Methodological Recommendations for Menstrual Cycle Research in Sports and Exercise

The Effect of the Menstrual Cycle on Energy Intake: A Systematic Review and Meta-analysis

CONTEXT

Energy intake may differ across the menstrual cycle, with some studies identifying greater energy intake in the luteal phase (LP) compared with the follicular phase (FP) and others finding no clear differences. To date, no study has systematically synthesized the available data to draw more definite conclusions while considering any methodological inconsistencies between studies.

OBJECTIVE

The aim was to conduct a systematic review/meta-analysis in an effort to determine if there are differences in energy intake between the FP and LP.

DATA SOURCES

A systematic search strategy was developed and the search was conducted in 5 databases for studies that investigated any changes in energy intake across menstrual phases.

DATA EXTRACTION

Using Covidence, studies were identified and included if they contained individuals between the ages of 18 and 45 years, maintained an average body mass index (BMI) of 18.5-25 kg/m2, had no history of disordered eating, and included energy intake and menstrual cycle measurements in the FP and LP.

DATA ANALYSIS

Effect sizes were calculated for each study and a random-effects model was used to pool the results of each study.

RESULTS

Fifteen datasets were included consisting of 330 female participants with a mean age of 26 ± 4 years and mean BMI of 22.4 ± 2.3 kg/m2. Overall, there was a statistically significant difference (standardized mean difference = 0.69; P = .039) with increased energy intake in the LP compared with the FP (crude 168 kcal⋅d-1 average difference between phases).

CONCLUSION

Energy intake was found to be greater in the LP compared with the FP, providing insight into the effect of the menstrual cycle on energy intake. However, there were repeated methodological inconsistencies and future work should strive to utilize best practices for both energy intake measurement and menstrual phase specification.

Test-retest reliability of TMS motor evoked responses and silent periods during explosive voluntary isometric contractions

PURPOSE

This study assessed the test-retest reliability of TMS motor evoked potentials (MEPs) and silent periods at early, middle, and late phases of the rising time-torque curve during explosive voluntary contractions. We also investigated how the number of consecutively averaged measurements influenced reliability.

METHODS

On two separate occasions 3-7 days apart, 14 adults performed several isometric explosive (1-s) contractions of the knee extensors, some of which were superimposed with TMS to elicit MEPs in the superficial quadriceps. Of those with TMS, stimulation was timed to elicit MEPs at either 45 (early), 115 (middle), or 190 ms (late) following contraction onset (16 with-TMS contractions per time condition). TMS was also superimposed at the plateau of 15 separate MVCs. Test-retest intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for MEPs and silent periods consecutively averaged over 3 to 15 separate contractions.

RESULTS

No one condition/phase was more reliable than another. For MEP amplitude, in all conditions except the explosive late phase, ICCs generally increased, and CV decreased, with an increase in the number of averaged contractions, and were > 0.50 ICC and < 15% CV within seven contractions. For silent period, ICCs and CVs were unaffected by the number of consecutively averaged contractions and remained > 0.50 ICC and < 10% CV.

CONCLUSION

Test-retest reliability of TMS responses is comparable between phases of explosive contraction and at the plateau of MVC. To maximise reliability of MEPs during explosive contractions or MVCs, we recommend future studies average data across more than the 3-5 contractions typically reported in the literature investigating MEPs at MVC plateau.

Impact of BRACTS exercises on muscular strength in eumenorrheic women

The sex steroid hormones significantly impact women's physiology. Therefore, recently developed integrated exercises consisting of Bending, Roll-ups, Arm swings with loads, Crunches, Tandem walks, and Squats (BRACTS) were formulated. It was the exercise approach that required minimal equipment and was cost-effective and practical for implementation across a broad spectrum of women. So, this study aims to evaluate the effects of BRACTS exercises on strength during different phases of the menstrual cycle in eumenorrheic women. This is a two-armed parallel design, single-blinded, randomized controlled trial following Consolidated Standards of Reporting Trials (CONSORT) guidelines, and the study protocol is based on Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines. Participants were randomly allocated with a 1:1 ratio into Group A (control group) and Group B (treatment group). Group A was given an educational program related to menstrual hygiene and active lifestyle maintenance with 20 min walk 3 times a week for 16 weeks, while group B was given an educational program related to menstrual hygiene along with BRACTS exercises of 50 min for 3 times per week for 16 weeks. Assessments were done at baseline, midline, and end of the therapy using SPSS version 25. The experimental group demonstrated a notable improvement in muscular strength in follicular, mid-cycle, and luteal phases, with Cohen's d values for left and right hand grip strength to be maximum in follicular phase while for left and right quadriceps, left and gastro-soleus showed maximum Cohen's d value in mid-cycle phase of menstrual cycle. The mixed model ANOVA indicates statistically significant differences (p < 0.05) between the two groups, with influence from menstrual cycle phases. So, the BRACTS exercise protocol significantly improves muscular strength across different phases of the menstrual cycle in eumenorrheic women, demonstrating its efficacy as a cost-effective and practical approach. The trial was registered on clinicaltrials.gov for registration with ID: NCT05460741 on 05/31/2022 and was last released on 04/29/2024.Trial registration number: NCT05460741.

Effect of caffeine supplementation on physical performance in a 5 km cycling time trial of healthy young adult women in different phases of the menstrual cycle: A parallel, randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Although caffeine is the most studied ergogenic aid, few studies have been conducted to evaluate the effect of caffeine supplementation among women in different phases of the menstrual cycle (MC).

AIM

To verify the effect of caffeine supplementation and the MC phase on the performance of a 5 km cycling time trial of female exercise practitioners (FEP).

METHODS

This was a parallel, double-blind, randomized, placebo-controlled clinical trial with a sample of women aged 18-35 years, all with regular MC. The caffeine (CAFG) and placebo (PLAG) groups performed the exercise test during the late follicular phase and mid-luteal phase. These time points were individually assessed according to each woman's MC. On the test day, they were instructed to intake a standardized meal. Subsequently, 30 min following the meal, volunteers consumed caffeine (6 mg·kg-1) or placebo. One hour following caffeine intake, the exercise protocol started. The participants were instructed to perform an all-out 5-km cycling time trial.

RESULTS

Twenty-one women with a mean age of 26.6 years (PLAG, n = 10; 26.7 y; CAFG, n = 11; 26.5 y) were evaluated. The mean test duration was approximately 10-min, with no effect of the MC phase (F = 0.410; p = 0.532), caffeine supplementation (F = 2.23; p = 0.156), or interaction (F = 0.298; p = 0.593). Likewise, we did not verify the effect of the MC phase (F = 0.249; p = 0.625), caffeine supplementation (F = 2.35; p = 0.146), or interaction (F = 0.585; p = 0.456) on the mean power.

CONCLUSION

Neither caffeine supplementation nor the different MC phases had an impact on the 5-km cycling TT performance of FEP.

Using environmental and exercise physiology to address gender inequalities in climate change and occupational health research

Climate change is a health-risk and health-inequity multiplier with excessive heat exposure a direct climate change impact already affecting the health and livelihood of billions globally. Women face greater risks and burdens from climate change impacts. Biological sex may or may not influence an individual's thermoregulatory capacity, heat tolerance or heat susceptibility. However at a population level, sex differences in physiological characteristics (anthropometrics, aerobic capacity, etc.) likely affect thermoregulatory capacity. Still, gender appears to play the most significant role in heat exposure and resulting health impacts. For climate change resilience and adaptation strategies to be effective, public health and occupational guidance/governance must be based on comprehensive and representative evidence. The current dearth of empirical evidence on how excessive heat exposure affects women prohibits this. Environmental and exercise physiology can help address this lack of empirical evidence by adhering to inclusive research guidelines. This paper is based on a symposium presentation given at Physiology 2023 in Harrogate, UK. Using a multi-year cohort study on industrial agricultural workers (the Adelante Initiative) as a case study, this review discusses the role of environmental and exercise physiology in generating inclusive research and evidence to inform occupational and public health guidance/governance for climate change resilience and adaptation, specifically heat exposure.

No sex differences in systemic metabolic responses to acute sprint interval training performed after an oral 75-g glucose load in adults with excess adiposity

BACKGROUND & AIMS

Research exploring sex-based variations in responses to acute sprint interval training (SIT) remains limited. This study aimed to examine the impact of biological sex on the systemic metabolic response to SIT. We hypothesized that acute metabolic responses to SIT would differ between males and females.

