Introduction
The recent IOC consensus statements emphasize the reciprocal interplay between mental health and low energy availability (LEA). Indeed, psychosocial factors can critically shape behaviors that influence energy availability by impacting energy intake and/or exercise energy expenditure.

Objectives
To identify psychosocial traits associated with increased risk of LEA in active females that can inform proactive safeguarding practices against the potential development of Relative Energy Deficiency in Sport (REDs).

Methods
This cross-sectional study evaluated biopsychosocial features associated with LEA risk using an adapted, scored online screening questionnaire (SS-DEAQ), where a score <0 indicated elevated LEA risk. The questionnaire was disseminated internationally to females engaging in ≥3 hours of exercise per week. Data were collected between February and July 2024.

Results
Of 147 internationally recruited female athletes from varied sports (age: 24 years [22–28]; SS-DEAQ score: 4 [0–7]; 48% Tier 1–2 training/performance calibre), 21% were classified as high-risk for LEA. Compared to their lower-risk peers, high-risk participants placed greater importance on weight and food control in their self-esteem (58% vs. 31%, χ²=7.7, p<0.01; 71% vs. 43%, χ²=7.6, p<0.01), exhibited more characteristics of exercise dependence, and reported significantly higher rates of mental health co-morbidities (35% vs. 2%, χ²=34.6, p<0.001). Attitudes toward carbohydrates did not differ significantly across risk groups.

Conclusion
This study identified distinct psychosocial patterns associated with elevated LEA risk in female exercisers which may provide important insights to enhance safeguarding practices and enable proactive interventions before clinical symptoms emerge.

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.

Despite the well-documented benefits of sport, female athletes face persistent stressors, including injury, low energy availability, body-image pressure, sleep disruption, and cumulative stress, that jeopardize both performance and well-being. Resilience, the ability to adapt and thrive under adversity, is essential for athlete health, yet the field still lacks clarity on the modifiable protective factors that reliably support resilience across diverse athletic populations. Without this knowledge, evidence-based interventions remain limited. This presentation will report findings from one of the largest and most comprehensive longitudinal studies of female athlete resilience to date (N≈500). Using a broad, integrative framework, the study examined predictors of resilience across emotion regulation, experiential avoidance, intolerance of uncertainty, sleep, low energy availability, injury history, contextual body image, excessive training/body disregard, PTSD symptoms, perceived stress, and social support. Results reveal both barriers that undermine resilience and protective factors that promote it, offering novel insights into how adaptive resilience unfolds over time. The work’s innovation lies in both scale and translation. By identifying leverage points for targeted intervention, it moves the field beyond isolated risk factors to actionable strategies. Early applications show the promise of embedding resilience-informed screening within training environments and integrating intervention tools into athlete systems, creating a blueprint for real-world impact. Our team has spent two decades translating complex science into practical tools—developing DOD-funded military programs, athlete-care systems, and NIH-supported initiatives such as the Female Athlete Body Project. From NCAA coaches’ workshops to resilience-informed screening, we have demonstrated that research and practice can merge to deliver scalable, evidence-based solutions. This work provides a clear path to safeguard mental health and sustain peak performance, setting a new standard for resilience programming in female athletes.

Background
Female adolescent athletes in pivoting sports face a disproportionately high risk of anterior cruciate ligament (ACL) injury, with recurrence rates remaining a persistent challenge after reconstruction. Lateral extra-articular tenodesis (LET) is performed during ACL reconstruction to reduce graft failure and rotational laxity. Prior research showed that the Anterolateral Ligament (ALL) and Lateral Collateral Ligament (LCL) origins are close to the distal femoral physis (DFP) with positional variability by age. This study aims to characterize the relationships of the DFP, the ALL and the LCL origins, to guide LET graft placement without causing significant femoral physeal injury.

Methods
Seven pediatric cadaveric knees (aged 8 to 16) were dissected. The iliotibial band (ITB) was resected to reveal the ALL and LCL. Tibial internal rotation was utilized to enhance visualization of the ALL. Metallic pins were placed at the ALL and LCL femoral origins. Sagittal and coronal fluoroscopic images were captured. The distance from each pin to the DFP was measured using coronal images, and AP ALL/LCL positions using sagittal images.

Results
In the coronal view, 6/7 ALL origins, and 7/7 LCL origins were distal to the DFP. The ALL femoral origin was 1.4 +/- 1.01 mm distal to the DFP. The LCL femoral origin was 4.9 +/- 3.18 mm distal to the DFP. In the sagittal view, the ALL origin was posterior to the LCL origin in 5/7 and anterior in 2/7 specimens.

