Methodology Review: A Protocol to Audit the Representation of Female Athletes in Sports Science and Sports Medicine Research

Impact of the menstrual cycle phases and time of day on markers of stress: salivary α-amylase and secretory immunoglobulin A

Previous reports suggest that the menstrual cycle (MC) phases can impact cortisol concentrations. However, research is needed on whether the MC impacts other markers of stress and immune function. It has also been shown that some biomarkers are impacted by time of day, although differences between morning (AM) and afternoon (PM) biomarkers have not been studied over the course of the MC. This study assessed the effect of MC phases and time of day on salivary stress biomarkers [salivary α-amylase (sAA), secretory immunoglobulin A (SIgA)], progesterone, resting blood pressure and resting heart rate (RHR). A single-group repeated measure design was employed in which seventeen participants (n = 17) monitored their MC for two months while attending eight experimental sessions which included both AM and PM sessions during each predicted 1) menses, 2) follicular, 3) ovulatory and 4) luteal phases. Resting blood pressures, heart rates, body composition parameters (assessed via bioelectrical impedance analysis), sAA and SIgA concentrations were assessed. No time of day x MC phase interactions (p > 0.05) were noted for sAA or SIgA, resting blood pressure, heart rate, or body composition parameters. However, sAA and RHR were significantly higher in the PM, while SIgA was significantly higher in the AM. These data suggest that the MC phases do not impact sAA or SIgA, resting blood pressure, heart rates, or body composition parameters. However, time-of-day impacts RHR and concentrations of sAA and SIgA. These findings provide implications for female participants in research dealing with these biomarkers.

Fueling Soccer Players: A Scoping Review and Audit of Literature Related to Soccer-Specific Guidelines for Carbohydrate Intake

BACKGROUND

Professional soccer players are advised to consume 3-8 g kg-1 body mass day-1 of carbohydrate (CHO) on the basis of training demands, fixture schedule and personal objectives. However, owing to the lack of randomized controlled trials on elite players, these guidelines largely rely on data interpretation and practitioner experience.

OBJECTIVE

To identify the gaps in existing literature that inform CHO guidelines for soccer players.

METHODS

A scoping review was conducted without date restrictions up to 21 March 2024, employing a three-step search strategy to identify relevant English-language primary and secondary articles through PubMed and reference searching. Data were extracted using a standardized audit tool from studies assessing direct and indirect impacts of CHO on soccer players' performance and health.

RESULTS

Within 258 studies identified, experimental studies were the most common (~ 36%), followed by observational (~ 33%) and narrative reviews (~ 26%), with systematic reviews, meta-analyses and case studies making up the rest (~ 5%). Most observational studies were field-based (~ 98%), while experimental studies were laboratory-based (~ 75%). Among 4475 participants, ~ 16% were female, and only ~ 12% of the original research was exclusively conducted on female players. Observational studies included developmental (~ 52%) and professional players (~ 31%), whereas experimental studies primarily featured recreationally active (~ 40%) and collegiate/university participants (~ 26%). Key research topics were 'dietary intake' (~ 52%) and "energy expenditure and dietary intake" (~ 30%) for observational studies and 'CHO interventions' (~ 74%) for experimental studies. Only eight experimental studies exclusively involved professional players, focusing on CHO intervention (n = 7) and CHO co-ingestion (n = 1). Narrative reviews were published in journals with higher impact factor (4.1 ± 6.4) than were observational studies (3.2 ± 1.6, p < 0.001) and experimental studies (3.4 ± 1.6, p < 0.001). Narrative reviews had the most studies, with Altmetric scores ≥ 20 (n = 26), followed by experimental (n = 16) and observational studies (n = 14).

CONCLUSIONS

Current CHO guidelines for elite soccer players lack experimental research specific to professional and world-class players. More field-based experimental trials involving elite soccer players are required to ensure evidence-based CHO recommendations.

Less than 4% of participants in studies of carbohydrate-based fuelling strategies for soccer performance have been female: results from an audit of her representation

Women's soccer has increased markedly in popularity and professionalisation in recent years. Achieving adequate carbohydrate (CHO) availability before and during performance is often advised as a key priority for players. The aim of this study was to audit the literature that informs the current CHO-based guidelines for soccer performance and to assess the extent of evidence supporting their application to female players. Using an established protocol for auditing the published literature, seven databases were searched for research investigating the effects of acute CHO-based fuelling strategies before or during soccer performance. A total of 43 studies met the inclusion criteria. There were a total of 542 participants, of which 3.7% were female (n = 20 individuals) and 96.3% were male (n = 522 individuals). The majority of the studies were designed to examine the effects of CHO intake during soccer (n = 31; 72.1%), with the remaining studies employing pre-exercise CHO intake (n = 5; 11.6%) or CHO loading (n = 7; 16.3%) protocols. Most studies involved male-only cohorts (n = 41; 95.3%), while female-only (n = 1; 2.3%) and mixed-sex cohorts (n = 1; 2.3%) were less prevalent. Of the two studies that included females, neither provided any information around categorisation or control of menstrual cycle status. The current guidelines on acute CHO-based fuelling strategies for soccer are not informed by an adequate evidence base when applied to female players. Given the potential for between-sex differences in physiology and metabolism, the lack of female-specific research means that it is presently unknown whether the current guidelines on CHO-based fuelling strategies for soccer are optimal for female players.

Female Athletes Report Positive Experiences as Research Participants

Given the underrepresentation of women in sports and exercise science research, we sought to understand the experiences of female athletes currently involved in applied sports and exercise science research to inform future studies and potentially increase participation rates. Accordingly, we investigated the experiences of 89 female athletes (n = 48 cyclists/triathletes, n = 19 race walkers, n = 22 National Rugby League Indigenous Women's Academy players) who participated in four separate studies of sports performance with different methodological characteristics. Participants completed a questionnaire upon study completion that queried prior research participation, reasons for participating and experiences during the current study. Across all 89 athletes, 81% were first-time research participants, with the primary barriers cited as a perceived lack of opportunities or being unaware of opportunities (93%). Participants rated an interest in the research outcome as the most important aspect influencing their decision to participate (90 ± 14 [out of 100]), followed by the opportunities to receive personalized results (84 ± 20) and education (78 ± 27). Most participants (87%) stated that they would apply the study findings to their sports involvement, while the remaining 13% reported that they required support to understand the application of results. The majority (94%) of participants indicated a willingness to participate in future studies, while the research experience was rated positively at a mean 77 out of 100. Ultimately, our findings uncovered a perceived lack of opportunity as the primary barrier to female athlete research participation. As such, opportunities for women to participate in high-quality studies should be prioritized.

Female Exercise Metabolism: Quality Assessment of Existing Knowledge Base and Key Challenges in Study Design

A better understanding of the practical and methodological challenges inherent in accurately tracking female hormonal status would enhance the clarity of research findings in exercise metabolism. The purpose of this study was to conduct an objective assessment of the quality of existing literature in this area and to provide a general overview of the practical conditions and issues encountered in studies investigating substrate metabolism during exercise in women, both in those using (HC+) or not using (HC-) hormonal contraceptives. Forty-four articles were identified through systematic reviews, meta-analyses, and searches on PubMed/MEDLINE. A quality assessment framework was developed and applied using a double-blind scoring approach. The loss/exclusion of data between baseline and final analyses per study was quantified, and the main challenges were highlighted. A higher mean global score was observed in studies conducted among HC+ women (81%) than those among HC- women (46%). Although the dropout rates were rarely mentioned in HC+ women articles, the mean rate of participant/data loss in HC- groups was 22.1%. The rate of HC- participant loss was positively correlated with the global score (r = .504, p = .02). High-quality research may be easier to achieve in studies involving HC+ women compared with those involving HC- women. Studies on HC- women seem to face more practical challenges, such as tracking the menstrual cycle and targeting specific (sub)phases of the menstrual cycle, along with technical and feasibility limitations. Thus, although the framework for designing such studies exists, the quality assessment of the available literature emphasizes its challenge in terms of research implementation.

Sex Differences in the Variability of Physical Activity Measurements Across Multiple Timescales Recorded by a Wearable Device: Observational Retrospective Cohort Study

BACKGROUND

A substantially lower proportion of female individuals participate in sufficient daily activity compared to male individuals despite the known health benefits of exercise. Investment in female sports and exercise medicine research may help close this gap; however, female individuals are underrepresented in this research. Hesitancy to include female participants is partly due to assumptions that biological rhythms driven by menstrual cycles and occurring on the timescale of approximately 28 days increase intraindividual biological variability and weaken statistical power. An analysis of continuous skin temperature data measured using a commercial wearable device found that temperature cycles indicative of menstrual cycles did not substantially increase variability in female individuals' skin temperature. In this study, we explore physical activity (PA) data as a variable more related to behavior, whereas temperature is more reflective of physiological changes.

OBJECTIVE

We aimed to determine whether intraindividual variability of PA is affected by biological sex, and if so, whether having menstrual cycles (as indicated by temperature rhythms) contributes to increased female intraindividual PA variability. We then sought to compare the effect of sex and menstrual cycles on PA variability to the effect of PA rhythms on the timescales of days and weeks and to the effect of nonrhythmic temporal structure in PA on the timescale of decades of life (age).