METHODS

Sedentary adults (15 males; 14 females) with excess adiposity (defined as body fat >30 %) were matched for age (32.8 ± 7.5 vs. 29.5 ± 6.5 years) and body fat mass (33.0 ± 2.9 vs. 33.2 ± 2.8 %). Following a 75-g glucose load, participants were randomly allocated to either a control (resting) or SIT trial (8 × 30 s of "all-out" cycling at a resistance of 0.075 % W kg-1 of muscle mass, interspersed with 1 min of recovery). Parameters assessed included respiratory quotient (RQ), resting energy expenditure (REE), substrate utilization rates (fat and carbohydrate), total energy output, and blood lactate and glucose levels. These were collected during fasting and at 60, 120, and 240 min post-glucose load, with the area under the curve (AUC) calculated for both trials.

RESULTS

An interaction was observed in time (P = 0.012) and trial (P < 0.001) for RQ; however, there was no significant interaction between sex × trial (P = 0.818). Males exhibited higher mean REE values than females in both conditions. Nevertheless, AUC analysis showed no significant interaction between sex and trial (P = 0.562). A significant trial × time relationship was found for fat and carbohydrate percentage contributions (P < 0.001). Post-SIT, AUCs for fat contribution (g min-1 and mg kg-1 min-1) to energy expenditure increased in both sexes compared with resting (P < 0.05), with differences noted among trials over time (P < 0.001). Blood lactate levels also increased similarly post-SIT in both sexes (P < 0.05), without a significant sex × trial interaction (AUC, P = 0.798).

CONCLUSIONS

These data demonstrate that exercise differed between the sexes and did not support the premise that acute metabolic responses to SIT would vary between males and females.

Best practices for including sex as a variable in appetite research

Despite increasing recognition that sex is a critical variable in appetite research, many studies fail to include participants of both sexes, fail to consider reproductive physiology in participant selection, or include both sexes but fail to test for sex differences in outcomes. To help remedy this situation, this article seeks to engender enthusiasm for including sex as a variable in appetite research. We first illustrate some sex differences in healthy and disordered eating, including both male-female differences and differences across the menstrual cycle. We next provide methodological guidance for studies involving male and female participants around puberty, during reproductive adulthood, and during reproductive senescence. Studies in children ≥5 y of age should consider adrenarche and gonadarche. Appetite studies in girls and women following menarche and similarly aged males should consider the influences of sex-specific aspects the hypothalamic-pituitary-gonadal (HPG) axis function. The cyclicity of HPG function (i.e., the menstrual cycle) in girls and women presents the challenge of identifying of menstrual-cycle subphases, which are highly variable within and between individuals. Reproductive senescence refers to changes in HPG axis function that occur in both men and women beginning in mid-life. Current best practices involve consideration of hormone-assay methodology, experimental design, and statistical analyses. On the horizon are options based on wearable-sensors and nanotechnology. Well informed consideration of sex as a variable will accelerate progress in appetite research by increasing rigor, replicability, and relevance.

Dribble deficit as an effective measure of dribbling ability independent of sprinting performance in professional female handball players

Purpose

The purpose of this study was to determine the relationship between linear and change-of-direction sprinting performance with dribbling performance and Dribble Deficit in professional female handball players.

Methods

Eleven professional female handball players (mean age: 21.12 ± 4.34 years; body height: 171.59 ± 4.52 cm; body weight: 66.29 ± 5.73 kg) participated in the study. Each participant completed several linear (sprint over 10, 20, and 30 m) and change-of-direction tests (slalom test, zig-zag test, 505 test), first without the ball (sprinting performance) followed by ball dribbling (dribbling performance). Dribble Deficit was calculated indirectly as the time difference between the best trial while dribbling minus the best trial without dribbling.

Results

A large to very large correlation was observed between the linear sprint and dribbling performance (r = 0.53-0.78), as well as between change-of-direction sprinting performance and dribbling performance (r = 0.66-0.88). The study also showed a moderate to perfect relationship between linear dribbling performance and Dribble Deficit (r = 0.46-0.93), and a large relationship between change-of-direction dribbling performance and Dribble Deficit (r = 0.54-0.55), while the relationships between linear sprinting performance and Dribble Deficit (r = -0.51-0.21) and between change-of-direction sprinting performance and Dribble Deficit (r = -0.14-0.26) were small and non-significant.

Conclusion

In summary, Dribble Deficit reflects dribbling ability independent of sprinting ability and refines its application for practical use in assessing dribbling skills in female handball players.

No Differences in Lactate Threshold Across the Menstrual Cycle in Untrained Females

In addition to maximal oxygen consumption (VO2max), the Lactate Threshold (LT) is the other major determinant of aerobic exercise performance. This study examined the effects of the menstrual cycle (MC) phase on the LT in untrained females. Eight females and 8 males completed a LT test on a cycle ergometer. The tests were performed across three MC phases: early follicular (EF; menses), ovulatory (O), and mid-luteal (ML). The male participants (control group) were randomly assigned visits at similar time intervals as a regular 28-day cycle. Blood lactate was obtained during the last minute of each 3-minute stage of the LT test. The LT was determined by visual method (LTvis), and fixed blood lactate concentrations of 2.0 mmol/L (LT2.0mmol) and 4.0 mmol/L (LT4.0mmol). There were no statistically significant differences in power at LT for any of the determination methods across the MC for the female participants (p>0.05) or across the time intervals for the male participants (p>0.05). The male participants tended to have higher power at LT for all three methods LTvis (41.91W), LT2.0mmol (44.68W), and LT4.0mmol (55.94W). These findings support that the MC does not seem to influence power at LT in untrained naturally menstruating females.

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.

Repeated Sprint Variations According to Circadian Rhythm at Different Menstrual Cycle Phases

This study assessed the repeated sprint performance in relation to circadian rhythm during different menstrual cycle phases (MCP). Twelve volunteer eumenorrheic women team sport athletes performed 5×6-s cycling sprints in morning (9 am to 10 am) and evening (6 pm to 7 pm) sessions during the mid-follicular (FP, 6th-10th d) and luteal phases (LP, 19th-24th d). Body weight, oral body temperature, resting heart rate and lactate levels together with estradiol, progesterone and cortisol levels were determined before tests. Relative peak and mean power and performance decrements were determined as performance variables and maximum heart rate, lactate and ratings of perceived exertion were determined as physiological variables. Evening body temperatures were significantly higher. Cortisol levels were higher in the morning and in the FP. Resting lactate levels did not vary with MCP or time of day, but a significant MCP x time of day interaction was observed. Body weight showed no change according to time of day and MCP. There was no significant effect of MCP and time of day on performance and physiological variables, in contrast, maximum lactate values were notably higher in the evening. In conclusion, MCP and time of day need not be considered during repeated sprint exercises of eumenorrheic women athletes.

Development and evaluation of an ovarian hormone profile classification tool for female athletes: step one of a two-step process to determine ovarian hormone profiles

Objective

This study aimed to develop a reliable, comprehensive and fit-for-purpose tool for classifying ovarian hormone profiles (OHPs) (step one of a two-step process) in postmenarcheal to perimenopausal female athletes.

Methods

The OHP classification tool was designed by a team of sport scientists, practitioners and medics and is intended for use by sport practitioners. It incorporates self-reported data and guides subsequent verification methods. Written feedback was received from practitioners currently working with elite female athletes (n=5), ensuring its applicability in an applied sport setting. In addition, inter-user (n=2) and intra-user (n=30) repeatability was assessed.

Results

All practitioners agreed that the online tool was user-friendly. Four (out of five) practitioners stated they would include the tool in their practice, with the fifth stating that they did not have the capacity to incorporate it in their practice at present. The OHP classification tool showed excellent test-retest reliability with Cronbach's alpha values exceeding 0.9.

Conclusion

This tool facilitates the classification of OHPs and promotes discussions between athletes and practitioners, enhancing understanding and management of ovarian hormone health in sportswomen.