Conclusion
The ALL and LCL origins are close to each other and the DFP, with AP positional variability. LET reconstruction using the ALL femoral origin as a landmark should position the graft at least 1.4mm distal to the DFP and posterior to the LCL origin. These findings support modifying LET tunnel positioning using anatomic and radiographic landmarks to minimize the risk of physeal injury, and optimize ACL/LET reconstruction outcomes to preserve long-term joint health and performance in growing female athletes.

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.

Introduction
Anterior cruciate ligament (ACL) injuries are life-altering and disproportionately impact adolescent female athletes. Current screening methods are expensive, time-consuming, and rely on subjective or kinematic measures, limiting their effectiveness. Rapid estimation of human motion dynamics—the external forces driving movement—could enhance injury prevention screening. This study compares estimates of ground reaction forces from a machine learning model to gold-standard force plate measurements in a cohort of adolescent female athletes performing ACL injury prevention screening tasks.

Methods
We developed DynamicsNet, a physics-informed temporal convolutional network that predicts ground reaction forces from kinematic features. We trained the model on motion capture and force plate data from over 270 individuals and nine activities (Werling 2024). We evaluated its effectiveness for ACL injury prevention screening by testing DynamicsNet on an unseen dataset of video-based kinematics from double-leg drop jumps performed by 26 adolescent female athletes, totaling 74 trials. We computed the mean absolute error between the peak vertical ground reaction force predicted by the model and measured by force plates, as well as during the period of foot-ground contact (i.e., foot strike to push off).

Results
DynamicsNet predicted vertical ground reaction force with a mean absolute error of 0.21 bodyweights (BW) during double-leg drop jump landings (Figure 1). For peak forces, the model was less accurate, with an error of 0.67 BW. In previous research, ACL-injured athletes had 0.3 BW greater peak vertical ground reaction force during drop jump landings than uninjured athletes (Hewett 2005). To capture clinically meaningful kinetic differences and decrease error, future work will fine-tune the model on ACL-specific data. Preliminary analysis suggests DynamicsNet could be adapted for dynamics-based, large-scale screenings to prevent ACL injuries.

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.

Adolescent female athletes are 2-3 times more likely to sustain an Anterior Cruciate Ligament (ACL) injury, and over 70% of ACL injuries are noncontact in nature and likely preventable[1, 2]. Implementing low-cost, real-world assessments to identify risky movement patterns could significantly lower ACL injury rates through targeted training. The ACL Injury Resilience (AIR) Score[3] scores an athlete’s movement patterns (i.e., kinematics) from a set of common injury-risk assessment activities, and can be collected with smartphone-based motion capture tools like OpenCap[4]. However, it is unclear whether the surface on which the assessment is performed affects scoring consistency. We hypothesized that AIR score rankings would be similar across surfaces.

Kinematic data were collected using a 3-phone OpenCap setup for 10 recreational athletes on three surfaces: grass, concrete, and wooden flooring. On each surface, participants completed two trials of five activities: run cuts, single- and double-leg drop jumps, drop cuts, and single-leg squats. Squats were segmented into individual repetitions, and all other activities were segmented from initial contact to the following toe-off event. Point metrics related to injury risk in past prospective studies were extracted from each trial as inputs to the AIR score. The AIR score was computed separately for each surface, and participants’ scores were ranked. We compared AIR scores and rankings using Friedman’s and Kendall’s W tests, respectively.

There were no statistically significant differences between surfaces (p = 0.670), and rankings showed strong agreement (W = 0.906), indicating that AIR score rankings were similar across the three surfaces. Our findings suggest the AIR score can consistently measure the kinematic factors associated with ACL injury risk across common athletic surfaces. The consistent AIR score rankings we observed provide confidence in using OpenCap in-the-wild to measure injury resilience.

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.

Female athletes sustain anterior cruciate ligament (ACL) injuries at disproportionately higher rates than males, in part due to increased dynamic knee valgus (DKV). Hip adduction and internal rotation are key biomechanical contributors to DKV and can serve as practical proxies when direct knee frontal-plane measures are not easily extractable. Scalable technologies to capture these features outside of laboratory environments may improve injury risk screening and monitoring measures.

We evaluated 28 post-operative knee rehabilitation patients using smartphone-based motion capture while they performed standardized two-legged squats. Videos were processed through a validated pose-estimation pipeline to extract hip adduction and internal rotation angles at ~45° of knee flexion, where sex-based differences in DKV are most often reported. Differences between male and female participants were analyzed using Mann–Whitney tests, which are robust to non-normal data and outliers. Feasibility was assessed by capture rate and workflow integration.

Smartphone-based capture was feasible in the clinic with high completion rates and minimal setup burden. Median hip adduction and internal rotation did not significantly differ between sexes, contrary to prior literature. However, several influential outliers may have impacted results. Excluding extreme cases suggested a trend toward higher hip internal rotation among females, aligning with reported patterns of greater DKV risk.