METHODS

We used minute-level metabolic equivalent of task data collected using a wearable device across a 206-day study period for each of 596 individuals as an index of PA to assess the magnitudes of variability in PA accounted for by biological sex and temporal structure on different timescales. Intraindividual variability in PA was represented by the consecutive disparity index.

RESULTS

Female individuals (regardless of whether they had menstrual cycles) demonstrated lower intraindividual variability in PA than male individuals (Kruskal-Wallis H=29.51; P<.001). Furthermore, individuals with menstrual cycles did not have greater intraindividual variability than those without menstrual cycles (Kruskal-Wallis H=0.54; P=.46). PA rhythms differed at the weekly timescale: individuals with increased or decreased PA on weekends had larger intraindividual variability (Kruskal-Wallis H=10.13; P=.001). In addition, intraindividual variability differed by decade of life, with older age groups tending to have less variability in PA (Kruskal-Wallis H=40.55; P<.001; Bonferroni-corrected significance threshold for 15 comparisons: P=.003). A generalized additive model predicting the consecutive disparity index of 24-hour metabolic equivalent of task sums (intraindividual variability of PA) showed that sex, age, and weekly rhythm accounted for only 11% of the population variability in intraindividual PA variability.

CONCLUSIONS

The exclusion of people from PA research based on their biological sex, age, the presence of menstrual cycles, or the presence of weekly rhythms in PA is not supported by our analysis.

Female Patient Representation Is Acceptable in Studies Regarding Hip Arthroscopy With Labral Repair Yet Deficient in Key Study Design and Sport-Specific Features

Purpose

To systematically review and examine the current literature regarding the representation of female athletes in studies examining arthroscopic hip labral repair procedures.

Methods

Studies regarding arthroscopic hip labral repair were identified in PubMed. We included human studies of all levels of evidence written in English that identified the biological sex of study participants and were conducted in the United States or non-US countries that offer the same treatment strategies available in the United States. Data regarding study population, athletic caliber, menstrual status, research theme, sample of males and females, journal impact factor, and paper Altmetric score were recorded and analyzed.

Results

We screened 1,152 studies and identified 62 to be included in this audit. Females made up 55% of the population of participants. Female-only and male-only studies represented 4.8% and 14.5% of studies investigated, respectively. No studies investigated outcomes of female participants at the highest athletic caliber. Menstrual status was not considered or included as a variable in any study. Participants within athletic performance, indirect association, and health research theme had 32.8%, 61.1%, and 58.6% female representation, respectively. Median impact factor was similar among study population classifications. Study Altmetric score was highest among male-only studies and studies of the highest levels of athletic caliber.

Conclusions

Overall, there was a similar prevalence of female-to-male participants in hip labral repair research, with a 55% to 45% female-to-male ratio in all studies included in this review. Despite this, there is a lack of female-only studies, inclusion of menstrual status, high-level female athletes, and female participants evaluated for performance outcomes.

Level of Evidence

Level IV, systematic review of Level I to IV studies.

Effect of intravenous iron therapy on exercise performance, fatigue scores and mood states in iron-deficient recreationally active females of reproductive age: a double-blind, randomised control trial (IRONWOMAN Trial)

OBJECTIVES

Non-anaemic iron deficiency (IDNA) is highly prevalent in exercising females. Although iron therapy can be used to correct this issue, its impact on exercise performance is equivocal. Our aim was to assess the efficacy of intravenous iron therapy on exercise performance, fatigue, mood states, and quality of life in recreationally active IDNA females of reproductive age.

METHODS

Twenty-six recreationally active IDNA females were randomised to either an intravenous iron treatment (IRON) group or placebo (PLA). Prior to, 4 days and 4 weeks following intervention, participants completed a variety of assessments to determine changes in exercise performance, haemoglobin mass, blood iron status and haematology, fatigue levels, mood states and quality of life.

RESULTS

Intravenous iron therapy significantly improved serum ferritin, serum iron and transferrin saturation (p<0.05), with a highly variable individual response. No differences were observed between groups' peak oxygen consumption (V̇O2Peak), lactate threshold or haemoglobin mass. Running economy improved in IRON from baseline to 4 weeks (p<0.05), which was also different to PLA at 4 weeks (p<0.05). Fatigue scores improved in IRON but not PLA after 4 weeks (p<0.05). Mood states and quality of life remained unchanged in both groups over the trial.

CONCLUSION

In recreationally active IDNA females, intravenous iron therapy corrects iron status and improves both exercise economy and fatigue scores after 4 weeks.

TRIAL REGISTRATION NUMBER

ACTRN12620001357943.

Perceived Negative Menstrual Cycle Symptoms, But Not Changes in Estrogen or Progesterone, Are Associated with Impaired Cycling Race Performance

PURPOSE

To examine the relationship between menstrual cycle (MC) phase-dependent fluctuations of estrogen and progesterone and virtual cycling race performance, with a secondary aim of correlating perceived MC-related symptoms with performance.

METHODS

In a novel observational study design, 37 female cyclists/triathletes not using any hormonal contraception completed one virtual cycling race (19.5-km time trial (TT)) per week across a 1-month period (totaling four races). Participants completed MC characterization and tracking, including urinary ovulation kits, across two complete MCs. Venous blood samples were collected within 21 h of racing to determine serum 17-β-estradiol and progesterone concentrations, as well as an assessment of self-reported, perceived race-day MC and gastrointestinal (GI) symptoms, which were all then correlated to race performance.

RESULTS

There was no relationship between race completion time and individual estradiol ( r = -0.001, P = 0.992) or progesterone ( r = -0.023, P = 0.833) concentrations. There was no difference between race time between MC phases (follicular/luteal, P = 0.238), whether MC bleeding or not bleeding ( P = 0.619), and whether ovulating or not ovulating ( P = 0.423). The total number of perceived MC symptoms recorded on race day was positively correlated to increased race time ( r = 0.268 (95% confidence interval, 0.056-0.457), P = 0.014), as was the number of GI symptoms of at least "moderate" severity before the race ( r = 0.233 (95% confidence interval, 0.021-0.425), P = 0.031), but not post-race ( r = 0.022, P = 0.841).

CONCLUSIONS

When implementing a novel, virtual cycling race, fluctuations in ovarian hormone concentrations across the MC do not appear to affect real-world cycling performance among trained cyclists, whereas perceived negative MC and GI symptoms may relate to impaired performance. Therefore, the management of negative MC and GI symptoms appears important for athletic performance enhancement or to mitigate performance decline.

The race within a race: Together on the marathon starting line but miles apart in the experience

Every four years the world's best athletes come together to compete in the Olympic games, electrifying audiences with incredible feats of speed, strength, endurance and skill as personal best performances and new records are set. However, the exceptional talent that underpin such performances is incomprehensible to most casual observers who often cannot appreciate how unique these athletes are. In this regard, endurance running, specifically the marathon, a 42.195 km foot race, provides one of the few occasions in sport outside of Olympic, world and national competitions, that permits sport scientists and fans alike to directly compare differences in the physiology between recreational and elite competitors. While these individuals may all cover the same distance, on the same course, on the same day - their experience and the physiological and psychological demands placed upon them are vastly different. There is, in effect, a "race within a race". In the current review we highlight the superior physiology of the elite endurance athlete, emphasizing the gap between elite competitors and well-trained, but less genetically endowed athletes. We draw attention to a range of inconsistencies in how current sports science practices are understood, implemented, and communicated in terms of the elite and not-so-elite endurance athlete.

Where Are All the Female Participants in Sports and Exercise Medicine Research? A Decade Later

BACKGROUND

In 2014, Costello and colleagues published a sentinel paper spotlighting the large disparity of female versus male representation within sports science and sports medicine (SSSM) research.

PURPOSE

To (1) revisit the method published by Costello et al a decade later to evaluate female representation and (2) ascertain whether study designs account for menstrual status.

STUDY DESIGN

Systematic Review; Level of evidence, 4.

METHODS

All original and epidemiologic research of live human participants from the journals Medicine and Science in Sports and Exercise, British Journal of Sports Medicine, and the American Journal of Sports Medicine were included from January 2021 to August 2023. Number of male and female participants for each study was analyzed. A menstrual-status tiering system published by Smith et al was used to classify the consideration of female participants' menstrual status in study design.

RESULTS

A total of 1441 studies and 40,152,860 participants were included in this analysis. This included 17,648,509 (43.95%) female participants. The mean proportion of female participants per study was 40.22%, and 103 (7.15%) studies included only female participants compared with 268 (18.6%) male-only studies. A total of 66 (5.6%) studies included menstrual-status considerations in their study design with 7.7 (0.7%) and 5.5 (0.5%) receiving a silver or gold classification, respectively, for design considerations.

CONCLUSION

Our investigation into the representation of female athletes in SSSM research found an increase in female participation from 39% to 43.95% of total participants over the past decade. While the overall number of female participants rose in the years 2021 to 2023, there remains a significant disparity in female representation in SSSM research compared with male participants. Additionally, we found that the inclusion of menstrual status in study designs has been limited, with few studies considering this crucial variable.

