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

Fit for comparison: controlling for cardiorespiratory fitness in exercise physiology studies of sex as a biological variable

More studies in exercise physiology are investigating sex as a biological variable, but the potential confounding effect of cardiorespiratory fitness is often neglected. As maximal oxygen uptake (V ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ ) correlates with many physiological outcomes at rest and in response to exercise, differences inV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ between male and female participants may hinder interpretation. Here we revisit decades-old arguments that advocate for matching males and females forV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ normalized to fat-free mass (FFM) when investigating sex differences in the context of exercise. The rationale for using FFM to normalizeV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ , as opposed to total body mass, is that females, on average, have a greater proportion of body fat than males and body fat does not contribute toV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ . Using a multistudy dataset of males (n = 54) and females (n = 54) matched forV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ per FFM, we illustrate the different approaches toV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ normalization and the effects of poor or incorrect matching on interpretation. Modern assessments of body composition allow for segregation of bone from total FFM and regional measures of body composition; however neither approach seems to be an improvement on whole-body FFM as the normalization factor forV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ . A group-level difference of less than 5% forV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ per unit FFM is a strong starting point for comparisons between males and females, but the allowable difference depends on the extent to which cardiorespiratory fitness influences the variable of interest and other competing study design decisions. Researchers should be encouraged to normalizeV ̇ O 2 max ${{\dot{V}}_{{{{\mathrm{O}}}_2}{\mathrm{max}}}}$ to FFM for exercise physiology studies investigating sex differences.

Dry Needling in Sports and Sport Recovery: A Systematic Review with an Evidence Gap Map

BACKGROUND

Dry needling is an increasingly popular technique used in sports and regenerative medicine contexts. However, there is no comprehensive overview of investigations of dry needling in sports and sport recovery.

OBJECTIVES

The objectives were to perform a systematic review of dry needling in sports athletes with an evidence gap map, to identify current gaps in the literature, and to provide stakeholders with direction for future research.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines were followed. Studies on healthy and injured athletes receiving dry needling were included. Three databases (PubMed, Scopus, and Web of Science) were searched, data were synthesized narratively, key data were summarized quantitatively, and an evidence gap map was created.

RESULTS

The authors incorporated 24 studies into the current study, encompassing 580 athletes, predominantly involving talent/developmental and highly trained/national-level athletes across 13 sports. Most studies used passive or placebo controls, with 37.5% incorporating active controls. Interventions focused mainly on the lower limbs (58.3%). Around 69% of studies reported pain perception outcomes, while six examined muscular strength, activity, and range of motion. While results varied, dry needling generally showed a more positive effect on pain than on athletic performance.

CONCLUSIONS

Dry needling studies seem to describe general effectiveness and safety for reducing pain and muscle stiffness in a wide variety of body regions. However, further research is needed on underrepresented populations such as elite, world-class, and Paralympic athletes, as well as expanding investigations into long-term effects and a broader range of muscle groups, particularly the hamstrings. The results may be valuable for medical professionals, sports medicine specialists, and researchers.

REGISTRATION

OSF project no.: osf.io osf.io/h3yeq.

Gender/sex differences: Representation of women in lateral ankle sprain research

BACKGROUND

Women have historically comprised lower percentages of sports science research participants compared to men. Lateral ankle sprains (LAS) are a common musculoskeletal injury that may affect women more than men.

OBJECTIVE

The primary purpose was to assess the representation of women participants in LAS research. The secondary purpose was to analyze the representation of women as authors in this same work.

DESIGN

Observational study.

SETTING

Systematic reviews on LAS in adults published between May 2013 and April 2023.

PARTICIPANTS

Eleven systematic reviews on LAS with 77 unique original research studies (10, 080 participants, 335 authors) met inclusion criteria.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The main outcomes were the proportion of women as participants and in author roles (primary, senior, and overall).