This pilot study demonstrates the feasibility of smartphone-based hip kinematic assessment as a scalable proxy for DKV. Findings should be interpreted with caution given the small sample size and outlier influence. Measurements at 45° may underestimate peak valgus, which often occurs at ~90° of knee flexion. Larger cohorts and validation against laboratory gold standards are needed. Future studies may reveal sex-based differences more consistent with established biomechanical risk profiles.

Napping can reduce fatigue and improve athletic performance, encouraging some athletes to use this short-term strategy before competitions. Whether it is necessary to nap in darkened room to improve performance, however, is unclear. To address this question, we conducted a within-subject, randomized crossover study in a sports stadium with ten elite female athletes (mean age: 21.6 ± 1.5 years). Each participant was asked to nap for 20 minutes on two separate occasions, both conducted at noon on the same day of the week but separated by two weeks. In a randomized order, naps occurred under either a room light (200 lx) or a dim light (5 lx) condition. Pre- and post-tests were administered to evaluate changes before and after the nap and analyzed with mixed effects models.

Dim light nap opportunities had fewer negative effects on sleep quality (p<0.01) and was rated as more acceptable than the room light condition (p<0.01). In both conditions, objective alertness (median reaction time; Psychomotor Vigilance Test, PVT) was lower after napping (p<0.01), suggesting sleep inertia, though the number of PVT lapses, a measure of focus, reduced in the room light condition (p<0.05). Neuromuscular reaction time of the dominant hand on a ruler drop test improved in the dim light condition (p<0.05). No significant effects were observed in lower-limb movement (drop jump test, OpenCap), visual processing speed (critical flicker fusion frequency), heart rate and oxygen saturation (fingertip monitor), or emotional tests (p’s>0.05).

Our findings suggest that napping in a dim light environment benefits female athletes by improving subjective comfort and motor control. If competition lighting cannot be altered, athletes may consider using an eye mask. Furthermore, because a 20-minute nap may induce sleep inertia, we recommend that athletes shorten nap duration or allocate adequate time for recovery after awakening before competition.

Background
Despite advances in strategies for risk reduction and treatment, anterior cruciate ligament (ACL) injury remains a significant challenge to female athlete health and safety.

Purpose
To synthesize evidence across nine meta-analyses examining sex differences in both primary and secondary ACL injury.

Methods
We conducted a series of meta-analyses spanning four decades of published literature in young athletes and patients. Analyses evaluated sex differences in risk of sustaining a primary ACL injury, as well as the influence of sport type and competition level. For secondary injuries, we examined the impact of autograft type and age on graft failure, contralateral ACL injury, and return-to-sport (RTS) rates following ACL reconstruction (ACLR).

Results
Incidence of primary ACL injury in females is 1.7-2.2 times that of males across sports, and risk increased with level of competition (p<0.05). The risk ratio increased to 3.0 for contact sports and 5.5 in high-impact rotational landing sports (eg. gymnastics, etc.), with females at greater risk (p<0.05). Following ACL injury and ACLR, graft type was associated with sex differences in outcomes. Among patients ≤18 years old, females with hamstring tendon (HT) ACLR had a 50% higher risk of autograft failure compared with males (p < 0.05). Additionally, among patients ≤25 years old, females undergoing bone–patellar tendon–bone (BPTB) ACLR had a 20% higher risk of contralateral ACL injury compared with males (p < 0.05).

Conclusion
Female athletes face substantially higher risks of both primary ACL injury and adverse outcomes following reconstruction. Specifically, females exhibit greater vulnerability to graft failure with HT ACLR and to contralateral ACL injury with BPTB ACLR relative to males of a similar age. These findings underscore the continued need for sex-specific advancements in injury risk reduction, rehabilitation, and surgical strategies to improve outcomes and reduce the long-term burden of ACL injuries in female athletes.

Unmet need
How do we prevent primary and secondary ACL injury in female athletes?

The impact of testosterone therapy on hormone cycles, exercise capacity, and physiology of transmasculine individuals is not well understood. Existing studies report limited metrics at large time intervals between data collection. Here, we collect high-resolution temporal data from a single amateur trans male triathlete over a time period of 13 months–including one baseline month and twelve months on testosterone therapy–to characterize hormone, strength, body composition, aerobic, and training load profiles. Daily urine hormone monitoring revealed that progesterone and luteinizing hormone are the clearest metrics to predict cessation of menses. After one year, the participant increased lean body mass by 12%, average hand grip strength by 13%, jump height by 16%, and average knee isometric strength by 15%, but, in contrast with prior research, did not lose fat mass or show changes in isokinetic knee strength. While absolute VO2 max increased by 10%, relative VO2 max (e.g., normalized to body mass) only increased during corresponding peaks in training load. We provide guidelines to monitor trans males during testosterone therapy and recommendations to scale this case study to a larger population.