GPS External Load Metric Data and Game Performance in NCAA Division I Women's Lacrosse Athletes: A Longitudinal Study

This study investigates the relationship between GPS-derived external load metrics and game performance (win/loss) in NCAA Division I women's lacrosse athletes. Utilizing data from three seasons (2022-2024), the study analyzed 1,687 observations from 54 players to identify key performance indicators correlating with game outcomes. GPS metrics including Total Distance (TD), High-Speed Distance (HSD), Very High-Speed Efforts (VHSE), Total Player Load (TPL), High Inertial Movement Analysis (High IMAs), and Total Acceleration Load (TAL) were assessed. Multivariate logistic regression results indicate that VHSE is the most significant predictor of game success, with VHSE showing a positive correlation with winning outcomes (p = 0.007; OR = 1.017, 95% CI [1.005, 1.030]). Although other metrics like TD and TPL were significant in univariate models, their impact diminished in multivariate analysis, suggesting their effects are intertwined with other performance factors. The study highlights the importance of high-intensity efforts in game outcomes and provides insights for optimizing training strategies for female lacrosse athletes. These findings underscore the need for continued research into female athlete performance to better inform sport-specific training programs and enhance competitive success.

Longitudinal Analysis of Subsequent Musculoskeletal Injuries and Predictive Value of Index Injuries in Collegiate Women's Field Hockey

This study investigates the longitudinal patterns of musculoskeletal injuries in an NCAA field hockey team, emphasizing the predictive value of index injuries on subsequent injury rates. Analyzing a dataset from a women's collegiate field hockey team, this research monitored 810 injuries across 124 athletes from 2008 to 2024. The study categorized injuries as local, nonlocal, and recurrent, employing a negative binomial regression to assess the impact of index injuries on the total number of career injuries. Results indicated that ankle sprains, hamstring strains, and back strains significantly predicted the total number of career injuries. Furthermore, the analysis revealed that the majority of subsequent injuries occurred within 69 days of the index injury, suggesting a critical window for targeted interventions. The findings underscore the need for robust longitudinal data and standardized reporting to enhance injury prevention strategies in field hockey.

Menstrual-Cycle and Hormonal-Contraceptive Tracking in Gaelic Football: From the Lab to the Field

PURPOSE

The purpose of this study was to describe the implementation of menstrual-cycle (MC) and hormonal-contraceptive (HC) tracking among Gaelic Football players, including the characterization of MC status and symptomatology, and to examine the effect of MC and oral-contraceptive-pill phases on daily wellness.

METHODS

Fourteen highly trained players (age 24.2 [3.5] y), including non-HC (n = 6), oral contraceptive pill (n = 7), and intrauterine system (n = 1) users, prospectively tracked their MC or HC alongside daily self-reported wellness measures for 4 months. A combination of calendar-based counting, urinary ovulation prediction testing, and a midluteal serum progesterone measurement was used to assess MC status.

RESULTS

Only 2 non-HC players were eumenorrheic. Two players exhibited oligomenorrhea (cycle length, 39 [4] d), and ovulation was not detected in one of them. Luteal phase deficiency was indicated in 2 players (serum progesterone range <1.0-7.5 nmol·L-1). All players except 1 reported at least 1 negative MC-related symptom or HC side effect. Linear mixed-model analyses revealed that wellness measures were not affected by oral contraceptive pill phase (P > .05). Linear mixed-model analysis was not performed in non-HC users due to the small sample of eumenorrheic players (n = 2).

CONCLUSIONS

Diverse reproductive profiles were observed, including HC use and subtle MC irregularities that would likely go undetected without prospective MC tracking using biochemical outcomes. This highlights the value of incorporating ovulation testing and blood sampling when establishing the MC status of athletes in applied research and practice where feasible. Applied researchers should anticipate practical challenges, including inconsistencies in ovulation testing timings and the time scale required to assess MC status among athletes.

Effect of Beetroot Juice Supplementation on Aerobic Capacity in Female Athletes: A Randomized Controlled Study

Background/Objectives: This study addresses the growing interest in nutritional supplements that improve athletic performance in endurance sports. Previous research suggests that nitrates in beetroot juice enhance blood vessel dilation and oxygen delivery to muscles. However, the effects of these nitrates on cardiopulmonary performance in female athletes remain underexplored. The aim of this study was to evaluate the effect of beetroot juice supplementation on aerobic work capacity in female endurance athletes. Methods: A cardiopulmonary exercise test (CPET) was conducted to assess aerobic work capacity. Eighteen healthy female endurance athletes (22.9 ± 5.6 years) participated in the study. The participants were randomly assigned to two groups: the control group (placebo group n = 9), which received a nitrate-free placebo beverage, and the experimental group (beetroot juice group n = 9), which consumed 50 mL of beetroot juice concentrate (~6.2 mmol nitrate) two and a half hours before the second test. Results: The results showed that the beetroot juice group demonstrated significant improvements in minute ventilation (VE), respiratory equivalents (VE/VO2 and VE/VCO2), and heart rate (HR) (p < 0.05). Maximal oxygen consumption (VO2 max) increased by 4.82% in the beetroot juice group (from 35.24 ± 5.07 to 36.94 ± 4.91 mL·min-1·kg-1), whereas a small decrease was observed in the placebo group. Conclusions: These findings indicate that beetroot juice may be an effective ergogenic aid, enhancing oxygen utilization and energy production during exercise in female athletes. In terms of practical applications, beetroot juice could contribute to improved athletic performance and serve as a valuable addition to athletes' nutritional plans. Future studies should explore the long-term effects, optimal dosages, and duration of supplementation in larger and more diverse populations.

Sex and gender in sports nutrition research: bridging the gap

The Olympic Games have grown to be the largest, gender-equal sporting event in the world, and the International Olympic Committee is committed to gender equality in sports encouraging and supporting the promotion of women in sports at all levels and in all structures with a view to implementing the principle of equality of men and women (IOC, 2023). Women competed for the first time at the 1900 Olympic Games in Paris, and the number of women competing has grown exponentially over the last 100 years, so an estimated 5494 female athletes (48 %) competed in the Summer Olympic Games 2021 in Tokyo. Supporting women (alongside men) in achieving optimum performance is crucial, and understanding that there are sex and gender gaps in sports nutrition research is important. One reason for this gap is the historical bias in sports and exercise science research towards male participants. This has led to a poor understanding of the unique physiological and nutritional needs of female athletes. In summary, a balanced approach is crucial to address the nutritional needs of both male and female athletes. Researchers should continue exploring this important area to optimise performance and health for all athletes. The aim of this review is to summarise current sports nutrition literature and highlight research that seeks to understand and address where the gaps are with respect to several key areas in sports nutrition recommendations that can impact advice and practice with both males and females.

Female Athletes Are Underrepresented in Anterior Cruciate Ligament Reconstruction Rehabilitation Studies: A Systematic Review

PURPOSE

To systematically review the representation of female athletes in the current primary literature available on rehabilitation after anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic review was conducted using PubMed to provide a comprehensive analysis of female representation in ACLR postoperative rehabilitation protocols. Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed. Studies were analyzed based on nine factors: study population, athletic caliber, menstrual status, research theme, journal impact factor, sample size of male and female participants, time to return to sport, and graft failure rate. Population categories included males-only, females-only, mixed-sex, and male vs. female comparisons. Athletic caliber had 6 tiers. Menstrual status was categorized as natural, hormonal contraception, irregularities, mixed, or unclassified. Research themes were health-focused, performance-focused, or combined. Study impact was assessed via journal impact factor.

RESULTS

Thirty-three studies were included. Females comprised 3031/6798 (44.6%) of ACLR participants. No female-only studies were found; male-only studies accounted for 3 of 33 (9%), mixed-sex for 25 of 33 (69.7%), male versus female subanalysis for 3 of 33 (9%), and male versus female features for 2 of 33 (6%). No studies investigated outcomes for the highest athletic levels. Menstrual status was not considered. No studies focused on performance outcomes; 25 of 33 (69.7%) had a health research focus. Female athletes were under-represented in studies evaluating return to sport timeline and graft failure rate.

CONCLUSIONS

Female athletes face a 2 to 8 times greater risk of ACL injury but are under-represented in ACLR postop rehabilitation studies, with only 44.6% participation compared with 55.4% for male athletes. In 9 studies, female athletes comprised 30% or less of participants. Even studies including female athletes at near-equal rates failed to address menstrual status or sex hormones on injury and rehabilitation.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Ethical Risks of Systematic Menstrual Tracking in Sport

In this article it will be concluded that systematic menstrual tracking in women's sport has the potential to cause harm to athletes. Since the ruling of Dobbs v. Jackson Women's Health Organization (2022) in the United States, concerns regarding menstrual health tracking have arisen. Research suggests that the menstrual tracking of female athletes presents potential risks to "women's autonomy, privacy, and safety in sport" (Casto 2022, 1725). At present, the repercussions of systematic menstrual tracking are particularly under-scrutinized, and this paper seeks to combine novel research in the sport sciences with present ethical debates in the philosophy of sports. Utilizing Beauvoir's feminist philosophy (2011), this paper argues that systematic menstrual tracking may contribute to the wider system of women's oppression by exploiting female athletes, as well as enabling the internalization of submissive behaviour in cultures where athletes are expected to comply unquestioningly. Five policy recommendations are made concerning autonomy, informed consent, education, safeguarding and data access. The overall findings of this paper propose that a more in-depth understanding of the links between data, privacy, and the menstrual cycle are required by sports organizations and governing bodies if athletes are to be protected in a future where systematic menstrual tracking is inevitable.