The effects of inorganic nitrate supplementation on muscular power and endurance across the menstrual cycle

Oral inorganic nitrate ([Formula: see text]) supplementation increases nitric oxide (NO) bioavailability and may improve muscular power in males and females, although data in females are limited. Estrogen increases NO bioavailability and fluctuates throughout the menstrual cycle, with low levels in the early follicular (EF) phase and peaking during the late follicular (LF) phase. The purpose of the present study was to examine the effects of [Formula: see text] supplementation on isokinetic peak power, maximal voluntary isometric contraction (MVIC) force, muscular endurance, and recovery from fatigue in healthy young females during the EF and LF phases of the menstrual cycle. Ten eumenorrheic females were tested in a double-blinded, randomized, placebo-controlled design. Participants consumed ∼13 mmol [Formula: see text], in the form of 140 mL beetroot juice (BRJ), or an identical [Formula: see text]-depleted placebo (PL), for ∼5 days prior to visits and 2 h prior to testing. Plasma estradiol was elevated in the LF phase, and plasma nitrite and nitrate were elevated in the BRJ condition (P < 0.05). Although isokinetic peak power was unchanged, calculated maximal power (Pmax) and maximal velocity (Vmax) were significantly worsened in the BRJ treatment independent of the menstrual cycle phase (P = 0.02 and 0.03, respectively). Muscular endurance, MVIC, and fatigue recovery were unaltered by BRJ or the menstrual cycle. These data indicate that [Formula: see text] supplementation decreased maximal power and velocity in females and suggest that the benefits of [Formula: see text] supplementation previously found in males may not extend to young females.NEW & NOTEWORTHY Recent data have suggested that inorganic nitrate ([Formula: see text]) supplementation may benefit males, however, females may experience worsened endurance capacity independent of menstrual cycle phase. This study revealed neither [Formula: see text] supplementation nor the follicular phase of the menstrual cycle influenced maximal isometric voluntary contraction or endurance capacity in healthy, young, naturally menstruating females, whereas [Formula: see text] supplementation significantly worsened estimated peak power (Pmax) and velocity (Vmax) independent of the menstrual cycle phase.

The influence of a vegan diet on body composition, performance and the menstrual cycle in young, recreationally trained women- a 12-week controlled trial

BACKGROUND

An increasing number of people, including recreational trained individuals, choose not to consume animal products and follow a vegan diet. Young women in particular are switching to a vegan diet. Studies have shown no difference in performance and muscle adaptations between a balanced vegan and an omnivorous diet. However, there are hardly any studies on the transition phase from an omnivorous to a vegan diet and the potential difficulties. Therefore, this study aimed to investigate the influence of a vegan dietary transition and its effects on body composition, physical performance, and menstrual cycle in young, recreationally trained women.

METHODS

Ten young healthy women (23.8 ± 2.0 years, 173.0 ± 5.8 cm) were recruited to participate in this 12-week controlled study (4-week omnivorous phase, 8-week vegan intervention). At the beginning and before the vegan phase, all participants were informed about a balanced diet for fitness-oriented individuals and a vegan lifestyle. They were supervised by a sports dietitian for the entire 12 weeks. Explicit instructions and regular checks on macronutrient distribution were not carried out but had to be implemented independently. The diet was documented using FDDB Extender. The training habits were not explicitly specified, but should not be changed over the entire period. At baseline (T0) and 4-week intervals (T1, T2, T3), body composition (body weight, skeletal muscle mass, fat mass) and performance (squat, countermovement jump) were tested. In addition, the menstrual cycle was examined every two days using saliva samples and a cycle diary.

RESULTS

Between treatments, there was a significant decrease in absolute (T0: 94.44 ± 20.37 kcal; T3: 71.67 ± 27.64 kcal; p < 0.001) and in relative protein intake (T0: 1.39 ± 0.28 g/kg BW; T3: 1.06 ± 0.37 g/kg BW; p < 0.05). In carbohydrate consumption, a significant increase was observed (T0: 240.11 ± 53.15 kcal; T3: 266.89 ± 49.01 kcal; p < 0.001). During the vegan phase, a significant decrease in body weight (T0: 68.19 ± 6.47 kg, T3: 67.73 ± 6.07 kg; p < 0.001) and skeletal muscle mass (T0: 29.40 ± 2.23 kg; T3: 28.74 ± 2.55 kg; p < 0.001) was observed. No changes were noted in squat performance. The countermovement jump showed a significant decrease in the vegan phase (T0: 26.08 ± 3.44 cm; T3: 23,62 ± 1,00 p < 0.05), but also a significant time effect starting in the omnivorous phase (p < 0.001). No effects were found on hormone concentrations of individual menstrual cycles.

CONCLUSION

The dietary change resulted in a shift in overall macronutrient distribution. Relative protein intake was significantly lower during the vegan phase than during the omnivore phase. This was also observed in a slight decrease in skeletal muscle mass. No clear effects on performance and menstrual cycle were observed during the first eight weeks. The results suggest that despite the knowledge of a balanced diet and in particular the recommendations for a vegan diet, the implementation of a vegan diet in everyday life could be associated with a number of difficulties for recreationally trained women. However, it should be noted that the vegan phase was only conducted for eight weeks and no statement can be made about the long-term effects or on well-trained female athletes.

Study on the correlation between energy availability and subclinical menstrual disorders

Background

There are few studies on the correlation between energy availability (EA) and subclinical menstrual disorders (SMD) in female athletes. This study aims to explore the differences in EA between female athletes with eumenorrhea and those with SMD, and the correlation between EA and the occurrence of SMD.

Methods

Luteal phase defect (LPD) and anovulation were defined as SMD. Fifty-six adult female college athletes with regular menstrual cycles and no clinical symptoms of menstrual disorders (MD) were selected as subjects. The EA of the subjects was monitored, and SMD were identified. The EA was compared between the two groups, and the correlation between EA and the occurrence of SMD was analyzed.

Results

Nineteen subjects were identified as LPD, and 7 subjects were identified as anovulation. The occurrence of SMD was 46.4%. The EA of subjects with SMD was lower than that of subjects with eumenorrhea (t = 3.165, p = 0.003), and EA was negatively correlated with the occurrence of SMD (r = -0.396, p = 0.000).

Conclusion

There were differences in EA between female college athletes with eumenorrhea and SMD. EA was negatively correlated with the occurrence of SMD.

Effect of menstrual cycle phase on physiological responses in healthy women at rest and during submaximal exercise at high altitude

As more women engage in high-altitude activities, understanding how ovarian hormone fluctuations affect their cardiorespiratory system is essential for optimizing acclimatization to these environments. This study investigates the effects of menstrual cycle (MC) phases on physiological responses at rest, during and after submaximal exercise, at high-altitude (barometric pressure 509 ± 6 mmHg; partial pressure of inspired oxygen 96 ± 1 mmHg; ambient temperature 21 ± 2 °C and relative humidity 27 ± 4%) in 16 eumenorrheic women. Gas exchange, hemodynamic responses, heart rate variability and heart rate recovery (HRR) were monitored at low altitude, and then at 3375 m on the Mont Blanc (following nocturnal exposure) during both the early-follicular (EF) and mid-luteal (ML) phases. Significant differences were observed between low and high-altitude in ventilation, heart rate and cardiac output. Resting ventilation (15.2 ± 1.9 vs. 13.2 ± 2.5 L.min-1; p = 0.039) and tidal volume (812 ± 217 vs. 713 ± 190 mL; p = 0.027) were higher during EF than ML at high-altitude. These differences between EF and ML were no longer evident during exercise, with comparable responses in oxygen uptake kinetics, cycling efficiency and HRR. The MC had negligible effects on physiological responses to high-altitude. An individualized approach, tailored to each woman's specific responses to hypoxia across the MC, may be more beneficial in optimizing high-altitude sojourns than general guidelines.

Original salivary sex hormone data of naturally menstruating athletes and hormonal contraceptive users

Objectives

There is a lack of data on salivary sex hormones across the menstrual cycle (MC) or hormonal contraceptive (HC) cycle of elite athletes. We aimed to provide original data on salivary sex hormones (17β-estradiol, progesterone and free testosterone) in naturally menstruating female athletes with a regular cycle or irregular cycle and using combined HC. A secondary purpose was to compare these data with published data from the general population according to the menstrual status (MC or HC or irregularly menstruating).

