Facer-Childs and their team found that earlier bedtimes from 8pm to 10pm were linked to higher levels of moderate to vigorous physical activity the next day, compared with bedtimes from 11pm to 2am. Their findings suggest that heading to bed earlier could be an overlooked way to encourage people to move more.

Learn more: Monash University, Economic Times, Gizmodo, New York Post, Earth, Tech Explorist, Newsweek

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Intense late-night workouts could disrupt your sleep

Nature Communications | April 2025

High-intensity evening workouts might be hurting your sleep. Josh Leota, Elise Facer-Childs and colleagues analyzed data from over 14,000 people wearing WHOOP biometric devices for a year. They found that exercising within four hours of bedtime pushed sleep later, while workouts ending within six hours of bedtime cut sleep duration. To avoid these sleep disruptions, the team recommends scheduling intense workouts earlier in the day or opting for lighter exercises if you need to train at night. 

Learn More: Wu Tsai Human Performance Alliance news story, Washington Post, New York Post, New Atlas, Gizmodo 

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Higher estradiol levels linked to joint stiffness in female athletes

Journal of Science and Medicine in Sport | June 2025

Female rugby league players have higher stiffness in their ankles, knees, and legs when their estradiol levels rise, a study by Michaela McGrath, Celeste Coltman, and their team reveals. The researchers measured hormone levels and joint stiffness in 24 National Rugby League Indigenous Women’s Academy players across different phases of their menstrual cycles during drop jumps. They found that ankle stiffness was linked to both estradiol and progesterone levels, while knee joint and leg stiffness were correlated to estradiol alone. If confirmed by further research, the results could help coaches better understand and reduce injury risk in female athletes.

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Estrogen-related receptors could help muscles make more energy 

PNAS | May 2025

Estrogen-related receptors (ERRs) play a key role in boosting muscle energy production, especially during exercise. In a mouse study, Weiwei Fan, Ronald Evans and their colleagues found that these receptors not only increase the number of mitochondria – the tiny energy factories inside our cells – but also ramp up their energetic output within muscle cells. When ERRs were removed from mouse muscles, the mitochondria failed to grow or function properly. Developing a drug that targets these receptors might someday help people with metabolic disorders like muscular dystrophy regain their strength. 

Learn more: Salk News Story, GenEngNews, Longevity Technology

Salk Institute

A probiotic may help you breathe easier at high altitudes

iScience | April 2025

Ever wish there was an easier way to avoid feeling sick at high altitudes? Research by James Yu, Tatum Simonsum and team suggests that taking a probiotic could help. Of the 17 men and women in their study who climbed to 3,800 meters, those who took a multi-strain probiotic had higher oxygen saturation levels both day and night and reported fewer symptoms of acute mountain sickness compared to those on a placebo. These findings hint that probiotics could offer a simple, non-invasive way to help people adapt to thin mountain air and feel better at high elevations.

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Skeletal stem cells key to stronger bones, better healing

Cell Stem Cell | May 2025

As we age or healing goes awry, skeletal stem cells switch from building bone to creating scar-like tissue. Thomas Ambrosi, Charles Chan, and their team identified four main subtypes of these stem cells and mapped out where each type lives within bone, revealing how different regions support repair and function. They also discovered two molecules that can push aged or dysfunctional stem cells back into bone-builders, leading to stronger bones in lab dishes and mice. These insights could lead to new treatments that improve recovery from fractures and boost bone health. 

Learn More: Wu Tsai Human Performance Alliance news story

Courtesy of Thomas Ambrosi

Current prediction equations for resting metabolic rate are unreliable for detecting REDs in elite athletes

Human Kinetics Journal | April 2025

Current means for assessing an athlete’s resting metabolic rate aren’t reliable for detecting risk of Relative Energy Deficiency in Sport (REDs), according to a new study of 180 elite athletes. Ida Heikura,Trent Stellingwerff, and team compared resting metabolic rate (RMR) to REDs risk scores using a new assessment tool, but found that RMR measurements failed to consistently identify athletes with REDs. Depending on which of the 11 prediction equations they used, the percentage of athletes classified as having low RMR ranged wildly from 1% to 68%, while the actual prevalence of REDs was 46%. The findings suggest that using RMR is not an effective screening tool for REDs.

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