Influence of acute heat mitigation strategies on core temperature, heart rate and aerobic performance in females: A systematic literature review

This review examined the effect of acute heat mitigation strategies on physiological strain and exercise performance in females exercising in the heat. Three databases were searched for original research with an acute heat mitigation (intervention) and control strategy in active females and reporting core temperature, heart rate and/or aerobic exercise performance/capacity with ≥ 24°C wet bulb globe temperature. Hedges' g effect sizes were calculated to evaluate outcomes. Thirteen studies (n = 118) were included. Most studies that applied an acute heat mitigation strategy to females did not reduce thermal (9/10) or cardiovascular (6/6) strain or improve exercise performance/capacity (8/10). The most effective strategies for attenuating thermal strain were pre-cooling with ice-slurry (effect size = -2.2 [95% CI, -3.2, -1.1]) and ice-vests (-1.9 [-2.7, -1.1]), and pre- and per-cooling with an ice-vest (-1.8 [-2.9, -0.7]). Only pre-cooling with an ice-vest improved running performance (-1.8 [-2.9, -0.7]; ~0.43 min) whilst sodium hyperhydration improved cycling capacity at 70% V O2peak (0.8 [0.0, 1.6]; ~20.1 min). There is currently limited research on acute heat mitigation strategies in females, so the evidence for the efficacy is scarce. Some studies show beneficial effects with ice-slurry, ice-vests and sodium hyperhydration, which can guide future research to support female exercise performance in the heat.

Hormonal Contraceptive Influence on Baseline Vestibular/Ocular Symptomatology and Provocation for Concussion

Background

Hormonal contraceptives (HCs) and the menstrual cycle have been suggested to affect symptom severity and postconcussion recovery. Additionally, hormones have been a suggested rationale for sex differences between female and male athletes on concussion assessment. Researchers have yet to explore the effects of HC use on baseline symptomatology, including symptom reporting and provocation.

Purpose

To examine the influence of HC use on a baseline symptom reporting and vestibular/ocular provocation battery.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 61 college-aged individuals (21 HC-using women, 21 non-HC-using women, 19 men) were administered a baseline symptom battery consisting of the Post-Concussion Symptom Scale (PCSS), Headache Impact Test-6 (HIT-6), Pediatric Vestibular Symptom Questionnaire (PVSQ), and Vestibular/Ocular Motor Screening (VOMS). The main outcome measures consisted of PCSS symptom reporting (total symptoms, symptom severity score, and symptom factors), HIT-6 and PVSQ total scores, and VOMS item (ie, saccades, convergence, or vestibular/ocular reflex) symptom provocation scores.

Results

Significant differences were reported on HIT-6, with the highest headache reporting in the HC group (P = .026). On the PVSQ, the HC group also reported greater dizziness and unsteadiness symptoms than the non-HC group (P = .023). Similar findings existed on the PCSS, with the HC group reporting greater total symptoms (P < .001), symptom severity (P < .001), and vestibular-somatic (P = .024), cognitive-sensory (P = .004), sleep-arousal (P = .001), and affective (P < .001) factors compared with the non-HC group. Smooth pursuit (ie, following finger smoothly with eyes) was the only VOMS items with differences between groups (P = .003), with the HC group having greater provocation compared with non-HC users (P = .020).

Conclusion

HC use was associated with overall symptomatology and worse self-reported symptoms on vestibular-related inventories and concussion symptom scales and factors when compared with non-HC users and male controls. Additionally, HC users reported higher VOMS provocation scores on the smooth pursuit item than non-HC users and male controls.

Inconsistencies in the perceived impact of the menstrual cycle on sport performance and in the prevalence of menstrual cycle symptoms: A scoping review of the literature

OBJECTIVES

This scoping review aimed to summarize the findings of studies regarding the perceived impact of the menstrual cycle on athletic performance, as well as the prevalence of negative menstrual cycle symptoms.

DESIGN

Scoping review.

METHODS

Three databases were searched and the Preferred Reporting Items for Systematic reviews and Meta Analyses extension for Scoping Reviews (PRISMA-ScR) was used as guidance.

RESULTS

A total of 39 studies were included in the final analysis. Between 2.8 and 100 % of athletes reported their performance being negatively impacted by their menstrual cycle, and the main reason was the occurrence of menstrual cycle symptoms. Additionally, a large variability in the prevalence of menstrual cycle symptoms was reported in the different studies mainly due to methodological differences and recall biases.

CONCLUSIONS

Similarly, as to what has been reported in reviews summarizing performance outcomes during different menstrual cycle phases, this review highlights the high degree of variability between how athletes perceive to be impacted by their menstrual/hormonal contraceptive cycle.

REGISTRATION

The protocol of this scoping review was registered at the Open Science Framework on 14 September 2023 (osf.io/efu9x).

Auditing the representation of hormonal contraceptives in studies assessing exercise performance in women

Hormonal contraceptive (HC) users have a different ovarian hormonal profile compared to eumenorrheic women. Due to the prevalence of HC use amongst sportswomen, there has been increased research efforts to understand their impact on exercise performance. The aim was to audit this research. Studies identified were assessed for HC type, athlete calibre, performance outcome, study design, and quality of methodological control regarding ovarian hormonal profiles. Sixty-eight different HCs were reported across 61 studies. Monophasic combined oral contraceptive (OCP) pills represented 60% of HCs, followed by other pills [34%, phasic-combined, progestogen-only, and un-specified], phasic and long acting reversible contraceptives [5%, vaginal ring, patch, implant, injection, intrauterine system] and unspecified HCs (1%). Eleven percent of participants using HCs were classified as highly trained or elite/international with no participants being classed as world class. Whilst the number of studies involving HCs has increased two-fold over the past decade, the number of studies ranked as gold standard has not increased (HC; 2003-57%, 2011-55%, 2022-43%. OCP; 2003-14%, 2011-17%, 2022-12%). Future research assessing HCs and exercise performance should adopt high-quality research designs and include a broader range of HCs in highly trained to world-class populations to increase the reach and impact of research in this area.

Female Athlete Research Camp: A Unique Model for Conducting Research in High-Performance Female Athletes

PURPOSE

The purpose of this study is to describe the implementation of a novel research protocol for conducting research with highly trained female athletes, including characterizing menstrual cycle (MC) function, hormonal profiles and symptoms of the participating athletes.

METHODS

Twenty-four Australian First Nation female Rugby League athletes completed this study, which involved 11 wk of cycle tracking, followed by attendance at a 5-wk training camp. Throughout the study, athletes completed a daily survey, reporting their MC function and any associated symptoms. During the training camp, athletes reported to the laboratory on three occasions and provided a venous blood sample, which was analyzed for reproductive hormones. For naturally cycling athletes (athleteNC, n = 11), this included phase 1, 2, and 4 of the menstrual cycle, whereas athletes using hormonal contraception (athleteHC; n = 13) were tested at three equally spaced time points in which consistent exogenous hormone provision occurred.

RESULTS

In the athleteNC cohort, just one athlete reached criteria for classification as eumenorrheic, with five athletes showing evidence of MC dysfunction. The prevalence of symptoms on any given day was similar between athleteNC (33.7%) and athleteHC (22.9%; P = 0.376); however, more symptoms were reported in athleteNC, suggesting that they were more likely to report multiple symptoms. Regardless of MC function, there was a significant, positive association between bleeding and symptoms ( P < 0.001), where athletes were more likely to report one or more symptoms on bleeding (50.1%) compared with nonbleeding days (22.0%).

CONCLUSIONS

We describe an innovative strategy to investigate the effect of MC function and MC phase in a high-performance sport environment, including approaches to address the challenges of undertaking research with female athletes with MC variability and those using exogenous hormonal therapies.

Vascular adaptation to exercise: a systematic review and audit of female representation

Biological sex is a salient factor in exercise-induced vascular adaptation. Although a male bias is apparent in the literature, the methodological quality of available studies in females is not yet known. This systematic review with narrative synthesis aimed to assess available evidence of exercise interventions on endothelial function, measured using flow-mediated dilation, in otherwise healthy individuals and athletes. A standardized audit framework was applied to quantify the representation of female participants. Using a tiered grading system, studies that met best-practice recommendations for conducting physiological research in females were identified. A total of 210 studies in 5,997 participants were included, with 18% classified as athletes. The primary exercise mode and duration were aerobic (49%) and acute (61%), respectively. Despite 53% of studies (n = 111) including at least one female, female participants accounted for only 39% of the total study population but 49% of the athlete population. Majority (49%) of studies in females were conducted in premenopausal participants. No studies in naturally menstruating, hormonal contraceptive-users or in participants experiencing menstrual irregularities met all best-practice recommendations. Very few studies (∼5%) achieved best-practice methodological guidelines for studying females and those that did were limited to menopause and pregnant cohorts. In addition to the underrepresentation of female participants in exercise-induced vascular adaptation research, there remains insufficient high-quality evidence with acceptable methodological control of ovarian hormones. To improve the overall methodological quality of evidence, adequate detail regarding menstrual status should be prioritized when including females in vascular and exercise research contexts.