Methods

367 saliva tests were performed on 44 elite athletes during 6 months of follow-up to certify for cycle regularity. Athletes were grouped into regular MC, n=13; irregular MC, n=5; and HC, n=26. We compared salivary data of regular MC across six cycle phases (menses, mid-follicular, late follicular, early luteal, mid-luteal and late luteal phases) with published data from women with a similar MC or HC status from the general population.

Results

We provided salivary original data according to six sub-phases among elite athletes with regular MC. HC athletes showed lower salivary sex hormonal levels, markedly after the first week of active HC compared with regular MC. Athletes with irregular cycles do not show a progesterone rise from the first half to the second half of the cycle (Δirregular=0.38 (1.90), a rise detectable within regular MC group ΔregularMC=2.86 (2.88)).

Conclusions

We provided original data for salivary sex hormone levels in elite female athletes. These references may be valuable for research investigating MC or combined HC data, particularly in longitudinal follow-ups requiring repeated measurements.

The effect of the menstrual cycle phases on back squat performance, jumping ability and psychological state in women according to their level of performance -a randomized three-arm crossover study

OBJECTIVE

The influence of the menstrual cycle on practical power performance such as barbell back squats and jumping performance in women has not yet been fully investigated. In addition, the performance level of athletes has not been considered in previous studies. This study aimed to investigate the influence of different cycle phases on acute back squat performance, jumping ability and psychological state concerning the performance level.

METHODS

24 female strength athletes (age: 25.2 ± 3.3 years; height: 169.5 ± 3.4 cm; body weight: 67.7 ± 7.3 kg) were recruited for the study. Level of performance was classified according to Santos et al. (intermittent (n = 13), advanced (n = 6), highly advanced (n = 5)). Participants were tested for 1RM barbell back squat and jumping performance (countermovement and squat jump) as well as two questionnaires assessing their psychological states in the menses (M), late follicular phase (FP) and mid-luteal phase (LP) in three MC. Saliva estradiol and progesterone concentrations with a menstrual cycle diary were used to confirm a normal MC. A principal components analysis for power performance, well-being, relaxation and alertness was carried out and a linear mixed model was used for statistical evaluation.

RESULTS

No significant differences were found between the MC phases in performance scores (p > 0.05), readiness (p > 0.05) and alertness (p > 0.05). However, a high correlation between MC phases, performance level and back squat performance was detected. Correlation analyses indicate that a higher performance level results in a higher variation depending on the MC of the squat performance. For well-being, a significantly lower score was detected in M than in FP and LP.

CONCLUSION

In general the performance score of the lower body is not influenced by the MC. If strength performance and jumping ability are considered separately, there are indications that strength capability is influenced at a higher performance level. In addition, individual variance was also observed, so this should also be considered. However, further studies are needed to confirm this assumption due to the small sample sizes of the individual performance levels.

TRIAL REGISTRATION

German registry for clinical studies (DRKS00034816, Date: 08/01/2024).

Polarized running training adapted to versus contrary to the menstrual cycle phases has similar effects on endurance performance and cardiovascular parameters

PURPOSE

This study compared the effects of polarized running training adapted to the menstrual cycle (MC) phases versus polarized training adapted contrary to the MC on endurance performance and cardiovascular parameters.

METHODS

Thirty-three naturally menstruating, moderately trained females (age: 26 ± 4 years; BMI: 22.3 ± 3.2 kg/m2; V ˙ O2max/rel: 40.35 ± 4.61 ml/min/kg) were randomly assigned to a control (CON) and intervention (INT) group. Both groups participated in a load-matched eight-week running training intervention. In the INT, high-intensity sessions were aligned with the mid and late follicular phase, low-intensity sessions with the early and mid-luteal phase, and recovery with the late luteal and early follicular phase. In the CON, high-intensity sessions were matched to the late luteal and early follicular phase, and recovery to the mid and late follicular phase. Endurance performance and cardiovascular parameters were assessed at baseline and after the intervention.

RESULTS

Twenty-six females completed the intervention. A repeated measures ANOVA determined no time × group interaction effect for any parameter. A significant time effect was found for maximal oxygen uptake (F(1,12) = 18.753, p = 0.005, ηp2 = 0.630), the velocity at the ventilatory threshold one (F(1,12) = 10.704, p = 0.007, ηp2 = 0.493) and two (F(1,12) = 7.746, p = .018, ηp2 = .413).

CONCLUSION

The training intervention improved endurance performance in both groups, with no further benefit observed from the MC-adapted polarized training in a group-based analysis. Replications with an extended intervention period, a larger sample size, and a more reliable MC determination are warranted.

The Menstrual Health Manager (MHM): A Resource to Reduce Discrepancies Between Science and Practice in Sport and Exercise

Inadequate research on female health and performance; the complexity of the research; low menstrual health literacy of athletes, coaches, and support staff; and ethical and cultural sensitivities are all recognized as barriers to effective health monitoring for females in sports. Frameworks have been developed for academics to follow to help improve the quality of female-specific research. However, a similar resource that enables correct terminology, and use of health monitoring techniques has not been provided for sporting organizations, coaches, support staff or athletes. Therefore, this critical commentary presents a new resource, the Menstrual Health Manager. This resource may be used to determine the level of menstrual health monitoring detail that may be used by organisations, coaches or athletes, and specifies what reproductive health details the data will provide. This resource aims to provide organizations and coaches with a means of understanding the data that inform their decisions for female athletes. Utilization of this resource may aid in the consistent use of terminology and methods for female-specific health monitoring in both sports and research.

Monitoring of sprint and change of direction velocity, vertical jump height, and repeated sprint ability in sub-elite female football players throughout their menstrual cycle

AIMS

The aim of this study was to investigate the associations between the early follicular (EF, i.e., menstruation), late follicular (LF), and middle luteal (ML) phases of the menstrual cycle and different factors that may influence football performance.

METHODS

To this end, 11 eumenorrheic sub-elite female football players underwent field tests to assess sprint speed, lower extremity power, repeated sprint ability, velocity on change of direction, and technical skills at each cycle phase.

RESULTS

Performance during the 15-m change of direction ability test, 15-m ball dribbling test, squat jump height, total sprint time [sum of 7 sprints] and decrement score [(mean sprint time/best sprint time × 100) - 100], maximum and mean heart rate, and perceived exertion did not significantly differ among menstrual cycle phases. Conversely, the linear sprint velocity over 10, 20, 30-m distances was decreased in EF vs LF (10-, 20- and 30-m) and in ML vs LF (10- and 20-m) (p < 0.05). The 40-m sprint velocity did not change in the different menstrual cycle phases.

CONCLUSION

Overall, our study suggests that sex hormone fluctuations during the menstrual cycle are not associated with vertical jump, velocity on change of direction, and repeated sprint ability, but may influence linear sprint velocity over short distances (10, 20, and 30 m).

Menstrual cycle phase differences in myofiber damage and macrophage infiltration following electrical stimulation-induced muscle injury

The purpose of this study was to examine the effects of menstrual cycle phase on myofiber injury, regenerative events, and inflammation after electrical stimulation (ES)-induced myofiber damage. Twenty-eight premenopausal women (20.8 ± 2 yr) were randomized into early follicular (EF; n = 14) and late follicular (LF; n = 14) groups. After menstrual cycle tracking and phase confirmation, subjects underwent 200 electrically stimulated eccentric muscle contractions 1 wk after providing a muscle biopsy. Seven days post-ES, subjects provided a final biopsy. Primary outcomes included serum estradiol, indirect markers of muscle damage, direct indicators of myofiber necrosis and regeneration, satellite cell number, and macrophage infiltration. Women in the LF group had higher serum estradiol (122.1 ± 23.4 vs. 81.7 ± 30.8 pg/mL; P < 0.001) than in the EF group on the day of ES. Although the EF group recovered baseline maximal isometric strength by 4 days post-ES, the LF group did not. Only women in the LF group showed significant and consistent evidence of myofiber necrosis and regeneration pre- to post-ES. Despite showing more evidence of myofiber damage, women in the LF group also experienced reduced total and CD206+ macrophage infiltration relative to the EF group. Satellite cell quantity increased significantly post-ES in both groups, with no differences between groups. Collectively, the data suggest that the high-estrogen LF phase may be associated with increased susceptibility to myofiber injury while also limiting the subsequent intramuscular inflammatory response.NEW & NOTEWORTHY The menstrual cycle has widespread physiological effects across many systems, including skeletal muscle. In this study, we show that women in the late follicular phase of the menstrual cycle may be more susceptible to myofiber necrosis following electrical stimulation. We also show reduced evidence of inflammation in the late follicular phase. This is the first study to demonstrate a difference in the response of human skeletal muscle to a necrotic stimulus across a menstrual cycle.