RESULTS

Women were underrepresented as participants (41%, n = 4150). Women were also the minority gender/sex for authors overall (26%, n = 86) as well as primary (32%, n = 23) and senior (29%, n = 19) authors. No clear increase in the inclusion of women as research participants was observed over time (p = .4), nor was there a significant increase in women authors (p = .1). A greater proportion of participants were women when the primary author was a woman (p = .008).

CONCLUSION

Women are underrepresented in LAS research overall, and there is a lack of clear progress in representation over time. Similarly, women are a minority of study authors and data suggest a possible temporal trend of improvement. Efforts should be made to increase the proportion of women included in LAS research in order to support equitable evidence-based care.

Could the perception of effort help us unravel the potential of "living low-training high"? A perspective article

Living low-training high may promote favourable physiological adaptations and improvement of exercise performance in normoxia following training at altitudes above 1500 m. Whether and how physiological adaptations to training high interact with the perception of effort remains unknown. This perspective article aims to carve out potential contributory effects of the perception of effort on performance changes following living low-training high interventions. It is based on two unique case reports, findings on known physiological adaptations to living low-training high, and integration of current knowledge on the neurophysiology of effort perception. Considering the current state of knowledge on the effect of exercising in hypoxia on perceived effort, we propose that the hypoxia exposure associated with living low-training high protocols interact with the perception of effort and its rating, by inducing adaptations that i) slow the development of neuromuscular fatigue and associated compensatory increase in motor command, ii) alter the functioning of the anterior cingulate cortex and/or the motor areas, and iii) alter the interaction with other psychological responses to the exercise. In the proposed framework using a psychophysiological approach, changes in the participants' report of their perceived effort would reflect underlying neurophysiological and psychological adaptations to hypoxia exposure.

Regulation of body temperature and blood pressure in women: Mechanisms and implications for heat illness risk

Increasing global temperatures due to ongoing climate change phenomena have resulted in increased risk of exertional heat illness in otherwise healthy, young individuals who work or play in the heat. With increasing participation of women in athletic, military and industrial activities that involve exertion in the heat, there is a growing need to study female physiology in this context. Mechanisms controlling blood pressure and body temperature have substantial overlap in humans, largely due to autonomic mechanisms which contribute to both. Similarly, illnesses that result from excessive heat exposure can often be traced back to imbalances in one or more of these autonomic mechanisms. In recent years, there has been increased recognition of the importance of sex as a biological variable for basic and applied research in these areas. The goal of this paper is to present an update on the integrative physiology and pathophysiology of responses to heat stress in women (thermoregulation and blood pressure regulation). In this context, it is often the case that differences between sexes are presented as 'advantages' and 'disadvantages' of one sex over the other. In our opinion, this is an over-simplification of the physiology which ignores the nuances and complexities of the integrative physiology of responses to heat exposure and exercise, and their relevance for practical outcomes.

Eight weeks of resistance exercise improves mood state and intestinal permeability in healthy adults: A randomized controlled trial

To explore a potential link between resistance exercise and the gut-brain axis, this study examined the impact of resistance exercise on intestinal permeability, as indicated by lipopolysaccharide binding protein (LBP), and mood state in healthy adults. Sedentary participants (n = 20; 39.5 ± 12.1 y; 27.4 ± 5.3 kg/m2) were randomly assigned to the resistance exercise (REX) or wait-listed control (CON) groups. REX participants strength trained 3× weekly (advancing from 45%-55% to 70%-80% 1RM for 3-4 sets over 8 weeks). Strength testing, evaluation of mood states, and collection of fasting blood occurred at baseline and weeks 4 and 8. At baseline, LBP concentrations were inversely correlated to all strength measures (r range: -0.48 to -0.57; p < 0.05). The gain in total strength [(split squat left + right)/2 + bench press] was 45% higher for REX versus CON participants (p = 0.019), and serum LBP concentrations fell 16% for REX participants and rose 9% in CON participants (p = 0.014). Mood was significantly improved by resistance training versus control (but this improvement was not related to changes in LBP; r = -0.001). These findings support a role for resistance exercise in improving mood state and intestinal barrier function, but more research is warranted to further explore the effects of resistance training on the gut-brain axis.