Auditing the Representation of Female Athletes in Sports Medicine Research: Fifth-Metatarsal Fractures

Background

Female representation within athletics has increased as a result of Title IX, rising popularity, demand for equal compensation, and greater participation in multiple sports. Despite this, gender disparities in sports medicine research are apparent. This project serves to review the literature available on fifth-metatarsal fractures and assess the representation of female athletes in current literature.

Methods

We used a standardized protocol to audit the representation of female athletes in sports science and sports medicine research for fifth-metatarsal fractures. Primary factors included population, athletic caliber, menstrual status, research theme, sample of males and females, journal impact factor, and Altmetric score.

Results

Thirty articles met the inclusion criteria. A total of 472 fifth-metatarsal fractures were identified, with 373 of 472 fractures (79%) occurring in males and 99 of 472 (21%) in females. The majority of studies (18/30, 60%) were mixed cohort, followed by 10 male only (33.33%), 1 female only (3.33%), and 1 male vs female (3.33%). Out of 831 total patients in the 18 mixed-cohort studies, 605 of 831 patients (72.8%) were male and 226 of 831 patients (27%) were female. All 18 mixed-sex cohorts investigated health outcomes. Male-only studies evaluated health outcomes and performance metrics. No studies investigated female performance. The one female-only study investigated health outcomes and was the only study to account for menstrual status. There was a single metatarsal fracture in this study population.

Conclusion

Females are underrepresented in research regarding sports science and sports medicine research for fifth-metatarsal fractures. Research focused on female-only fifth-metatarsal fracture studies exploring the potential impact of female sex-specific factors such as menstrual status in study design are needed.

Auditing the Representation of Female Athletes in Sports Medicine Research: Achilles Repair

Background

Establishing evidence-based recommendations specific to female athletes has been overlooked in sports medicine. Achilles tendon rupture is one of the most common musculoskeletal injuries, occurring in 15 to 55 per 100 000 people annually. Differences in injury rates could be due to hormonal effects, as estrogen receptors have been identified in tendons along with decreased tendon strain based on oral contraceptive use. The primary purpose of this study was to audit the representation of female athletes in the literature regarding Achilles repair.

Methods

An electronic search was performed using PubMed to identify articles related to Achilles repair using the protocol by Smith et al. Studies were assessed by population, size, athletic caliber, study impact, research theme, and menstrual status.

Results

Female representation across all studies was 1783 of 10 673 subjects (16.7%). Composition of included studies was predominantly mixed-sex cohorts with 131 of 169 (77.5%) included studies. Within mixed-sex cohort studies, the total representation of female athletes was 1654 of 8792 participants (18.9%). Thirty-two studies were male only, constituting 1540 participants, whereas 3 studies were female only composed of 86 athletes. Importantly, the disparity between male and female representation worsened as the athletic caliber of the study population increased, with 5.0% female representation in studies with professional athletes. No study collected data related to menstrual status and its potential relationship to Achilles rupture or postoperative outcomes.

Conclusion

Mixed-sex cohort studies underrepresented female athletes, and male-only cohort studies were more common than female-only studies. These findings indicate a need for increased representation of female athletes as well as acknowledgment of menstrual status in research related to Achilles repair. Future studies should focus on representation of female athletes and data collection related to sex-specific hormones, hormonal contraceptive use, and menstrual status to improve treatment of Achilles tendon ruptures for female athletes.

Level of Evidence

Level IV, case series.

Auditing the Representation of Females Versus Males in Heat Adaptation Research

The aim of this audit was to quantify female representation in research on heat adaptation. Using a standardized audit tool, the PubMed database was searched for heat adaptation literature from inception to February 2023. Studies were included if they investigated heat adaptation among female and male adults (≥18-50 years) who were free from noncommunicable diseases, with heat adaptation the primary or secondary outcome of interest. The number and sex of participants, athletic caliber, menstrual status, research theme, journal impact factor, Altmetric score, Field-Weighted Citation Impact, and type of heat exposure were extracted. A total of 477 studies were identified in this audit, including 7,707 participants with ∼13% of these being female. Most studies investigated male-only cohorts (∼74%, n = 5,672 males), with ∼5% (n = 360 females) including female-only cohorts. Of the 126 studies that included females, only 10% provided some evidence of appropriate methodological control to account for ovarian hormone status, with no study meeting best-practice recommendations. Of the included female participants, 40% were able to be classified to an athletic caliber, with 67% of these being allocated to Tier 2 (i.e., trained/developmental) or below. Exercise heat acclimation was the dominant method of heat exposure (437 interventions), with 21 studies investigating sex differences in exercise heat acclimation interventions. We recommend that future research on heat adaptation in female participants use methodological approaches that consider the potential impact of sexual dimorphism on study outcomes to provide evidence-based guidelines for female athletes preparing for exercise or competition in hot conditions.

Cross-adaptation from heat stress to hypoxia: A systematic review and exploratory meta-analysis

Cross-adaptation (CA) refers to the successful induction of physiological adaptation under one environmental stressor (e.g., heat), to enable subsequent benefit in another (e.g., hypoxia). This systematic review and exploratory meta-analysis investigated the effect of heat acclimation (HA) on physiological, perceptual and physical performance outcome measures during rest, and submaximal and maximal intensity exercise in hypoxia. Database searches in Scopus and MEDLINE were performed. Studies were included when they met the Population, Intervention, Comparison, and Outcome criteria, were of English-language, peer-reviewed, full-text original articles, using human participants. Risk of bias and study quality were assessed using the COnsensus based Standards for the selection of health status Measurement INstruments checklist. Nine studies were included, totalling 79 participants (100 % recreationally trained males). The most common method of HA included fixed-intensity exercise comprising 9 ± 3 sessions, 89 ± 24-min in duration and occurred within 39 ± 2 °C and 32 ± 13 % relative humidity. CA induced a moderate, beneficial effect on physiological measures at rest (oxygen saturation: g = 0.60) and during submaximal exercise (heart rate: g = -0.65, core temperature: g = -0.68 and skin temperature: g = -0.72). A small effect was found for ventilation (g = 0.24) and performance measures (peak power: g = 0.32 and time trial time: g = -0.43) during maximal intensity exercise. No effect was observed for perceptual outcome measures. CA may be appropriate for individuals, such as occupational or military workers, whose access to altitude exposure prior to undertaking submaximal activity in hypoxic conditions is restricted. Methodological variances exist within the current literature, and females and well-trained individuals have yet to be investigated. Future research should focus on these cohorts and explore the mechanistic underpinnings of CA.

Sex differences in skeletal muscle fiber types: A meta-analysis

Biopsies have been acquired from living men and women to determine proportions of Type I (slow-twitch) and II (fast-twitch) skeletal muscle fibers since the 1970s. Sex differences have been assumed but the literature has not been submitted to meta-analysis. Here, the aim was to generate effect sizes of sex differences in muscle fiber cross-sectional areas, distribution percentages, and area percentages. Data from 2875 men and 2452 women, who participated in 110 studies, were analyzed. Myofibrillar adenosine triphosphatase histochemistry was used in 71.8% of studies to classify fibers as Type I, II, IIA, and/or IIX; immunohistochemistry, immunofluorescence, or sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used in 35.4% of studies to similarly classify myosin heavy chain (MHC) isoform content. Most studies involved biopsies from vastus lateralis (79.1%) in healthy individuals (92.7%) between 18 and 59 years old (80.9%). Men exhibited greater cross-sectional areas for all fiber types (g = 0.40-1.68); greater distribution percentages for Type II, MHC II, IIA, IIX fibers (g = 0.26-0.34); greater area percentages for Type II, IIA, MHC IIA, IIX fibers (g = 0.39-0.93); greater Type II/I and Type IIA/I fiber area ratios (g = 0.63, 0.94). Women exhibited greater Type I and MHC I distribution percentages (g = -0.13, -0.44); greater Type I and MHC I area percentages (g = -0.53, -0.69); greater Type I/II fiber area ratios (g = -1.24). These data, which represent the largest repository of comparative muscle fiber type data from living men and women, can inform discussions about biological sex and its impact on pathologies and sports performance (e.g., explaining sex differences in muscle strength and muscle endurance).