Influence of menstrual cycle and oral contraceptive phases on strength performance, neuromuscular fatigue, and perceived exertion

The primary aim of the study was to assess differences in strength performance, neuromuscular fatigue, and perceived exertion across phases of the menstrual cycle [MC; early follicular (eFP), late follicular (lFP), and mid-luteal phase (mLP)] and oral contraceptives [OCs; active pill phase (aPP) and nonactive pill phase (nPP)]. The secondary aim was to analyze the influence of fluctuating serum 17β-estradiol and progesterone concentrations on these parameters in naturally menstruating women. Thirty-four women (21 with a natural MC and 13 using OCs) completed three or two experimental sessions, respectively. Mean propulsive velocity (MPVmean) and total number of repetitions (REPtotal) were assessed during a power [3 × 8 at 60% 1RM (one-repetition maximum)] and hypertrophy squat loading (3 sets to failure at 70% 1RM), respectively. Changes in bench press and squat MPV at 60% 1RM in response to the loadings were used as surrogates for nonlocal and local fatigue, respectively. Total blood lactate accumulation (BLAA) and markers of perceived exertion were assessed in each session. No significant differences between any of the MC or OC phases were observed for MPVmean, REPtotal, nonlocal and local fatigue, and markers of perceived exertion (all P > 0.050). A higher intraindividual 17β-estradiol concentration was significantly associated with a lower MPVmean (P = 0.019). BLAA was significantly higher in the lFP than in the mLP (P = 0.019) and negatively associated with the intraindividual progesterone concentration (P = 0.005). Although 17β-estradiol may negatively influence the MPV, it appears that fluctuations of both sex hormones across the MC and OC phases are not prominent enough to induce significant or practically relevant changes in the assessed parameters.NEW & NOTEWORTHY Although a high intraindividual 17β-estradiol concentration was associated with a lower movement velocity, markers of strength performance and surrogates for nonlocal and local fatigue remained unaffected by MC and OC phases. Blood lactate accumulation was significantly reduced in the mLP. Furthermore, our findings suggest that the impact of the MC phases varies greatly among individuals. Individuals with high fluctuations in sex hormone concentrations may experience relevant changes in the assessed parameters.

Analysis of combinatory effects of free weight resistance training and a high-protein diet on body composition and strength capacity in postmenopausal women - A 12-week randomized controlled trial

BACKGROUND

Menopause has a significant impact on the endocrine system of middle-aged women, resulting in a loss of skeletal muscle mass (SMM), changes in fat mass (FM) and a reduction in strength capacity. Resistance training (RT) and a high-protein diet (HPD) are effective methods for maintaining or increasing SMM. This study aims to determine the effects of HPD and RT on body composition, muscle thickness and strength capacity in postmenopausal women.

METHODS

In total 55 healthy postmenopausal women (age: 58.2 ± 5.6 years, weight 69.1 ± 9.6 kg, height 166.5 ± 6.5 cm) successfully participated in the study. The women were randomly assigned to either group: training + protein (2.5 g/kg fat-free mass (FFM)) (n = 15; TP); only training (n = 12; T); only protein (2.5 g/kg FFM) (n = 14; CP) or control (n = 14; C). TP and T performed RT for 12 weeks with three training sessions and five exercises each. CP and C were prohibited from training during the period. The main parameters analysed for body composition were FFM, SMM, FM, muscle thickness of the M. rectus femoris, M. biceps femoris, M. triceps brachii and M. biceps brachii muscles. Strength was tested using a dynamometer for grip strength and 1-RM in the squat (BBS) and deadlift (DL).

RESULTS

The SMM significantly increased by RT (TP: (Δ+1.4 ± 0.9 kg; p < 0.05; d = 0.4; T: Δ+1.2 ± 1.3kg; p < 0.05; d = 0.3) and FM could be reduced only in T: (Δ-2.4 ± 2.9 kg; p < 0.05; d = 0.3). In muscle thickness a significant increase in the M. biceps brachii in both training groups (TP: (Δ+0.4 ± 0.3 cm; p < 0.05; d = 1.6; T: (Δ+0.3 ± 0.3 cm; p < 0.05; d = 0.9) and in M. biceps femoris only in TP (Δ+0.3 ± 0.4 cm; p < 0.05; d = 0.9) were observed. HPD without training does not affect body composition, A significant increase in grip strength (TP: Δ+4.7 ± 2.4 kg; (p < 0.05; d = 1.5; T: (Δ+3.6 ± 3.0 kg; p < 0.05; d = 0.8), in BBS (TP: (Δ+30.0 ± 14.2 kg; p < 0.05; d = 1.5; T: (Δ+34.0 ± 12.0 kg; p < 0.05; d = 2.4) and in DL (TP: (Δ+20.8 ± 10.3 kg; p < 0.05; d = 1.6; T: (Δ+22.1 ± 7.6 kg; p < 0.05; d = 2.0) was observed in both training groups. The CP also recorded a significant increase in the BBS (Δ+7.5 ± 5.4 kg; p < 0.05; d = 0.4) and in DL (Δ+5.5 ± 7.7 kg; p < 0.05; d = 0.5). No significant differences were detected for TP and T for any of the parameters.

CONCLUSION

The results indicate that RT enhances body composition and strength capacity in postmenopausal women and is a preventive strategy against muscle atrophy. Besides HPD without training has a trivial significant effect on BBS and DL. HPD with RT has no clear additive effect on body composition and strength capacity. Further studies are needed to confirm these observations.

Role of Cardiorespiratory Fitness, Aerobic, Exercise and Sports Participation in Female Cognition: A Scoping Review : Sports, Fitness, and Cognition

BACKGROUND

The impact of cardiorespiratory fitness (CRF) on cognition is thought to be mediated by brain-derived neurotrophic factor. Aerobic exercise can increase CRF through various activities, including sports participation. The relationship between these factors in females has yet to be elucidated.

OBJECTIVE

This review aims to map the current literature on the effects of aerobic exercise, sports participation, and CRF in healthy adult females, with sub-topics of pregnancy and menstrual cycle periodicity.

METHODS

A scoping review of the literature was conducted following PRISMA guidelines and the PCC mnemonic (population, concept, and context). The following five databases were screened: CINAHL, Medline, Web of Science, SPORTDiscus, and Scopus. Eligible articles included healthy adult females, investigated aerobic exercise, sports participation or CRF, and linked outcomes to cognition. Data from included manuscripts was extracted and analyzed. Two sub-population groupings (pregnant individuals and menstrual cycle) were established to further aid the interpretation of the findings.

RESULTS

Of the 300 titles and abstracts screened, 74 were eligible for full-text screening, and 28 were included in the scoping review. Of the 28 included, 14 did not control for or report on menstrual cycle phase or sex hormones.

CONCLUSION

This scoping review found an inverse 'U' relationship between aerobic exercise and cognition, demonstrating an optimal dose of aerobic exercise to benefit cognitive functions. As estrogen may impact the relationship between CRF and neural growth factors, more research is needed on this pathway, independent of the menstrual cycle, to determine potential beneficial effects. It is currently unknown whether sports participation can independently impact cognition.

Effects of In-Season Strength Training on Physical Fitness and Injury Prevention in North African Elite Young Female Soccer Players

BACKGROUND

Strength training (ST) primarily enhances physical fitness (e.g., muscle strength, power, speed) and bone density in female soccer players. Less information is available on the injury preventive effects of ST in female athletes. Accordingly, this study aimed to investigate the effects of a 12-week in-season ST on measures of physical fitness and injury occurrence in young elite female soccer players.

