Exercise is undoubtedly beneficial for human health, offering a wide range of advantages. One well-documented benefit is improved glucose sensitivity, or ability for tissues to import extracellular glucose for fuel. However, not everyone experiences this adaptation to exercise. A subset of individuals, often referred to as “exercise non-responders,” show little to no improvement in glucose sensitivity despite regular exercise. The reasons behind this lack of adaptation remain poorly understood. Recent studies suggest that the gut microbiome may play a role in mediating this response to exercise. Yet, the microbial signatures associated with enhanced or impaired glucose sensitivity are inconsistent and remain unclear. Additionally, the specific signals produced by the microbiome that drive these effects are not well defined. Gaining a deeper understanding of the mechanisms underlying this phenomenon, as well as the host responses triggered by microbial changes, could open new paths for therapeutic strategies. Using gnotobiotic mouse models and defined microbial communities, we will examine how exercise shapes community composition and identify microbially derived metabolites induced by exercise. Together these experiments will shed light on the molecular underpinnings of the role the microbiome plays in host adaptation to exercise,

The Eating Disorders Program at Stanford Medicine Children’s Health has been providing interdisciplinary medical, psychiatric and nutritional care for adolescents and young adults with eating disorders since 1978. Our inpatient unit and outpatient clinic have treated many female athletes who have experienced serious medical complications from malnutrition, whether it’s been related to lack of awareness regarding the high energy needs of their sport or to intentional food restriction and/or overexercise. Bradycardia, hypotension, orthostasis, greater susceptibility to sports injuries, and hypothalamic-pituitary-ovarian (HPO) axis suppression resulting in menstrual irregularities/amenorrhea, height stunting and low bone mineral density, can all occur in female athletes with inadequate energy intake.

We seek collaborations to raise awareness regarding the medical complications of inadequate energy intake in female athletes. This includes:

• Encouraging routine screening of weight, vital signs and menstrual status by sports medicine providers, physical therapists, and other performance and health staff.
• Increased implementation of screening tools for REDs and eating disorders in athletes.
• Appropriate evaluation and treatment for athletes with amenorrhea.
• Awareness of services available and appropriate referrals for female athletes exhibiting signs of medical compromise from energy imbalance.

Research gaps remain regarding appropriate management of female athletes recovering from medical instability related to overexercise/malnutrition, including:

• How to differentiate RED-S from an eating disorder.
• Acceptable heart rate minimum.
• How and when to reintroduce exercise without leading to vital sign instability or ongoing HPO axis suppression, while maintaining adequate intake for weight restoration.

Bone stress injuries (BSI) are overuse injuries that commonly occur in athletes due to an accumulation of microdamage associated with repetitive stress1. In this exploratory work, we deploy iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) methods.

Thirteen patients with suspected tibial BSI were recruited for scanning at baseline, 6 weeks, and 12 weeks.The imaging protocol included a 2D STIR Fast-Spin-Echo scan in the axial and coronal plane and an axial 3D IDEAL IQ scan. The tibial bone marrow was automatically segmented from the fat IDEAL images. Mean edema fraction, defined as the water proton signal divided by the total (water and fat) proton signal, was calculated for each slice. Maximum slice-averaged edema fraction (EF) was determined for the BSI limb. For intrasubject reference and to study potential bilateral BSI effects, the EF in the contralateral limb was recorded at the same slice as the BSI. EF and edema size were compared between the injured and contralateral legs, across timepoints, and with BSI grade.

In patients with a BSI who completed all visits, EF decreased from baseline scan to 12-weeks (Figures 1). Patients with a grade ≥ 2 BSI had larger EF and edema size in the injured leg when compared to the contralateral leg. Most patients with grade ≥ 2 BSI showed larger EF (11.6-64.8% vs. 5.6-16.1%) and edema size (12-491 voxels vs. 0-38 voxels) when compared to patients with grade 1 or no BSI. However, the ranges within grade 2 and 3 were large and overlapped.

Quantitative evaluation may offer a more standardized and robust method to characterize patients and changes over time. The difference in maximum EF and size values between the injured and contralateral leg, and the large range of values observed within grades, indicate that this could be a useful quantitative measure to improve BSI severity grading during diagnosis.

Sex differences in anterior cruciate ligament (ACL) injury and osteoarthritis (OA) risk remain incompletely understood. This study examined whether structural and mechanical interrelationships differ by sex two years after ACL reconstruction (ACLR). We hypothesized that (1) bone shape differs between sexes and (2) more OA-like femoral shape associates with lower KFM.

Fifty-five participants (31 females, 24 males) completed 2-year follow-up assessments including Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, bilateral MRI, and gait analysis. Femoral bone shape was quantified from 3-T MRI using active appearance models to generate OA-related “B-scores.” Peak KFM during early stance was derived via inverse dynamics. Linear mixed models assessed effects of sex, side, and interlimb differences; correlations with KOOS were explored.