Use of Buffers in Specific Contexts: Highly Trained Female Athletes, Extreme Environments and Combined Buffering Agents-A Narrative Review

This narrative review evaluated the evidence for buffering agents (sodium bicarbonate, sodium citrate and beta-alanine), with specific consideration of three discrete scenarios: female athletes, extreme environments and combined buffering agents. Studies were screened according to exclusion and inclusion criteria and were analysed on three levels: (1) moderating variables (supplement dose and timing, and exercise test duration and intensity), (2) design factors (e.g., use of crossover or matched group study design, familiarisation trials) and (3) athlete-specific factors (recruitment of highly trained participants, buffering capacity and reported performance improvements). Only 19% of the included studies for the three buffering agents reported a performance benefit, and only 10% recruited highly trained athletes. This low transferability of research findings to athletes' real-world practices may be due to factors including the small number of sodium citrate studies in females (n = 2), no studies controlling for the menstrual cycle (MC) or menstrual status using methods described in recently established frameworks, and the limited number of beta-alanine studies using performance tests replicating real-world performance efforts (n = 3). We recommend further research into buffering agents in highly trained female athletes that control or account for the MC, studies that replicate the demands of athletes' heat and altitude camps, and investigations of highly trained athletes' use of combined buffering agents. In a practical context, we recommend developing evidence-based buffering protocols for individual athletes which feature co-supplementation with other evidence-based products, reduce the likelihood of side-effects, and optimise key moderating factors: supplement dose and timing, and exercise duration and intensity.

Factors Influencing the Hepcidin Response to Exercise: An Individual Participant Data Meta-analysis

BACKGROUND

Hepcidin, the master iron regulatory hormone, has been shown to peak 3-6 h postexercise, and is likely a major contributor to the prevalence of iron deficiency in athletes. Although multiple studies have investigated the hepcidin response to exercise, small sample sizes preclude the generalizability of current research findings.

OBJECTIVE

The aim of this individual participant data meta-analysis was to identify key factors influencing the hepcidin-exercise response.

METHODS

Following a systematic review of the literature, a one-stage meta-analysis with mixed-effects linear regression, using a stepwise approach to select the best-fit model, was employed.

RESULTS

We show that exercise is associated with a 1.5-2.5-fold increase in hepcidin concentrations, with pre-exercise hepcidin concentration accounting for ~ 44% of the variance in 3 h postexercise hepcidin concentration. Although collectively accounting for only a further ~ 3% of the variance, absolute 3 h postexercise hepcidin concentrations appear higher in males with lower cardiorespiratory fitness and higher pre-exercise ferritin levels. On the other hand, a greater magnitude of change between the pre- and 3 h postexercise hepcidin concentration was largely attributable to exercise duration (~ 44% variance) with a much smaller contribution from VO2max, pre-exercise ferritin, sex, and postexercise interleukin-6 (~ 6% combined). Although females tended to have a lower absolute 3 h postexercise hepcidin concentration [1.4 nmol·L-1, (95% CI [- 2.6, - 0.3]), p = 0.02] and 30% less change (95% CI [-54.4, - 5.1]), p = 0.02) than males, with different explanatory variables being significant between sexes, sample size discrepancies and individual study design biases preclude definitive conclusions.

CONCLUSION

Our analysis reveals the complex interplay of characteristics of both athlete and exercise session in the hepcidin response to exercise and highlights the need for further investigation into unaccounted-for mediating factors.

Underrepresentation of women in exercise science and physiology research is associated with authorship gender

Historically, low representation of women participants in exercise science and physiology studies has led to a lack of understanding in the response of women to exercise and therapeutic interventions. We hypothesized that 1) the number of women authors, participants, and editorial board members increased over 30 years (1991-2021) and 2) larger representation of women as editors and authors is associated with more women participants. Gender (man/woman) of editorial board members (n = 394), authors (n = 5,735), and participants (n = 2,984,883) of 972 original research articles with human participants published in 1991 and 2021 was analyzed from three journals: Journal of Applied Physiology, Medicine and Science in Sports and Exercise, and British Journal of Sports Medicine. Between 1991 to 2021, the average percent women per article as participants (21.9 ± 31.7% vs. 36.3 ± 30.3%, respectively, P < 0.001), authors (16.4 ± 22.4% vs. 30.9 ± 24.0%, P < 0.001), and editorial board members (13.3 ± 5.4% vs. 41.5 ± 7.3%, P = 0.006) increased. In 2021, the gender proportion of participants in large datasets was similar (50.2 ± 20.2% women). However, studies with smaller datasets (i.e., <∼3,000 participants) included less women (35.6 ± 30.6%). Women participants (%) were less when the last author was a man rather than a woman in 1991 (19.9 ± 29.5% vs. 34.3 ± 42.2%) and 2021 (31.6 ± 27.7% vs. 51.7 ± 33.4%). In 2021, there was a positive correlation between author and participant gender (% women) (r = 0.42, P < 0.001). Our data suggest that the low representation of women in exercise science and physiology research could be resolved with equitable numbers of women authors and editors and by encouraging men authors to study both women and men participants.NEW & NOTEWORTHY Analysis of human applied physiology studies revealed that the representation of women authors, participants, and editorial board members increased over 30 years but remained lower than men in 2021. Larger representation of women editors and authors was associated with more women participants. Women authors assessed similar numbers of women and men participants, whereas men authors included less women. Equitable representation of women participants may be achieved by closing the gender gap in authorship and editorial board membership.

On-Field Methodological Approach to Monitor the Menstrual Cycle and Hormonal Phases in Elite Female Athletes

OBJECTIVES

Currently, there are no guidelines for implementing the monitoring of menstrual status, including the natural menstrual cycle (NC) or oral contraception (OC), in a sport setting. We aimed to provide a feasible, on-field methodological approach for monitoring NC and OC in female athletes.

METHODS

We developed a smartphone app with daily questionnaires to monitor both NC and OC phases in 19 elite female soccer players (23.7 [4.4] y) over 7 months. Adherence and compliance were evaluated. The NC and OC phases were based on calendar data to establish an individual menstrual profile for each athlete.

RESULTS

The initial questionnaire revealed that the vast majority of female players (80%) were interested in monitoring their menstrual status. The online monitoring yielded high athlete adherence (87.0% [14.2%]) with a slight decrease over the winter break and at the end of the championship, which necessitated adaptations to promote compliance. Monitoring identified the specific menstrual pattern of each athlete and highlighted large interindividual variability.

CONCLUSION

This study assesses, for the first time, the interest of female players in monitoring their menstrual status. It provides a new methodological approach, as well as guidelines for optimizing on-field monitoring. It also anticipates some obstacles sport staff may encounter when trying to implement such follow-up. It is essential to better understand the menstrual profile of athletes and determine its potential impacts on well-being and performance.

Short Severe Energy Restriction with Refueling Reduces Body Mass without Altering Training-Associated Performance Improvement

PURPOSE

We investigated short-term (9 d) exposure to low energy availability (LEA) in elite endurance athletes during a block of intensified training on self-reported well-being, body composition, and performance.

METHODS

Twenty-three highly trained race walkers undertook an ~3-wk research-embedded training camp during which they undertook baseline testing and 6 d of high energy/carbohydrate (HCHO) availability (40 kcal·kg FFM -1 ·d -1 ) before being allocated to 9 d continuation of this diet ( n = 10 M, 2 F) or a significant decrease in energy availability to 15 kcal·kg FFM -1 ·d -1 (LEA: n = 10 M, 1 F). A real-world 10,000-m race walking event was undertaken before (baseline) and after (adaptation) these phases, with races being preceded by standardized carbohydrate fueling (8 g·kg body mass [BM] -1 for 24 h and 2 g·kg BM -1 prerace meal).

RESULTS

Dual-energy x-ray absorptiometry-assessed body composition showed BM loss (2.0 kg, P < 0.001), primarily due to a 1.6-kg fat mass reduction ( P < 0.001) in LEA, with smaller losses (BM = 0.9 kg, P = 0.008; fat mass = 0.9 kg, P < 0.001) in HCHO. The 76-item Recovery-Stress Questionnaire for Athletes, undertaken at the end of each dietary phase, showed significant diet-trial effects for overall stress ( P = 0.021), overall recovery ( P = 0.024), sport-specific stress ( P = 0.003), and sport-specific recovery ( P = 0.012). However, improvements in race performance were similar: 4.5% ± 4.1% and 3.5% ± 1.8% for HCHO and LEA, respectively ( P < 0.001). The relationship between changes in performance and prerace BM was not significant ( r = -0.08 [-0.49 to 0.35], P = 0.717).

CONCLUSIONS

A series of strategically timed but brief phases of substantially restricted energy availability might achieve ideal race weight as part of a long-term periodization of physique by high-performance athletes, but the relationship between BM, training quality, and performance in weight-dependent endurance sports is complicated.

Heat Adaptation for Females: A Systematic Review and Meta-Analysis of Physiological Adaptations and Exercise Performance in the Heat

BACKGROUND

Heat adaptation regimes are used to prepare athletes for exercise in hot conditions to limit a decrement in exercise performance. However, the heat adaptation literature mostly focuses on males, and consequently, current heat adaptation guidelines may not be optimal for females when accounting for the biological and phenotypical differences between sexes.

OBJECTIVES

We aimed to examine: (1) the effects of heat adaptation on physiological adaptations in females; (2) the impact of heat adaptation on performance test outcomes in the heat; and (3) the impact of various moderators, including duration (minutes and/or days), total heat dose (°C.min), exercise intensity (kcal.min-1), total energy expended (kcal), frequency of heat exposures and training status on the physiological adaptations in the heat.