Background
Patellar instability occurs at a significantly higher rate in young females than males, placing female athletes at increased risk of early recurrent instability and osteoarthritis. In adults, MPFL/MQTFL reconstruction can improve stability and reduce revision surgery risk. However, the native biomechanical properties of the MPFL/MQTFL in pediatric knees is unknown —which is essential for guiding graft selection. This purpose of this study is to characterize the biomechanical role and native strength of the MPFL/MQTFL complex to inform appropriate graft selection in pediatrics.

Methods
7 pediatric cadaveric knees (age 8–16y) underwent dissection. The MPFL/MQTFL complex was isolated and clamped to an MTS machine. Preconditioning was performed (20 cycles, 1–10 N), followed by cyclic loading (500 cycles, 10–30 N), and pulled-to-failure (at 100 mm/min). Displacement, stiffness, and maximum load were recorded. Data was summarized using descriptive statistics. Published adult values for MPFL/MQTFL strength were used for comparison.

Results
The MPFL/MQTFL complex demonstrated a failure load of 166.9 ± 52.9 N. Cyclic elongation at 30 N was 0.9 ± 0.6 mm, and stiffness was 30.9 ± 10.1 N/mm. Failures consistently occurred near the femoral attachment. The observed failure load measurements were comparable to published reported adult values (158.3 ± 76.3 N).

Interpretation
The MPFL/MQTFL complex demonstrated substantial strength in skeletally immature knees. This provides guidance in determining graft strength thresholds in pediatric reconstruction to reduce recurrent instability, especially in females with higher risks of injury.

Conclusion
This study establishes biomechanical data for the native MPFL/MQTFL complex, and supports optimal graft selection and surgical planning to improve surgical outcomes and reduce risk of future injury.

The impact of the menstrual cycle on athletic performance and injury risk is of top concern among female athletes. Some studies have found increased strength, slower muscle recovery, and higher fatiguability mid-cycle, around suspected ovulation, while other studies have found no difference. This variability in data stems from the limitations of menstrual cycle phase identification. Many studies use self-reporting as a method of cycle tracking which can lead to inaccuracies for females with irregular or anovulatory cycles—up to 25% of the female population.

In addition to their roles in the menstrual cycle—the triggering of ovulation by LH and the thickening of the endometrium by estrogen and progesterone—menstrual hormones have studied effects on the musculoskeletal system. Of note is estrogen’s effect on tendon and ligament laxity. This is due to the prevention of cross-linking between collagen molecules, making both tendons and ligaments less stiff and more prone to tearing. More relaxed tendons could lead to reduced power output during estrogen peaks.

The aim of this study is to determine whether muscle fatiguability and recovery vary with the menstrual cycle (Figure 1). LH, estrogen, and progesterone will be monitored periodically using an at-home urine test (Oova, Inc). The progesterone peak will be confirmed using a competition enzyme-linked immunosorbent assay (ELISA) (Eagle Biosciences). Cycle tracking will allow for proper phase identification for study visits, which will take place during the early follicular, ovulatory, and mid-luteal phases. T2 and T2* relaxation will be mapped before and after a wall-sit exercise at each time point to measure muscle activation and acute recovery from exercise. Strength and fatigue will also be measured using a HUMAC-NORM lower limb dynamometer.

Accurate tracking of menstrual cycle hormone fluctuations is the first step to understanding the relationship between menstruation and physical performance.

Background
ACL tears are an increasingly common injury in pediatric female athletes, and the relative risk for females compared to males can be as high as 3.1-4.1 in high-risk sports such as basketball and soccer. Numerous studies have identified ACL anatomic landmarks in adult knees to guide ACL reconstruction surgery, but limited data is available for pediatric ACL landmarks.

Purpose
To describe anatomy of the ACL in pediatric knees with comparison to adult data.

Methods
7 fresh-frozen pediatric cadaveric knees (ages 3-4) were dissected to expose the anteromedial (AM) and posterolateral (PL) bundles of the ACL. The femoral footprints of these bundles were measured, and spatial relationships to the distal femoral physis (DFP) were assessed using fluoroscopy. Measurements of the tibial bundle footprints were also recorded, along with their spatial relationships relative to the anterior medial and lateral meniscal roots. The perpendicular distance from each footprint’s center to the anterior tibia and medial tibial spine were measured.

Results
Both the femoral and tibial footprint areas of the ACL bundles in 3- and 4-year-old knees were approximately 50% of those in adult knees, despite being 25-30% of the age of skeletal maturity. The AM bundle femoral origin was consistently close to the DFP ((8.6±1.8)mm away at the most proximal point). The tibial insertion of the ACL was particularly close to the anterior meniscus roots, with the anterior lateral meniscus root being (4.0±1.6)mm away from the PL bundle.