METHODS

Thirty elite female soccer players (15.4 ± 1.9 years; maturity offset + 2.3 ± 1.1 years) participated in this study, and were randomly assigned to a strength training group (STG, n = 14) or an active control (CG, n = 16) group. ST lasted twelve weeks and included full body muscle strengthening exercises using primarily weight machines at progressive intensities ranging between 40 and 85% of the one-repetition-maximum (1-RM). The CG practiced a traditional soccer training program. Overall, training volumes of the two groups were similar with a training load (rating of perceived exertion × time) of 1158.4 ± 67.7 arbitrary unity (AU) for the STG and 1188.8 ± 44.1 AU for the CG. Pre and post training, the following physical fitness tests were applied: dynamic muscle strength (relative [to body mass] and absolute 1-RM bench/leg press, lat-pull down), jump performance (countermovement jump [CMJ], squat jump [SJ], five-jump-test [5JT]), linear-sprint speed (5-m, 10-m, 30-m), change-of-direction speed (T-test with and without ball), sport-specific performance (Yo-Yo Intermittent Level1 [YYIRTL1], and repeated shuttle sprint ability [RSSA]). The injury rate per 1000-h exposure was monitored throughout the soccer season.

RESULTS

No significant baseline differences were observed between groups. Statistically significant group-by-time interactions were found for absolute (p < 0.001, d = 2.59) and relative 1-RM bench press (p < 0.001, d = 2.39), absolute 1-RM lat-pull down (p < 0.001, d = 1.68), and relative 1-RM leg press (p < 0.001, d = 1.72). Significant group-by-time interactions were observed for CMJ (p = 0.005, d = 1.27), RSSAmean (p = 0.007, d = 0.81), and RSSAtotal (p < 0.001, d = 1.90). Post-hoc tests indicated that the STG group demonstrated greater improvements in all tested variables compared to CG (1.2 < d < 2.5). However, no significant interaction effects were noted for measures of linear sprint speed and YYIRTL1 performance. Additionally, non-contact injuries during the season were significantly lower (p = 0.003, d = 1.31) in the STG (0.48/1000 h of exposure) than the CG (2.62/1000 h of exposure).

CONCLUSIONS

Twelve weeks of an in-season ST resulted in larger physical fitness improvements and fewer injuries compared with an active control in elite young female soccer players. Accordingly, ST should be systematically applied in female soccer to enhance performance and prevent injuries.

Does the Menstrual Cycle Influence Aerobic Capacity in Endurance-Trained Women?

Purpose: The aim was to study if aerobic capacity varies during different phases of the menstrual cycle (MC) in endurance-trained female athletes. Methods: Ten endurance-trained eumenorrheic women performed a submaximal test followed by an incremental test until exhaustion three times during one MC, early follicular phase (EFP), late follicular phase (LFP), and midluteal phase (MLP). During the submaximal test, the respiratory exchange ratio (RER) and utilization of fat and carbohydrates were analyzed; and, during the incremental test, VO2 peak, maximal heart rate, utilization of fat and carbohydrates, and RER were analyzed. Lactate levels were analyzed at rest, during the submaximal test, and after the incremental test. The anaerobic threshold was determined at RER = 1. Results: No significant differences (p < .05) between the MC phases were seen in a maximal heart rate or VO2peak. Similarly, VO2, heart rate, RER, fatty acid oxidation, and carbohydrate oxidation at 70, 80, 90, and 100% of VO2peak did not differ significantly between MC phases. There were no significant differences between these phases in resting lactate before the test or during the submaximal tests, though there was a significant difference in lactate concentration 3 minutes after the incremental test between the EFP and the LFP (p = .043). Conclusion: This study did not display variations in physiological parameters between EFP, LFP, and MLP, indicating similar aerobic capacity despite hormonal variations. This knowledge may be useful when planning for competition in aerobic events.

Agreement Between the 2- and 3-Step Methods for Identifying Subtle Menstrual Disturbances

Recent methodological recommendations suggest the use of the "3-step method," consisting of calendar-based counting, urinary ovulation testing, and serum blood sampling, for the identification of subtle menstrual disturbances (SMDs). However, the use of the 3-step method is not always feasible, so a less demanding combination of calendar-based counting and urinary ovulation testing, that is, the 2-step method, may be a viable alternative.

PURPOSE

To investigate the agreement between the 2- and 3-step methods for the detection of SMDs.

METHODS

Menstrual cycles (MCs, 98) of 59 athletes were assessed using the 2- and 3-step methods. Regular-length MCs (ie, ≥21 and ≤35 d) were classified as either having no SMD (luteal phase length ≥10 d, midluteal progesterone concentration ≥16 nmol·L-1, and being ovulatory) or having an SMD (eg, short luteal phase [<10 d], inadequate luteal phase [midluteal progesterone concentration <16 nmol·L-1], or being anovulatory). Method agreement was assessed using the McNemar test and Cohen kappa (κ).

RESULTS

Substantial agreement was observed between methods (κ = .72; 95% CI, .53-.91), but the 2-step method did not detect all MCs with an SMD, resulting in evidence of systematic bias (χ2 = 5.14; P = .023). The 2-step method detected 61.1% of MCs that had an SMD ([51.4, 70.8]), as verified using the 3-step method, and correctly identified 100% of MCs without an SMD.

CONCLUSIONS

MCs classified as being disturbed using the 2-step method could be considered valid evidence of SMDs. However, MCs classified without SMDs do not definitively confirm their absence, due to the proven underdetection via the 2-step method.

At What Point in the Menstrual Cycle Are the Pelvic Floor Muscles at Their Weakest?

Pelvic floor muscle (PFM) strength is a critical factor for optimal pelvic floor function. Fluctuations in strength values based on different phases of the menstrual cycle (MC) could signify a need for a paradigm shift in evaluating, approaching, and planning training. This research aims to examine and contrast the pelvic floor muscle strength during different phases of the menstrual cycle. A prospective observational study employing digital assessment with the modified Oxford scale and vaginal dynamometry measurements was performed, in order to assess the baseline strength and the contraction strength of the PFMs in eumenorrheic females at three different phases of the MC: the early follicular phase (EFP), the late follicular phase (LFP), and the mid-luteal phase (MLP). During two complete cycles, tympanic temperature and body weight were measured and the urinary luteinizing hormone concentration was tested to determine the time of ovulation. In total, 216 dynamometric measurements of PFM strength were obtained from eighteen nulliparous women (25.72 ± 5.03 years). There were no differences between the baseline strength (p = 0.886) and the contraction strength (p = 0.756) with the dynamometric speculum. In the post hoc analysis, the baseline strength, contraction strength, and strength showed no significant differences between MC phases. As no differences in PFM strength in women were found, the PFMs do not seem to be weaker at any time during the menstrual cycle. It appears that the assessment, establishment, and monitoring of a PFM training program could be initiated at any point in the cycle.

Testing in Intermittent Sports-Importance for Training and Performance Optimization in Adult Athletes

ABSTRACT

Performance in intermittent sports relies on the interplay between multiple physiological systems determining the capacity to perform short explosive efforts as well as repeated intense actions with limited recovery over the course of an entire game. Testing should reflect these demands to allow for sport- and position-specific capacity analyses that eventually may translate into optimized training and improved performance. This may include individual load management and optimized training prescription, intensity targeting for specific positions or individual athletes, as well as benchmarking for monitoring of training progression and enhanced engagement of athletes. This review provides an overview of available tests in different exercise domains identified as relevant (from assessment of single explosive actions to intermittent endurance capacity), forming the basis for recommendations on how to compose a comprehensive yet feasible test battery that may be integrated into the seasonal competition and training plan. The test procedures should cover the performance spectrum of relevance for the individual athlete-also in team sports to account for positional differences. We emphasize the benefits of sport-specific tests, highlight parameters of importance for test standardization, and discuss how the applied test battery may be supplemented with secondary tests directed toward specific energy systems to allow for more in-depth analyses when required (e.g., in terms of an underperforming athlete). The synergy between testing and tracking of match performance (utilizing time-motion or global positioning systems) is highlighted, and although tracking cannot substitute for testing, combining the tools may provide a comprehensive overview of the physiological demands and performance during competition contextualized to the athletes' maximal exercise capacity.

Myths and Methodologies: Standardisation in human physiology research-should we control the controllables?