METHODS

SPORTDiscus, MEDLINE Complete and Embase databases were searched to December 2022. Random-effects meta-analyses for resting and exercise core temperature, skin temperature, heart rate, sweat rate, plasma volume and performance tests in the heat were completed using Stata Statistical Software: Release 17. Sub-group meta-analyses were performed to explore the effect of duration, total heat dose, exercise intensity, total energy expended, frequency of heat exposure and training status on resting and exercise core temperature, skin temperature, heart rate and sweat rate. An explorative meta-regression was conducted to determine the effects of physiological adaptations on performance test outcomes in the heat following heat adaptation.

RESULTS

Thirty studies were included in the systematic review; 22 studies were meta-analysed. After heat adaptation, a reduction in resting core temperature (effect size [ES] =  - 0.45; 95% confidence interval [CI] - 0.69, - 0.22; p < 0.001), exercise core temperature (ES =  - 0.81; 95% CI - 1.01, - 0.60; p < 0.001), skin temperature (ES =  - 0.64; 95% CI - 0.79, - 0.48; p < 0.001), heart rate (ES =  - 0.60; 95% CI - 0.74, - 0.45; p < 0.001) and an increase in sweat rate (ES = 0.53; 95% CI 0.21, 0.85; p = 0.001) were identified in females. There was no change in plasma volume (ES = - 0.03; 95% CI - 0.31, 0.25; p = 0.835), whilst performance test outcomes were improved following heat adaptation (ES = 1.00; 95% CI 0.56, 1.45; p < 0.001). Across all moderators, physiological adaptations were more consistently observed following durations of 451-900 min and/or 8-14 days, exercise intensity ≥ 3.5 kcal.min-1, total energy expended ≥ 3038 kcal, consecutive (daily) frequency and total heat dose ≥ 23,000 °C.min. The magnitude of change in performance test outcomes in the heat was associated with a reduction in heart rate following heat adaptation (standardised mean difference =  - 10 beats.min-1; 95% CI - 19, - 1; p = 0.031).

CONCLUSIONS

Heat adaptation regimes induce physiological adaptations beneficial to thermoregulation and performance test outcomes in the heat in females. Sport coaches and applied sport practitioners can utilise the framework developed in this review to design and implement heat adaptation strategies for females.

Does Prematch Neuromuscular Performance Affect Running Performance in Collegiate Elite Female Soccer?

ABSTRACT

Ishida, A, Draper, G, White, JB, and Travis, SK. Does prematch neuromuscular performance affect running performance in collegiate elite female soccer? J Strength Cond Res 37(4): 854-858, 2023-The purpose of this study was to investigate whether prematch neuromuscular performance affected match physical performance by player position in Division I collegiate female soccer. Fourteen players participated (20.7 ± 1.3 years; 165.1 ± 6.0 cm; 63.3 ± 7.0 kg) in this study. Players were selected based on being free from injuries, playing for a duration of ≥72 minutes, and match intervals were ≥2 days. Data included 73 observations ( n = 5 defenders, n = 7 midfielders, and n = 2 forward) from 14 official matches. Prematch neuromuscular performance was assessed using countermovement jump (CMJ) with polyvinyl chloride pipe on dual force plates. Countermovement jump variables included jump height (JH) and relative peak power (RPP). Match physical performance included average speed, high-speed running (HSR), and number of high accelerations and decelerations. Linear mixed model was compiled with fixed effects of loaded with fixed effect of JH, RPP, and position and random effects per individual player. In CMJ and player position model, RPP was a significant predictor for average HSR ( p = 0.003) while fixed effects of JH and position were not significant ( p = 0.15-0.86). The fixed and random effects explained 34.8 and 42.1% of variances in average HSR. In CMJ-only model, RPP significantly predicted the variances in average HSR ( p = 0.001). The fixed effects and random effects of the model explained 22.7 and 51.8% of the variance in average HSR. However, position-only was not a significant predictor for average HSR in the position-only model ( p = 0.26 and 0.33). Prematch CMJ RPP may be the greatest predictor of average HSR in collegiate female soccer.

The sex gap in sports and exercise medicine research: who does research on females?

Females are underrepresented in sports and exercise medicine research, both as authors and as research participants. The aim of this study was therefore to explore who does sports and exercise medicine research on females. All original research articles with female-only samples published in six major sports and exercise medicine journals over a 7-year period (2014–2020; n = 334) were examined. Out of the 2027 authors of the articles in question, 1149 were categorized as male (56.7%) and 850 were categorized as female (41.9%; 28 [1.4%] could not be categorized). A slight majority of the articles had a female as first author (51.5%), while the majority of the last authors were male (62.3%). Binomial tests of proportions revealed that females were overrepresented in all author roles in this sample compared to the field at large, while chi-square tests of proportions indicated minimal variations in female authorship across the studied period. These findings indicate that females are relatively more likely to do research on females than males are, and that the rate of female authorship remained relatively constant over time.

Advancing feminist innovation in sport studies: A transdisciplinary dialogue on gender, health and wellbeing

Athlete health and wellbeing requires a holistic, multidimensional approach to understanding, supporting, and treating individual athletes. Building more supportive, inclusive, and equitable environments for the health and wellbeing of women and gender expansive people further requires gender-responsive approaches that promote broader cultural change. Feminist sport and exercise medicine practitioners, sports scientists, and social science researchers are increasingly coming together in their efforts to do this work. However, working across disciplines inevitably includes an array of ontological, epistemological, and political challenges. In this paper, we offer a curated 'dialogue' with a group of feminist scholars engaged in research and practice across disciplines, bringing them together to discuss some of the most pressing gendered issues in sport today (i.e., ACL injury, concussion, menstruation in sport, mental health, gender categories). In so doing, we amplify the voices of those working (empirically and clinically) at the disciplinary intersections of gender, sport and health, and learn about some of the current and future possibilities for transdisciplinary innovations and strategies for building (responsiveness to) cultural change.

Sex-Based Differences in Outcomes After Hip Arthroscopic Surgery for Femoroacetabular Impingement: A Systematic Review

BACKGROUND

While sex-based differences in outcomes after hip arthroscopic surgery for femoroacetabular impingement syndrome (FAIS) are often recorded, no studies have been dedicated to analyzing the literature as a whole.

PURPOSE

To investigate whether sex is a predictor of outcomes in studies evaluating hip arthroscopic surgery for FAIS.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We searched the PubMed, Embase, Cochrane, Ovid, and PubMed Central databases for English-language studies that evaluated sex-specific outcomes in human populations. The search terms used were as follows: ("Hip Arthroscopy") AND ("Femoroacetabular Impingement" OR "FAI") AND ("Sex" OR "Gender" OR "Male" OR "Female"). Studies with evidence levels 2 through 4 were included. The studies were then screened, followed by data extraction. Modified Harris Hip Score (mHHS) outcomes and return-to-sport (RTS) rates were recorded. These were analyzed using random-effects meta-analysis. Heterogeneity was calculated using the I ² statistic.

RESULTS

Of 256 full-text articles screened, 48 articles were included in this analysis; of these, 14 studies (29%) concluded that female sex was a negative predictor of postoperative outcomes, while 6 studies (13%) found female sex to be positive predictor. The remaining 28 studies (58%) found no sex-based differences in postoperative outcomes. Of 7 studies (416 male and 519 female) included in the mHHS analysis, 2 studies concluded that male patients had significantly higher postoperative mHHS scores. Of 6 studies (502 male and 396 female) included in the RTS analysis, 1 study concluded that male patients had a significantly higher RTS rate.

CONCLUSION

Almost one-third of the included studies determined that female sex was a negative predictor of postoperative outcomes, 13% found female sex to be a positive predictor, and 58% found no sex-based differences. Our study illustrates an insufficiency of high-level evidence supporting sex-specific differences in outcomes after hip arthroscopic surgery, but findings indicated that the postoperative mHHS score and RTS rate may be influenced by sex.

Dietary Inorganic Nitrate as an Ergogenic Aid: An Expert Consensus Derived via the Modified Delphi Technique

INTRODUCTION

Dietary inorganic nitrate is a popular nutritional supplement, which increases nitric oxide bioavailability and may improve exercise performance. Despite over a decade of research into the effects of dietary nitrate supplementation during exercise there is currently no expert consensus on how, when and for whom this compound could be recommended as an ergogenic aid. Moreover, there is no consensus on the safe administration of dietary nitrate as an ergogenic aid. This study aimed to address these research gaps.

METHODS

The modified Delphi technique was used to establish the views of 12 expert panel members on the use of dietary nitrate as an ergogenic aid. Over three iterative rounds (two via questionnaire and one via videoconferencing), the expert panel members voted on 222 statements relating to dietary nitrate as an ergogenic aid. Consensus was reached when > 80% of the panel provided the same answer (i.e. yes or no). Statements for which > 80% of the panel cast a vote of insufficient evidence were categorised as such and removed from further voting. These statements were subsequently used to identify directions for future research.

RESULTS

The 12 panel members contributed to voting in all three rounds. A total of 39 statements (17.6%) reached consensus across the three rounds (20 yes, 19 no). In round one, 21 statements reached consensus (11 yes, 10 no). In round two, seven further statements reached consensus (4 yes, 3 no). In round three, an additional 11 statements reached consensus (5 yes, 6 no). The panel agreed that there was insufficient evidence for 134 (60.4%) of the statements, and were unable to agree on the outcome of the remaining statements.