Conclusion
The proximity of the femoral physis to the ACL origin demonstrates that precise graft placement without significant physeal injury is possible, but the error margin is small. Meanwhile, the small separation between the anterior meniscus horns and the tibial insertion of the ACL highlights the narrow window for safe tibial drilling. Our study may help optimize graft placement to prevent physeal or meniscus root injury.

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.

Background
Female athletes have a higher incidence of knee injuries and greater joint laxity than males, increasing their risk for proximal tibiofibular joint (PTFJ) injury. Although isolated PTFJ injury is rare, it can be disabling for young athletes. Existing anatomical studies have focused on adults and may not be applicable to young female patients due to differences in anatomy and the open physes. This study aims to define the spatial relationships between PTFJ stabilizing structures and the proximal tibial and fibular physes to inform the development of growth plate–sparing surgical procedures specific to the female athlete.

Methods
Two pediatric cadaveric knees from one 8-year-old female specimen were dissected to isolate the anterior and posterior proximal tibiofibular ligaments. Each knee was imaged using a mini-C arm. The insertion sites of the PTFJ on the tibia and fibula were classified relative to the adjacent physis and absolute distances from each insertion site to the nearest physis were measured using ImageJ software. Ligament lengths were also recorded.

Results The mean lengths of the anterior and posterior PTFJ ligaments were 4.1 ± 0.3 mm and 13.6 ± 5.7 mm, respectively. The anterior tibial insertion was seen below the level of the physis (mean distance 9.1 ± 0.8 mm), while the anterior fibular insertion was seen just below and at the level of the physis (1.0 ± 1.3 mm). The posterior tibial insertion varied (absolute distance 4.8 ± 3.1 mm), with attachments below and above the physis, and the posterior fibular insertion was seen below the level of the physis on both knees (2.6 ± 0.1 mm).

Conclusion
This study provides the first detailed anatomical description of the female pediatric PTFJ relative to the growth plate. Insertion sites were in close proximity to the physis. These findings emphasize the need for pediatric-specific surgical approaches that avoid physeal injury when restoring proximal tibiofibular joint stability in female patients.

The principles we apply to performance and injury prevention in elite athletes can apply across the lifespan. Our group treats optimal human performance as a goal throughout the game of life. During perimenopause, there are many external factors that make the game tougher. Fluctuating estrogen levels, changes in body composition, and symptoms add on to already existing barriers to strength training (e.g. requirements for technical knowledge, heavy equipment, time). The increased barriers are combined with an increased need for strength training, as estrogen is involved in muscle recovery and growth. Further, perimenopausal women are not frequently researched due to the variability of symptoms, and the still open question about how the estrogen receptors in the muscles change during this time period. Many researchers worry about finding “signal in the noise.” Finally, most of the current research uses in-person training and requires gym equipment. For generalizability and long-term adherence, it is important to identify the best ways to teach women how to strength train on their own, with the minimal dose for the maximal gain, so they can be athletes throughout their whole lives.

Our Stronger intervention is investigating an at-home, progressive strength training using home-made sandbags as incremental weights, and instructional videos featuring near-peer models and a strength coach. All conditions perform 3 sets of five compound movements twice a week to an effort of only 1 repetition left in the tank. A main condition difference is – one group is doing 2 sessions a week of 5 exercises (each session ~ 28 minutes), while the other group is doing 10 individual “strength snacks” a week (each snack ~ 5-8 minutes).

We’ll discuss initial feedback, preliminary trends, and opportunities for future collaborations.

A growing clinician shortage highlights the need for scalable digital tools to both deliver interventions and remotely measure human performance across ages and abilities. Advances in technology now make it possible to capture these measures remotely in someone’s home, moving assessments out of the clinic and leveraging everyday devices like smartphones to provide richer performance metrics. A key question is whether people, especially older women at high risk for falls, will use these tools effectively. To explore this, we embedded smartphone video assessments into a digital balance intervention, asking participants to record physical performance tests before and after the program. We will share findings from this work, including feasibility, barriers, and opportunities, and discuss how lessons learned can inform the design of scalable digital performance assessments to support female health and performance across age and abilities.

Purpose
To quantify within-subject relationships among countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) variables, characterize their temporal behavior across a competitive season, and examine associations with game performance in women’s basketball.

Methods
18 athletes (21.6 ± 1.9 y) completed CMJ and IMTP testing for 33 weeks. Within-subject (demeaned) Spearman correlation matrices were used to identify functional clusters. Representative CMJ (jump height, peak power, contraction time, RSI(mod) and IMTP (peak force, impulse 100 ms, RFD 50 ms) variables were modeled longitudinally with mixed-effects models. Game outcomes from 24 contests were linked to the nearest prior test and evaluated with Spearman correlations and leave-one-out cross-validated linear models.