The premise of research in human physiology is to explore a multifaceted system whilst identifying one or a few outcomes of interest. Therefore, the control of potentially confounding variables requires careful thought regarding the extent of control and complexity of standardisation. One common factor to control prior to testing is diet, as food and fluid provision may deviate from participants' habitual diets, yet a self-report and replication method can be flawed by under-reporting. Researchers may also need to consider standardisation of physical activity, whether it be through familiarisation trials, wash-out periods, or guidance on levels of physical activity to be achieved before trials. In terms of pharmacological agents, the ethical implications of standardisation require researchers to carefully consider how medications, caffeine consumption and oral contraceptive prescriptions may affect the study. For research in females, it should be considered whether standardisation between- or within-participants in regards to menstrual cycle phase is most relevant. The timing of measurements relative to various other daily events is relevant to all physiological research and so it can be important to standardise when measurements are made. This review summarises the areas of standardisation which we hope will be considered useful to anyone involved in human physiology research, including when and how one can apply standardisation to various contexts.

Menstrual cycle patterns and their relationship with measures of well-being and perceived performance metrics in competitive and recreational resistance-trained athletes

BACKGROUND

There is mixed evidence on how the menstrual cycle (MC) affects sports performance, with many studies showing variations in performance during different phases of the MC, while other evidence shows that the MC's effects on performance may be trivial. Therefore, this exploratory longitudinal monitoring study was designed to investigate MC characteristics and symptoms in a resistance-trained (RT) population to look for associations between measures of well-being and perceived performance metrics across the MC.

METHODS

RT females reported their workout habits, perceived performance metrics, and measures of well-being while tracking their MC with detailed methods via daily check-ins in an app.

RESULTS

Most MC characteristics and symptoms in the present RT population aligned with previous research on the general population. However, the frequency of irregular cycles was higher than in previous research on the general population. The amount of individual variation and within-subject cycle-to-cycle variation in MC characteristics and MC symptoms was also high. All measures of well-being were significantly associated with specific days of the MC, demonstrating a change in well-being based on the timing of the MC. Several perceived performance metrics were significantly associated with changes across the MC, while others were not.

CONCLUSIONS

Overall, with the current evidence as it stands, a highly individualized approach should be taken for any training or performance considerations surrounding the MC due to the high levels of individual variation.

Exploring the effect of the menstrual cycle or oral contraception on elite athletes' training responses when workload is not objectively quantifiable: the MILS approach and findings from female Olympians

Objectives

Develop the Markov Index Load State (MILS) model, based on hidden Markov chains, to assess athletes' workload responses and investigate the effects of menstrual cycle (MC)/oral contraception (OC), sex steroids hormones and wellness on elite athletes' training.

Methods

On a 7-month longitudinal follow-up, daily training (volume and perceived effort, n=2200) and wellness (reported sleep quality and quantity, fitness, mood, menstrual symptoms, n=2509) data were collected from 24 female rowers and skiers preparing for the Olympics. 51 MC and 54 OC full cycles relying on 214 salivary hormone samples were analysed. MC/OC cycles were normalised, converted in % from 0% (first bleeding/pill withdrawal day) to 100% (end).

Results

MILS identified three chronic workload response states: 'easy', 'moderate' and 'hard'. A cyclic training response linked to MC or OC (95% CI) was observed, primarily related to progesterone level (p=8.23e-03 and 5.72e-03 for the easy and hard state, respectively). MC athletes predominantly exhibited the 'easy' state during the cycle's first half (8%-53%), transitioning to the 'hard' state post-estimated ovulation (63%-96%). OC users had an increased 'hard' state (4%-32%) during pill withdrawal, transitioning to 'easy' (50%-60%) when on the pill. Wellness metrics influenced the training load response: better sleep quality (p=5.20e-04), mood (p=8.94e-06) and fitness (p=6.29e-03) increased the likelihood of the 'easy' state. Menstrual symptoms increased the 'hard' state probability (p=5.92e-02).

Conclusion

The MILS model, leveraging hidden Markov chains, effectively analyses cumulative training load responses. The model identified cyclic training responses linked to MC/OC in elite female athletes.

Influence of the Menstrual Cycle and Training on the Performance of a Perturbed Single-Leg Squatting Task in Female Collegiate Athletes

Background

Anterior cruciate ligament (ACL) injuries often occur when an athlete experiences an unexpected disruption, or perturbation, during sports. ACL injury rates may also be influenced by the menstrual cycle.

Purpose

To determine whether training adaptations to knee control and muscle activity during a perturbed single-leg squatting (SLS) task depend on menstrual cycle phase in female athletes.

Study Design

Controlled laboratory study.

Methods

A total of 21 healthy female collegiate athletes (current or former [<3 years]) who competed in 9 different sports performed an SLS task in which they attempted to match their knee position (user signal) to a target signal. The protocol consisted of a 9-condition pretest, 5 sets of 3 training trials, and a 9-condition posttest. One perturbation was delivered in each condition by altering the resistance of the device. Sagittal knee control (absolute error between the target signal and user signal) was assessed using a potentiometer. Muscle activity during perturbed squat cycles was normalized to maximal activation and to corresponding muscle activity during unperturbed squat cycles (%unperturbed) within the same test condition. Athletes performed the protocol during a distinct menstrual cycle phase (early follicular [EF], late follicular [LF], midluteal [ML]). Two-way mixed analysis of variance was used to determine the effects of the menstrual cycle and training on knee control and muscle activity during task performance. Venous blood was collected for hormonal analysis, and a series of health questionnaires and anthropometric measures were also assessed to determine differences among the menstrual cycle groups.

Results

After training, athletes demonstrated better knee control during the perturbed squat cycles (lower absolute error, P < .001) and greater soleus feedback responses to the perturbation (%unperturbed, P = .035). Better knee control was demonstrated in the ML phase versus the EF phase during unperturbed and perturbed squat cycles (P < .039 for both). Quadriceps activation was greater in the ML phase compared with the EF and LF phases, both immediately before and after the perturbation (P < .001 for all).

Conclusion

Athletes learned to improve knee control during the perturbed performance regardless of menstrual cycle phase. The best knee control and greatest quadriceps activation during the perturbed squatting task was found in the ML phase.

Clinical Relevance

These findings may correspond to a lower incidence of ACL injury in the luteal phase and alterations in exercise performance across the menstrual cycle.

The prevalence of menstrual cycle symptoms and their association with mental health and sleep in German exercising women and athletes

OBJECTIVES

Menstrual cycle symptoms are very common in female athletes. However, more evidence about the association between menstrual cycle characteristics and symptoms with sleep and mental health in athletes needs to be gathered. This study aimed to examine this association in German exercising women and athletes.

DESIGN

322 women (mean age: 23.13 ± 4.36) participated in a cross-sectional study. The survey included the Menstrual Symptom index (MSi), the Depression Anxiety Stress Scales (DASS-21), the Pittsburgh Sleep Quality Index (PSQI), and the Athletes Sleep Behavior Questionnaire (ASBQ). Additionally, demographic, sport-specific data and further menstrual cycle characteristics were examined. Multiple regression models were used for the statistical analyses.

RESULTS

The MSi score demonstrated a highly significant (p < 0.001) positive association with Depression, Anxiety, Stress, PSQI, and ASBQ. The most prevalent menstrual cycle symptoms were cravings/increased appetite, mood changes/anxiety, and tiredness/fatigue. A difference between individual and team sport athletes could not be found. Moreover, there was no association between the constructs and menses length, irregularity, or heaviness of bleeding.

CONCLUSIONS

Menstrual cycle symptoms occur very frequently in female athletes. In this study, they were related to mental health, sleep quality, and sleep behavior, regardless of the cycle phase. This evidence demonstrates the relevance of considering the menstrual cycle and menstrual symptoms in future studies with female athletes and in sport practice.

Are there sex differences in the variability of fasting metabolism?