CONCLUSIONS

This study provides information on the current expert consensus on dietary nitrate, which may be of value to athletes, coaches, practitioners and researchers. The effects of dietary nitrate appear to be diminished in individuals with a higher aerobic fitness (peak oxygen consumption [V̇O2peak] > 60 ml/kg/min), and therefore, aerobic fitness should be taken into account when considering use of dietary nitrate as an ergogenic aid. It is recommended that athletes looking to benefit from dietary nitrate supplementation should consume 8-16 mmol nitrate acutely or 4-16 mmol/day nitrate chronically (with the final dose ingested 2-4 h pre-exercise) to maximise ergogenic effects, taking into consideration that, from a safety perspective, athletes may be best advised to increase their intake of nitrate via vegetables and vegetable juices. Acute nitrate supplementation up to ~ 16 mmol is believed to be safe, although the safety of chronic nitrate supplementation requires further investigation. The expert panel agreed that there was insufficient evidence for most of the appraised statements, highlighting the need for future research in this area.

Assessment of Exercise-Associated Gastrointestinal Perturbations in Research and Practical Settings: Methodological Concerns and Recommendations for Best Practice

Strenuous exercise is synonymous with disturbing gastrointestinal integrity and function, subsequently prompting systemic immune responses and exercise-associated gastrointestinal symptoms, a condition established as "exercise-induced gastrointestinal syndrome." When exercise stress and aligned exacerbation factors (i.e., extrinsic and intrinsic) are of substantial magnitude, these exercise-associated gastrointestinal perturbations can cause performance decrements and health implications of clinical significance. This potentially explains the exponential growth in exploratory, mechanistic, and interventional research in exercise gastroenterology to understand, accurately measure and interpret, and prevent or attenuate the performance debilitating and health consequences of exercise-induced gastrointestinal syndrome. Considering the recent advancement in exercise gastroenterology research, it has been highlighted that published literature in the area is consistently affected by substantial experimental limitations that may affect the accuracy of translating study outcomes into practical application/s and/or design of future research. This perspective methodological review attempts to highlight these concerns and provides guidance to improve the validity, reliability, and robustness of the next generation of exercise gastroenterology research. These methodological concerns include participant screening and description, exertional and exertional heat stress load, dietary control, hydration status, food and fluid provisions, circadian variation, biological sex differences, comprehensive assessment of established markers of exercise-induced gastrointestinal syndrome, validity of gastrointestinal symptoms assessment tool, and data reporting and presentation. Standardized experimental procedures are needed for the accurate interpretation of research findings, avoiding misinterpreted (e.g., pathological relevance of response magnitude) and overstated conclusions (e.g., clinical and practical relevance of intervention research outcomes), which will support more accurate translation into safe practice guidelines.

Managing Female Athlete Health: Auditing the Representation of Female versus Male Participants among Research in Supplements to Manage Diagnosed Micronutrient Issues

Micronutrient deficiencies and sub-optimal intakes among female athletes are a concern and are commonly prevented or treated with medical supplements. However, it is unclear how well women have been considered in the research underpinning current supplementation practices. We conducted an audit of the literature supporting the use of calcium, iron, and vitamin D. Of the 299 studies, including 25,171 participants, the majority (71%) of participants were women. Studies with exclusively female cohorts (37%) were also more prevalent than those examining males in isolation (31%). However, study designs considering divergent responses between sexes were sparse, accounting for 7% of the literature. Moreover, despite the abundance of female participants, the quality and quantity of the literature specific to female athletes was poor. Just 32% of studies including women defined menstrual status, while none implemented best-practice methodologies regarding ovarian hormonal control. Additionally, only 10% of studies included highly trained female athletes. Investigations of calcium supplementation were particularly lacking, with just two studies conducted in highly trained women. New research should focus on high-quality investigations specific to female athletes, alongside evaluating sex-based differences in the response to calcium, iron, and vitamin D, thus ensuring the specific needs of women have been considered in current protocols involving medical supplements.

Fluid Balance and Carbohydrate Intake of Elite Female Soccer Players during Training and Competition

This study examined sweat rate, sweat sodium concentration [Na⁺], and ad-libitum carbohydrate and fluid intakes in elite female soccer players during training (n = 19) and a match (n = 8); eight completed both for comparisons. Body mass (kg) was obtained before and after exercise to calculate sweat rate. The sweat [Na⁺] was determined from absorbent patches on the thigh or back. Sweat rate, percentage body mass change, and sweat [Na⁺] for 19 players during training were 0.47 ± 0.19 L·h⁻¹, +0.19 ± 0.65%, and 28 ± 10 mmol·L⁻¹, respectively. Sweat rate was higher during a match (0.98 ± 0.34 L·h⁻¹) versus training (0.49 ± 0.26 L·h⁻¹, p = 0.007). Body mass losses were greater post-match (−1.12 ± 0.86%) than training (+0.29 ± 0.34%, p = 0.003). Sweat [Na⁺] was similar for training (29 ± 9 mmol·L⁻¹) and a match (35 ± 9 mmol·L⁻¹) (p = 0.215). There were no differences in match versus training carbohydrate intakes (2.0 ± 2.3 g·h⁻¹, 0.9 ± 1.5 g·h⁻¹, respectively, p = 0.219) or fluid intakes (0.71 ± 0.30 L·h⁻¹, 0.53 ± 0.21 L·h⁻¹, respectively, p = 0.114). In conclusion, female soccer players’ sweat rates were higher during a match than during training, and carbohydrate intakes were below recommendations for matches and training.

A contemporary understanding of iron metabolism in active premenopausal females

Iron metabolism research in the past decade has identified menstrual blood loss as a key contributor to the prevalence of iron deficiency in premenopausal females. The reproductive hormones estrogen and progesterone influence iron regulation and contribute to variations in iron parameters throughout the menstrual cycle. Despite the high prevalence of iron deficiency in premenopausal females, scant research has investigated female-specific causes and treatments for iron deficiency. In this review, we provide a comprehensive discussion of factors that influence iron status in active premenopausal females, with a focus on the menstrual cycle. We also outline several practical guidelines for monitoring, diagnosing, and treating iron deficiency in premenopausal females. Finally, we highlight several areas for further research to enhance the understanding of iron metabolism in this at-risk population.

Gender Distribution Associated With the Journal Wilderness & Environmental Medicine

INTRODUCTION

Publication and peer review are fundamental to career advancement in science and academic medicine. Studies demonstrate that women are underrepresented in science publishing. We evaluated the gender distribution of contributors to Wilderness & Environmental Medicine (WEM) from 2010 through 2019.

METHODS

We extracted author data from ScienceDirect, reviewer data from the WEM Editorial Manager database, and editorial board data from journal records. Gender (female and male) was classified using automated probability-based assessment with Genderize.io software.

RESULTS

A total of 2297 unique authors were published over the 10-y span, generating 3613 authorships, of which gender was classified for 96% (n=3480). Women represented 26% (n=572) of all authors, which breaks down to 22% of all, 19% of first, 28% of second, and 18% of last authorships. Women represented 20% of peer reviewers (508/2517), 20% of reviewers-in-training (19/72), and 16% of editorial board members (7/45). The proportion of female authors, first authors, and reviewers increased over time. Women received fewer invitations per reviewer than men (mean 2.1 [95% CI 2.0-2.3] vs 2.4 [95% CI 2.3-2.5]; P=0.004), accepted reviews at similar rates (mean 73 vs 71%; P=0.214), and returned reviews 1.4 d later (mean 10.4 [CI 9.5-11.3] vs 9.0 d [95% CI 8.5-9.6]; P=0.005).

CONCLUSIONS

While female representation increased over the study period, women comprise a minority of WEM authors, peer reviewers, and editorial board members. Gender equity could be improved by identifying and eliminating barriers to participation, addressing any potential bias in review processes, implementing strategies to increase female-authored submissions, and increasing mentorship and training.

Auditing the Representation of Female Versus Male Athletes in Sports Science and Sports Medicine Research: Evidence-Based Performance Supplements

Although sports nutrition guidelines promote evidence-based practice, it is unclear whether women have been adequately included in the underpinning research. In view of the high usage rates of performance supplements by female athletes, we conducted a standardised audit of the literature supporting evidence-based products: β-alanine, caffeine, creatine, glycerol, nitrate/beetroot juice and sodium bicarbonate. Within 1826 studies totalling 34,889 participants, just 23% of participants were women, although 34% of studies included at least one woman. Across different supplements, 0–8% of studies investigated women exclusively, while fewer (0–2%) were specifically designed to compare sex-based responses. The annual publication of female-specific studies was ~8 times fewer than those investigating exclusively male cohorts. Interestingly, 15% of the female participants were classified as international/world-class athletes, compared with 7% of men. Most studies investigated performance outcomes but displayed poorer representation of women (16% of participants), whereas health-focussed studies had the greatest proportion of female participants (35%). Only 14% of studies including women attempted to define menstrual status, with only three studies (~0.5%) implementing best practice methodologies to assess menstrual status. New research should target the efficacy of performance supplements in female athletes, and future sports nutrition recommendations should specifically consider how well female athletes have contributed to the evidence-base.