Results
CMJ variables clustered into (i) force-production measures (impulses/peak power; moderate–high positive associations), (ii) performance outcomes (jump height with relative power), and (iii) temporal measures (contraction/phase durations). IMTP variables formed tight early-impulse and RFD clusters, with peak-force measures grouping separately. Cross-test associations were generally small (|ρ| ≤ ~0.30), suggesting complementarity. Marginal means showed modest, nonuniform trends—RSI(mod) tended to increase and contraction time to decrease late season, while IMTP peak force exhibited a mid-season rise—amid high within-player variability. For game performance, only CMJ RSI(mod) was positively correlated with point differential (ρ = 0.46, p = 0.024); others were small and non-significant indeed.

Conclusions
CMJ and IMTP capture largely independent neuromuscular qualities and show modest, test-specific seasonal changes. RSI(mod) relates positively to point differential, but single neuromuscular metrics showed limited standalone predictive value, supporting their primary use for readiness monitoring alongside contextual/tactical factors rather than game-to-game prediction.

Understanding of the earliest signs of human health and disease requires fast and robust imaging of the human body. Imaging methods, in particular Magnetic Resonance Imaging (MRI), can create detailed images of various tissues of the body, but they often require long, complex scan and image processing times. The Center for Advanced Imaging in Human Performance, directed by Dr. Garry Gold, was established in 2024 at Stanford University to develop and use the most advanced imaging tools available to optimize and improve human performance in all areas. The goals of the center are to use imaging to discover scientific evidence about human performance, and predict, prevent, and provide evidence of best treatments for injuries. The Center for Advanced Imaging in Human Performance focuses on studying the performance of athletes and people across the age and abilities spectrum, including female athletes. Advanced instruments available for research include multiple MRI machines, including a Positron Emission Tomography (PET-MRI) and 3 tesla (T) and 7T MRIs. Other instrumentation of the center include ultrasound, photon counting CT radiography, and animal imaging resources. Faculty affiliates of the center currently include Feliks Kogan and Akshay Chaudhari, and more faculty from different partners are welcome. The center faculty are available to help optimize use of imaging tools in research studies. The center currently collaborates with sports teams and the Wu Tsai Human Performance Alliance. Examples of ongoing collaboration with the Wu Tsai Human Performance Alliance include using MRI to track muscle recovery of the female athlete and understanding of bone stress injuries, common in female runners. The direction and vision of this center are looking forward to continued progress in precision health and human performance.

Background
The menstrual cycle’s impact on athletic performance is a top concern for female athletes. Previous studies have found increased strength, slower muscle recovery, and higher fatiguability mid-cycle; others found no difference. Quantitative MRI (qMRI), in addition to strength testing, may be more sensitive to changes in muscle function than traditional methods.

Aims
This study aims to determine if muscle strength, acute recovery, and fatiguability change across the menstrual cycle.

Methods
Two naturally menstruating participants completed strength testing and one of those participants completed an MRI session at two different phases of the menstrual cycle. To measure quad strength, participants were asked to press up into the dynamometer at 60° for 5 s. Participants then performed 15 reps of an isokinetic flexion/extension test. The tests determine peak torque and fatigue index: the difference between the torque of the first and last rep of isokinetic contraction. Participants were scanned in a 3T MR scanner before and after a wall-sit exercise at different phases in their cycle, determined through cycle tracking. Difference from peak to baseline T2/T2* signal, 𝚫, is related to muscle activation, and signal decay constant, 𝞽, is related to acute muscle recovery.

Results
Participant 1: Peak torque and fatigue index were higher in the luteal phase compared to the follicular phase (Table 1).

Participant 2: Peak torque was higher and fatigue index was lower at mid-cycle compared to the follicular phase (Table 1). T2/T2* signal decay (𝞽) was longer in the luteal phase compared to the follicular phase (Table 2).

Conclusion
Initial data suggest that changes to muscle function varies during the menstrual cycle. Future experiments will use urine and saliva-based hormone tracking to confirm menstrual cycle phases. A larger cohort will be recruited to further explore how the menstrual cycle affects muscle function in naturally menstruating females.

Background
Functional Popliteal Artery Entrapment Syndrome (fPAES) is a rare cause of exertional leg pain in athletes. We aimed to capture the patient perspective to better understand symptom presentation, recovery, and long-term impact on return to sport, with attention to gender-specific differences.

Methods
We did a statistical chart review of athletes undergoing surgical treatment for fPAES at our institution (2005–2025). Structured interviews or surveys were also conducted (mean 8.3-year follow-up) and thematically analyzed.

Results
During the study period, 125 limbs in 73 athletes underwent surgical debulking; 46% (64 limbs in 36 patients) completed structured interviews. Women comprised 63% of the surgical cohort and 69% of respondents.

Neurological symptoms were reported by 50% of survey participants, but notably, no men reported these symptoms. Reporting neurological symptoms correlated with delayed diagnosis. The presence of neurological symptoms was paradoxically associated with improved odds of full recovery. Disabling symptoms described were most commonly calf pain (89%), neurologic symptoms (50%), calf pain at rest (33%), cold sensation (31%), and swelling (19%).