Results showed females had lower height, body mass, and greater valgus alignment (p≤0.004) but similar KOOS and activity levels as males. ACLR knees of males displayed higher B-scores than contralateral knees (p<0.001) and than female ACLR knees (p=0.002). Interlimb B-score differences were greater in males (p<0.001). Associations between femur B-score and KFM were opposite by sex: higher B-scores related to lower KFM in females (–0.23, p=0.001) but to higher KFM in males (+0.25, p=0.016). Higher KFM correlated with better KOOS-Symptoms overall (r=0.344, p=0.030), driven by females (r=0.483, p=0.018).

Despite similar reported outcomes, males showed more OA-like femoral morphology, while females with lower KFM reported more symptoms. Conversely, higher KFM in males related to OA-like shape. These sex-specific associations highlight differing recovery trajectories and support further investigation of loading history and joint health. Leveraging structure-mechanics interrelationships may inform sex-specific strategies for OA risk stratification and post-ACLR rehabilitation.

The data revolution in athletics presents a unique opportunity to enhance performance and protect athlete health. By harnessing large datasets from wearable and lab technologies, our work moves beyond traditional coaching intuition to evidence-based athlete management. Our interdisciplinary approach integrates data from diverse technologies: GPS/LPS wearables for on-field movement analysis, force plates for kinetic profiling, barbell velocity trackers for training load, dynamometers for neuromuscular strength assessment, and timing gates for speed and agility. This creates a holistic, longitudinal performance and health profile for each athlete. We translate this complex data into actionable insights. This allows precise measurement of performance and early detection of decrements indicating fatigue or injury risk. We dynamically optimize training programs to maximize adaptation while mitigating overtraining. Objective, criterion-based return-to-play protocols are structured on data-driven benchmarks. The data also informs athlete grouping for targeted interventions, efficient practice design, and developing personalized acute-recovery protocols. Critically, this work addresses historical data gaps for female athletes by investigating sex-specific factors, like the menstrual cycle’s influence on performance, recovery, and injury vulnerability. Our collaborative model—uniting sports performance coaches, athletic trainers, physical therapists, dietitians and coaches—is central to our scientific innovation. This ensures our work is practically translatable to the field. This framework sets a new standard for athlete care, using large-scale data to unlock new levels of athletic achievement while safeguarding the long-term health and well-being of all of our athletes.

At UC San Diego, we’ve been working to close the gap between research and real-world support for female athletes. As a researcher embedded in Athletics, I act as a bridge between athletes, staff, the lab, and external collaborators. What has worked well in our experience is beginning with relationships. I created a Female Athlete Education Series, meeting with each women’s team to normalize conversations around health, hormones, and performance. We also created the Female Athlete Resource Hub which is our targeted way of servicing our women’s teams. It’s one piece of a broader, coordinated system for holistic health. Being embedded in the weight room in both a support and research role has fostered trust that leads to better questions, more honest conversations, and earlier care for athletes who might have otherwise gone unnoticed. We’ve found that relationship-building is one of the most effective strategies to reduce the barrier to learning about one’s health. This work has also reshaped how we ask research questions and directly contributed to current studies centered on the female athlete. We’re still learning, but one thing is clear: we are doing research for the athlete, not on the athlete. We welcome collaboration and are always open to ideas, insights, and shared experiences.

Athletes often travel for competition, sometimes crossing multiple time zones. While there are notable influences of game time and travel on team win/loss performance, we do not know the physical performance consequences for individuals, especially women. Our work seeks to understand the dimensions of individual performance that may be impacted and to what degree. Healthy, young women (N=48) with a regular menstrual cycle and not taking hormonal contraceptives completed in-lab assessments of muscle strength and functional performance during the day (8 hours after habitual wake time) and night (3 hours before habitual wake time). Muscle strength testing at the knee included isometric concentric-extension (IM) at 30°, 60°, and 90° (3 repetitions @ 5 sec each) and isokinetic flexion/extension concentric/concentric (IK) at 60°/s (5 repetitions) and 180°/s (15 repetitions) as well as drop countermovement jumps and the star excursion balance task (SEBT) measured by OpenCap. Day and nighttime performances were compared using generalized linear mixed effect modeling controlling for dominant leg, menstrual cycle phase, and random participant effects. Performance was generally worse during the nighttime assessment with lower hamstring flexor strength during IK tasks [180°/s task: -1.87 (-3.53 – -0.21) ft-lbs decrease in torque, p<0.05], jump height decreased by 7.5% (p<0.01), and SEBT path length significantly longer in some reach directions (p<0.01). However, not all dimensions of performance were influenced by timing (IM quad, SEBT maximum reach distance). The 60°/s isokinetic task revealed lower strength in the follicular phase at night compared to the luteal phase at night. Our work suggests that some dimensions of performance are more vulnerable to performance timing and could inform smarter preparation for performance after travel across timezones.

Purpose
This study aimed to explore the content and quality of information shared regarding cycle syncing via videos posted on TikTok.