Does Creatine Supplementation Enhance Performance in Active Females? A Systematic Review

The use of creatine as a dietary supplement is widespread. However, its reported performance benefit has been largely demonstrated in male populations. The aim was to evaluate the effectiveness of creatine supplementation in improving exercise performance in active females. A secondary aim was to appraise the quality of research in this area. Five databases were searched from the earliest record to July 2024. Eligible studies used supplemental creatine as an intervention with physically active female participants and reported an exercise performance-related outcome. Study quality was appraised using the Critical Appraisal Skills Program randomised controlled trials checklist with four additional items related to methodological considerations for research with active females. Performance outcomes were categorised as strength/power, anaerobic, or aerobic. Of the 10,563 records identified, 27 studies were included. Participant calibre ranged from recreationally active to elite. Creatine interventions ranged from five days to 12 weeks and included a range of dosage strategies. Compared to placebo, 3/11 studies showed an improvement in strength/power outcomes, 4/17 showed an improvement in anaerobic outcomes, and 1/5 showed an improvement in aerobic outcomes. Study quality varied, but methodological considerations for research with female athletes were poorly addressed by most studies. Although some benefits were reported, most studies showed no improvement in performance compared to placebo. The heterogeneity in participant characteristics, performance tests, creatine intervention, insufficient consideration of the unique physiological characteristics of females, and an overall small evidence base limits our understanding of how creatine supplementation influences physical performance in active females.

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.

Effects of exercise on cAMP-mediated platelet inhibition in young women: a pilot study

PURPOSE

Exercise has been shown to reduce platelet reactivity and increase platelet sensitivity to prostacyclin, an endothelium-derived inhibitor of platelet activation, in middle-aged men and women. It is currently unknown if these beneficial effects can also be observed in young women and the intracellular mechanisms involved have not been identified. In this study, the feasibility of detecting changes in platelet reactivity, prostacyclin sensitivity and cAMP signalling were tested.

METHODS

10 well-trained and 10 sedentary but healthy young women participated in this study. Responses of washed platelets to thrombin receptor activating peptide 6, the thromboxane A2 receptor agonist U46619, and prostaglandin E1 were measured by light transmission aggregometry. Expression levels of proteins in the cAMP pathway including phosphorylation of the vasodilator-stimulated phosphoprotein were analysed by western blotting.

RESULTS

There was no evidence of reduced basal reactivity in platelets from the well-trained group (V ˙ O 2 max  = 51.1 ± 3.6 ml/kg/min) compared to the untrained group (V ˙ O 2 max  = 31.1 ± 4.7 ml/kg/min). Platelets from the trained group showed evidence of greater sensitivity to the anti-aggregatory effects of prostaglandin E1. The slope of the aggregation curves indicated an overall faster rate of aggregation in the untrained group. Mean phosphorylation levels of vasodilator-stimulating phosphoprotein were consistently higher in the trained group, indicative of increased protein kinase A activity.

CONCLUSION

Platelets from young women may exhibit an exercise-induced increase in sensitivity to prostacyclin leading to stimulation of the cAMP pathway. A larger study is warranted to explore this vasoprotective effect further.