Male gender was a positive predictor of return to sport: 77.8% of women returned to sport compared with 90.8% of men (OR, 5.16; P = .038). In a Cox proportional hazards model, males also had a significantly lower risk of long-term recurrence compared with females (hazard ratio, 0.08; 95% CI, 0.01–0.62; P = .016).

Conclusion
fPAES disproportionately affects women, who present earlier and more often with neurologic symptoms. Despite longer delays to diagnosis, most women achieved high rates of recovery and return to activity following surgery. Recognition of these gender-specific patterns may improve earlier identification and optimize management in young women athletes presenting with exertional leg pain.

Skeletal muscles of males are stronger than females for elite and non-elite athletes, but the decline with aging is greater in females than males. It is not known if the widening sex difference with age is observed in skeletal muscle fibers that are the foundation of strength. This study determined whether sex differences in fiber cross-sectional area (CSA), fiber type distribution, and proportional area remained after controlling for age (young, 18-34 yrs; middle aged, 35-64 yrs; older ≥65 yrs) and physical activity across various muscles biopsied. Meta-analysis was performed on 6222 participants (Males = 3501; Females = 2721) extracted from 156 studies. Males had larger type I CSA (4936±1250mm2 vs 4151±1074mm2; P<0.001, 16% diff), type II CSA (5272±1950mm2 vs 3483±1309mm2; P<0.001, 34% diff), type II distribution (51.6±14.6% vs 48.3±13.0%; P<0.001), and type II proportional area (55.0±14.4% vs 47.9±13.1%; P<0.001) than females, respectively. Conversely, females had greater type I distribution (51.4±12.1% vs 48.3±13.3%; P=0.01), and type I proportional area (51.8±12.4% vs 44.9±13.2%; P<0.001) than males. The sex differences in CSA remained across all age groups for both fiber types with a larger sex difference in the middle aged and older adults than the young. Type II CSA decreased with age in females (32.4%) more than males (17.7%). Sex differences were present in fiber type I and II distribution in young only but present in proportional area in all age groups. The sex differences in fiber type characteristics remained in active and inactive people across muscles. These data suggest that (1) the greater loss of type II fiber CSA in females than males, may explain the larger relative declines in muscle strength and power after menopause compared with older males, and (2) there are inherent and robust biological sex differences in muscle fiber characteristics in whole skeletal muscle across the lifespan.

Purpose
Caloric restriction and excessive exercise create an energy imbalance with medical
sequelae in restrictive eating disorders. We examined the effect of acute and chronic energy
imbalance on admission illness severity and refeeding outcomes in adolescents and young adults with anorexia nervosa (AN) and atypical AN.

Methods
Secondary data analysis from the Study of Refeeding to Optimize Inpatient Gains, a multicenter randomized trial comparing higher- versus lower-calorie refeeding in 120 youth with AN or atypical AN hospitalized with medical instability. Vital signs were measured daily. Acute energy balance was calculated as caloric output (exercise recall plus estimated resting energy expenditure) subtracted from caloric input (dietary recall) before admission. Chronic energy imbalance variables included magnitude, rate, and duration of weight loss before admission. Regression analyses examined associations among energy balance, illness severity, and refeeding outcomes; dominance analyses examined the relative importance of energy balance.

Results
Among 82 participants (91% female), admission mean (SD) age was 16.5 (2.5) years, %median body mass index was 85 (10) and acute energy balance was -898 (678) kilocalories. Those with more negative acute energy balance before admission required more days (-0.18, [95% CI, -0.35, -0.02] p = .03) and kilocalories to restore medical stability (-431.10, [95% CI, -857.06, -5.13] p = .047). Acute energy balance was a more important predictor than weight suppression in determining these outcomes.

Osteoarthritis (OA) is a whole-joint disease involving cartilage, subchondral bone, and muscles. Women are disproportionately impacted, with higher prevalence, faster progression, and greater symptom burden than men. While structural changes are well studied, early cellular and molecular processes—and their sex-specific differences—remain less understood. [18F]NaF PET enables in vivo assessment of bone remodeling, and hybrid PET-MRI allows simultaneous evaluation of bone, cartilage, and muscle. The study investigated how sex, age and BMI, influence bone metabolism, cartilage microstructure, and muscle composition in asymptomatic adults.

71 adults (18-80 yrs, 36F) without knee injury or OA underwent knee imaging on a 3T PET-MRI. Cartilage T2 and thickness were derived from MRI across femoral, tibial, and patellar regions for deep and superficial layers. [18F]NaF PET scans, acquired before and after stair climbing, measured SUVmean, SUVmax, and exercise-induced changes (ΔSUV). Bilateral thigh IDEAL (Dixon) scans quantified muscle maximum cross-sectional area (CSA) and fat fraction. Associations with sex, age, and BMI were tested using linear mixed-effects models (p<0.05).