Study Design
Cross-sectional study.

Methods
TikTok was queried on 4/18/2024, using the terms “cycle syncing workout”, “cycle syncing exercise”, “ovulation phase workout”, “luteal phase workouts”, and “follicular phase workout”. For each included video, engagement characteristics, video duration, and posters’ characteristics were collected. The content in each video was assessed across ten categories by two graders. In addition, a modified DISCERN instrument (scored 0-5) and the Global Quality Scale (GQS, scored 1-5) were utilized by two independent experts in women’s sports medicine and physiology to assess the quality of information presented.

Results
A total of 160 videos with a collective 18.9 million views were included. Only 14 (9%) videos were posted by healthcare providers, 7 of these by registered dietitians. Most videos expressed a positive attitude towards cycle syncing (98%). The most popular topics were: logistics of specific workouts (83%), symptoms (39%), logistics of cycle tracking (33%), and body composition (26%). The educational quality of the videos were poor and averaged 0.8±0.5 and 1.8±0.6 on the modified DISCERN and GQS, respectively. Engagement statistics showed weak positive correlations with the modified DISCERN and weak-to-moderate positive correlations with GQS scores.

Conclusion
Our study demonstrated both an overwhelmingly positive attitude towards cycle syncing on TikTok and the low educational value of videos focused on this topic. Healthcare providers should be aware of this trending topic, as well as the growing use of social media for medical education.

Hormone replacement therapy (HRT) may offset some of the musculoskeletal and hormone declines accompanied by the menopausal transition, yet the potential muscular performance benefits remain largely unknown because HRT use has decreased dramatically in recent decades. The aims of this study were to 1) examine trends in HRT use over the past 20 years and 2) determine the relationship between muscle strength, HRT use, and physical activity in middle-aged (40-64) and older (≥65) females. First we identified 19,445 females (≥40y) who completed the National Health and Nutrition Examination Survey (NHANES) between 1999 and 2020 to examine trends in HRT use during this 20-year period. Then we identified 1,083 females (≥40y) from the 2013-2014 cycle who completed a handgrip strength test, and questionnaires on HRT use and physical activity. We used multiple linear regressions to measure associations. HRT use among females decreased by 77% between 1999 and 2011 and remained low to 2020. The greatest drop (47%) occurred between 2001 and 2003. Among older females, a history of HRT use was associated with a 2.1kg strength advantage (p<0.01), and this strength difference widened with age from 2.5% (age 65) to 12.6% (≥80). While grip strength was not associated with total physical activity, increased sedentary activity was associated with weaker grip strength (p<0.001) in older females. Further, HRT appears to moderate this relationship in older females where those who were more sedentary were 8.6% weaker if they had no history of HRT use compared to those who did use HRT. These data suggest that HRT plays a role in maintaining muscle strength, particularly in older females who are not physically active. Such findings indicate the potential muscular benefits of HRT and demonstrate a need for additional research examining the role of HRT in musculoskeletal performance in female athletes across the menopausal transition.

In 2024, Stanford joined the Atlantic Coast Conference (ACC), expanding the average distance of away competition by thousands of miles for a majority of its athletes. We present the case of a competitive female student-athlete who initially presented with severe depression and idiopathic insomnia, and whose symptoms significantly impaired performance and daily functioning. The clinical picture was complicated by regular travel across multiple time zones for competition, further exacerbating mood instability and sleep disruption. The athlete underwent an intensive, multidisciplinary outpatient treatment program that included evidence-based psychotherapy that often occurred twice-a-week due to the patient’s symptom acuity, medication management, sleep hygiene interventions, and coordination of care across medical teams.
Treatment planning carefully accounted for her demanding travel schedule, the unique psychosocial pressures of balancing academics with elite athletics, and the need for longitudinal integrated care. Over the course of treatment, the patient demonstrated marked improvement of depressive and insomnia symptoms as well as increased use of independent and interdependent coping skills outside of sessions. This case highlights the challenges of managing significant psychiatric symptoms in athletes with increasingly complex schedules amid conference realignment and the ‘professionalization’ of collegiate athletics. The case emphasizes the importance of integrated, flexible treatment approaches that address both mental health and performance demands.

The beliefs we hold about our bodies—for example, that our bodies are capable (vs. incapable), our allies (vs. our enemies), or amazing (vs. unremarkable)—have enormous potential to influence our health, performance, and longevity. We report findings from the first attempt to comprehensively identify, define, and measure the beliefs humans can hold about their bodies. Using data from an extensive repository of texts, tens of thousands of tweets, dozens of semi-structured interviews, thousands of survey responses, and multiple large-scale literature reviews, we present an exhaustive list of core body beliefs; propose an inventory to measure those beliefs; and present preliminary data on the distribution of these beliefs in the population. We close with a description of research-in-progress that seeks to leverage body beliefs to lay the foundation for interventions designed to help female athletes achieve their peak potential.