Sex differences in human performance

Sex as a biological variable is an underappreciated aspect of biomedical research, with its importance emerging in more recent years. This review assesses the current understanding of sex differences in human physical performance. Males outperform females in many physical capacities because they are faster, stronger and more powerful, particularly after male puberty. This review highlights key sex differences in physiological and anatomical systems (generally conferred via sex steroids and puberty) that contribute to these sex differences in human physical performance. Specifically, we address the effects of the primary sex steroids that affect human physical development, discuss insight gained from an observational study of 'real-world data' and elite athletes, and highlight the key physiological mechanisms that contribute to sex differences in several aspects of physical performance. Physiological mechanisms discussed include those for the varying magnitude of the sex differences in performance involving: (1) absolute muscular strength and power; (2) fatigability of limb muscles as a measure of relative performance; and (3) maximal aerobic power and endurance. The profound sex-based differences in human performance involving strength, power, speed and endurance, and that are largely attributable to the direct and indirect effects of sex-steroid hormones, sex chromosomes and epigenetics, provide a scientific rationale and framework for policy decisions on sex-based categories in sports during puberty and adulthood. Finally, we highlight the sex bias and problem in human performance research of insufficient studies and information on females across many areas of biology and physiology, creating knowledge gaps and opportunities for high-impact studies.

Hormonal Basis of Biological Sex Differences in Human Athletic Performance

Biological sex is a primary determinant of athletic human performance involving strength, power, speed, and aerobic endurance and is more predictive of athletic performance than gender. This perspective article highlights 3 key medical and physiological insights related to recent evolving research into the sex differences in human physical performance: (1) sex and gender are not the same; (2) males and females exhibit profound differences in physical performance with males outperforming females in events and sports involving strength, power, speed, and aerobic endurance; (3) endogenous testosterone underpins sex differences in human physical performance with questions remaining on the roles of minipuberty in the sex differences in performance in prepubescent youth and the presence of the Y chromosome (SRY gene expression) in males, on athletic performance across all ages. Last, females are underrepresented as participants in biomedical research, which has led to a historical dearth of information on the mechanisms for sex differences in human physical performance and the capabilities of the female body. Collectively, greater effort and resources are needed to address the hormonal mechanisms for biological sex differences in human athletic performance before and after puberty.

No sex differences in oxygen uptake or extraction kinetics in the moderate or heavy exercise intensity domains

The integrative response to exercise differs between sexes, with oxidative energy contribution purported as a potential mechanism. The present study investigated whether this difference was evident in the kinetics of oxygen uptake (V̇o2) and extraction (HHb + Mb) during exercise. Sixteen adults (8 males, 8 females, age: 27 ± 5 yr) completed three experimental visits. Incremental exercise testing was performed to obtain lactate threshold and V̇o2peak. Subsequent visits involved three 6-min cycling bouts at 80% of lactate threshold and one 30-min bout at a work rate of 30% between the lactate threshold and power at V̇o2peak. Pulmonary gas exchange and near-infrared spectroscopy of the vastus lateralis were used to continuously sample V̇o2 and HHb + Mb, respectively. The phase II V̇o2 kinetics were quantified using monoexponential curves during moderate and heavy exercise. Slow component amplitudes were also quantified for the heavy-intensity domain. Relative V̇o2peak values were not different between sexes (P = 0.111). Males achieved ∼30% greater power outputs (P = 0.002). In the moderate- and heavy-intensity domains, the relative amplitude of the phase II transition was not different between sexes for V̇o2 (∼24 and ∼40% V̇o2peak, P ≥ 0.179) and HHb + Mb (∼20 and ∼32% ischemia, P ≥ 0.193). Similarly, there were no sex differences in the time constants for V̇o2 (∼28 s, P ≥ 0.385) or HHb + Mb (∼10 s, P ≥ 0.274). In the heavy-intensity domain, neither V̇o2 (P ≥ 0.686) or HHb + Mb (P ≥ 0.432) slow component amplitudes were different between sexes. The oxidative response to moderate- and heavy-intensity exercises did not differ between males and females, suggesting similar dynamic responses of oxidative metabolism during intensity-matched exercise.NEW & NOTEWORTHY This study demonstrated no sex differences in the oxidative response to moderate- and heavy-intensity cycling exercise. The change in oxygen uptake and deoxyhemoglobin were modeled with monoexponential curve fitting, which revealed no differences in the rate of oxidative energy provision between sexes. This provides insight into previously reported sex differences in the integrative response to exercise.