Hybrid [18F]NaF PET-MRI revealed key sex-specific differences: women showed greater exercise-induced bone uptake, lower muscle CSA, and higher fat fraction, suggesting distinct remodeling demands and reduced muscle quality that may heighten OA risk. Age was consistently associated with smaller CSA, greater fat infiltration, higher bone metabolism, and higher cartilage T2 values, indicating progressive declines in muscle, bone, and cartilage health. BMI was linked to larger CSA and higher fat fraction, and higher bone uptake responses.

These findings underscore that women experience unique bone and muscle changes contributing to their greater OA burden and highlight the value of integrated PET-MRI biomarkers for understanding early disease pathways and guiding sex-specific prevention strategies.

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.

Background
Differences in running-related injury risk and type may stem from sex-specific gait mechanics that may reflect distinct strategies for managing impact shock-related loads. Purpose. Examine if sagittal plane knee and ankle joint mechanics (i.e., proposed active shock attenuation mechanisms) enable low frequency (3-8 Hz), resultant shock attenuation to varying degrees in male than female runners.

Methods
33 male and 24 female runners, 18-65 years old, running 3-30 mi•wk-1 ran overground at 3.35 m•s− 1 as impact shock was measured at the distal tibia and low-back using inertial measurement units with triaxial accelerometers. Frequency domain resultant shock attenuation was computed between the low-back relative to the tibia via a transfer function of the power spectral density within 3-8 Hz. Unadjusted and age-adjusted linear regressions (α=0.05) tested the interaction effects of sagittal plane ankle and knee mechanics with sex on low-frequency shock attenuation.

Results
Attenuation was comparable between sexes without (p=0.66, CI=-9.89 – 6.34) and with (p=0.052, CI=-0.002 – 0.52) age adjustments. Prior to age adjustments, attenuation increased with an increase in knee flexion at contact in females (p=<0.01, CI=-3.50 – -0.57) but not males (p=0.90, CI = -1.04 – 1.17), decreased as ankle stiffness increased in females (p=<0.01, CI=2.05 – 9.07) not males (p=0.38, CI=-1.40 – 3.57), and decreased as knee range of motion increased in females (p=<0.01, CI=0.59 – 2.81) not males (p=0.78, CI=-1.49 – 1.14). Age adjustments rendered the interaction effects of sex with ankle stiffness (p=0.05, CI=-0.11 – 8.40) and knee contact angle (p=0.05, CI=-3.61 – 0.04) on resultant shock attenuation non-significant.

Conclusions
Associations of select ankle and knee mechanics, to resultant low-frequency shock attenuation may vary by sex, and together with age and known sex-specific effects of body composition, suggest that the body’s response to impact shock is sex-dependent.

Introduction
Urinary incontinence is common in young, nulliparous female elite athletes, but the effects of high-intensity exercise on the pelvic floor are not well understood. We examined urinary symptoms and associated pelvic floor anatomy and function in this population, hypothesizing that athletes with UI would exhibit pelvic floor findings seen in older incontinent women (eg, pelvic floor descent and urethral hypermobility) and findings attributable to elite sporting such as muscle hypertrophy.

Methods
We performed a cross-sectional study of National Collegiate Athletic Association Division 1 nulliparous female athletes comparing symptomatic (i.e. currently or previously experienced urinary leakage during exercise) and asymptomatic athletes. Athletes underwent pelvic exam and pelvic MRI assessing the pelvic floor at rest and at maximal strain. We also assessed demographics, sport characteristics, relevant medical history, and validated genitourinary symptom questionnaires (Lower Urinary Tract Dysfunction Network Symptom Index-29, LURN SI-29; Female Genitourinary Pain Index, GUPI). Data were compared between groups using the Wilcoxon rank sum, Pearson Chi-square, and Fisher exact tests as appropriate.

Results
Of 29 athletes (11 asymptomatic, 18 symptomatic), demographics, sport characteristics, and pelvic exam findings were not statistically different between groups. Symptomatic athletes had significantly worse urinary symptoms (median LURN SI-29 8.5 vs. 8.0, P=0.022) and genitourinary pain (median GUPI 7 vs. 3, P=0.036), greater anterior thickness of the striated urethral sphincter muscle (median 2.5 vs. 1.8 mm, P=0.016) and puborectalis and levator ani muscles (median 10.3 vs. 8.6 mm, P=0.028), and worse disordered eating (median BEDA-Q 7.5 vs. 4.5, P=0.022).

Conclusions
In nulliparous female elite athletes with UI, dynamic pelvic MRI identified differences in pelvic floor anatomy, which may be part of a multifactorial etiology of UI.