There is evidence across species and across many traits that males display greater between-individual variance. In contrast, (premenopausal) females display large within-individual variance in sex hormone concentrations, which can increase within-individual variance in many other parameters. The latter may contribute to the lower representation of females in metabolic research. This study is a pooled secondary analysis of data from seven crossover studies to investigate the between-individual and the within-individual variance in fasting plasma metabolites, resting metabolic rate (RMR), and body mass. Females demonstrated higher within-individual variability of plasma 17β-estradiol [coefficient of variation (CV): 15 ± 15% for males vs. 38 ± 34% for females, P < 0.001] and progesterone concentrations (CV: 13 ± 11% for males vs. 52 ± 51% for females, P < 0.001) but there were no meaningful differences in the variability of plasma glucose (CV: 4 ± 3% for males vs. 5 ± 5% for females), insulin, lactate, triglycerides (CV: 15 ± 9% for males vs. 15 ± 10% for females), and esterified fatty acid concentrations or in RMR and body mass (CV: 0.43 ± 0.34% for males vs. for 0.42 ± 0.33% females; P > 0.05 for all outcomes). Males displayed higher between-individual variance in RMR compared with females (SD: 224 kcal·day-1 for males vs. 151 kcal·day-1 for females). In conclusion, these data do not provide evidence that females show greater within-individual variability in many fasting metabolic variables, RMR, or body mass compared with males. We conclude that including females in metabolic research is unlikely to introduce greater within-individual variance when using the recruitment and control procedures described in these studies.NEW & NOTEWORTHY To investigate the within-individual variability in metabolic parameters in males and females, we performed a pooled secondary analysis of fasting blood samples, resting metabolic rate, and body mass from seven crossover studies. We found a greater day-to-day variation in 17β-estradiol and progesterone in females compared with males but no meaningful difference in within-individual variability of fasting plasma glucose, insulin, lactate, triglycerides, NEFA, resting metabolic rate, or body mass between females and males.

The Variability of the Components of Fitness along the Menstrual Cycle

This study aims to determine the variability of the components of fitness along the menstrual cycle (MC) of physically active eumenorrheic women. Fifteen subjects were monitored along two consecutive MCs through the calendar-based counting method in combination with a urine luteinizing hormone surge kit. Subjects were tested at the early follicular phase (EFP), pre-ovulatory or late follicular phase (LFP), and post-ovulatory or mid-luteal phase (MLP). In each session, the back squat one-repetition maximum (1-RM), maximum fat oxidation (MFO), maximum oxygen uptake (VO2max) and acute recovery capacity were determined. The results revealed a wide variability among components of fitness and a low to high variability among subjects (acute recovery: 3.6% [range 1.5 to 9.5%]; back squat 1-RM: 6.1% [range 2.2 to 11%]; VO2max: 6.6% [range 1.1 to 15%]; MFO: 23% [range 4.6 to 35%]). Despite the individual nature, considering the number and magnitude of the responses in each MC phase, VO2max and acute recovery capacity tended to be enhanced at the LFP, the MFO at the MLP, and the back squat 1-RM remained stable along the MC. Thus, practitioners are aware of which components are susceptible to change along the MC phase, but an individual monitoring is recommended.

Effect of a graded running race on lower limb muscle damage, jump performance and muscle soreness in men and women

PURPOSE

Delayed structural and functional recovery after a 20 km graded running race was analyzed with respect to the sex effect.

METHODS

Thirteen female and 14 male recreational runners completed the race and three test sessions: one before (PRE) and two after, once on Day 1 or 2 (D1-2) and then on Day 3 or 4 (D3-4). Muscle damage was assessed indirectly using ultrasonography to quantify changes in cross-sectional area (CSA) of 10 lower-limb muscles. Delayed onset of muscle soreness (DOMS) was assessed for three muscle groups. Functional recovery was quantified by kinetic analysis of a squat jump (SJ) and a drop jump (DJ) test performed on a sledge ergometer. Linear mixed models were used to assess control group reproducibility and recovery patterns according to sex.

RESULTS

Regardless of sex, DOMS peaked at D1-2 for all muscle groups and resolved at D3-4. CSA was increased in each muscle group until D3-4, especially in the semimembranosus muscle. A specific increase was found in the short head of the biceps femoris in women. Regardless of sex, SJ and DJ performances declined up to D3-4. Depending on the muscle, positive and/or negative correlations were found between structural and functional changes. Some of these were sex-specific.

CONCLUSION

Structural and functional recovery was incomplete in both sexes up to D3-4, although DOMS had disappeared. More emphasis should be placed on hamstring muscle recovery. Highlighting the intermuscular compensations that can occur during multi-joint testing tasks, the structural-functional relationships were either positive or negative, muscle- and sex-dependent.

Effects of the menstrual cycle on the performance of female football players. A systematic review

Background

Women's football has been booming for a few years now, which has led to an increase in the expectation of the players' performance, leading to a more detailed study of women's physiology in the field of sports.

Objectives

To analyze the scientific evidence on the influence of menstruation on the performance of female footballers, as well as to analyze the methodological quality of the studies included in this review.

Materials and methods

The possible hormonal effects of the menstrual cycle phases on the performance of female footballers were analyzed. The databases used to conduct the searches were Pubmed, Scopus, Virtual Health Library, Web of Science, EBSCO and the Cochrane Library. All included studies met the inclusion criteria. The Cochrane risk of bias tool was used. This systematic review protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023390652).

Results

A total of nine clinical trials were included in this review. A low quality of evidence was observed in the studies. Not all the results support the idea that the menstrual cycle phases can alter the performance of female footballers.

Conclusion

This systematic review shows that there is a great deal of controversy about the influence of the menstrual cycle phases on the performance of female footballers. Studies are focused on solely biological factors and gender is normally no part of those studies. Further research with larger samples, and taking not only biological but also sociological factors, are necessary to determine the effects of menstruation on the performance of female footballers.

Changes in the mechanical properties of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases

Background

This study aimed to determine changes in the muscle and tendon stiffness of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases, and check for possible relations between muscle and tendon stiffness in each phase.

Methods

The sample consisted of 15 female university students with regular menstrual cycles. The basal body temperature method, ovulation kit, and salivary estradiol concentration measurement were used to estimate the early follicular and early luteal phases. A portable digital palpation device measured muscle-tendon stiffness in the early follicular and early luteal phases. The measurement sites were the rectus femoris (RF), vastus medialis (VM), patellar tendon (PT), medial head of gastrocnemius muscle, soleus muscle, and Achilles tendon.

Results

No statistically significant differences in the thigh and lower leg muscle-tendon unit stiffness were seen between the early follicular and early luteal phases. Significant positive correlations were found between the stiffness of the RF and PT (r = 0.608, p = 0.016) and between the VM and PT (r = 0.737, p = 0.002) during the early luteal phase.

Conclusion

The present results suggest that the stiffness of leg muscle-tendon units of the anterior thigh and posterior lower leg do not change between the early follicular and early luteal phases and that tendons may be stiffer in those women who have stiffer anterior thigh muscles during the early luteal phase.

Influence of menstrual cycle phase and oral contraceptive phase on exercise performance in endurance-trained females

BACKGROUND

Limited data exists on the influence of menstrual cycle (MC) phase and oral contraceptive (OC) phase on physical performance in endurance-trained females due to poor control regarding MC verification and differentiation. We aimed to evaluate exercise performance and the respiratory response to exercise in three distinct phases of the MC and OC cycle in endurance-trained females.

METHODS

Using a prospective cohort study design, we recruited trained females (Vo2max 52±4 mL O2/min/kg) who were either not using oral contraceptives (NOC) or using monophasic OCs. NOC were tested in the early and late follicular phase (FP) and the mid-luteal phase (LP). OC-users were tested in the withdrawal phase (WP) and two times in the active OC phase (OCP). The test battery included DXA scans, blood sampling, a submaximal bike test, a maximal isometric knee-extensor strength test, 4 and 20-second bike sprints, and a 6 min time trial on a bike. MC phases were verified by the use of ovulation kits and circulating sex hormone levels.

RESULTS

After the exclusion of four NOCs due to inadequate sex hormone levels, 11 NOC and 13 OC users were included in the final analysis. 6 min time trial performance, sprint performance, and most submaximal exercise intensity variables did not differ between MC phases and OC cycle phases. However, in NOC, ventilation (L/min) during exercise at 30% of aerobic peak power was 7.6% lower in the late FP compared to the LP (P<0.05). In OC users, muscle strength was 3.9% higher in the early OCP compared to WP (P<0.05), whereas body mass was higher in the late OCP compared to WP (P<0.05).

CONCLUSIONS

Collectively, our study suggests that MC phase and OCP influence exercise performance to a limited extent in endurance-trained females.

Perspectives on Concurrent Strength and Endurance Training in Healthy Adult Females: A Systematic Review

BACKGROUND

Both strength and endurance training are included in global exercise recommendations and are the main components of training programs for competitive sports. While an abundance of research has been published regarding concurrent strength and endurance training, only a small portion of this research has been conducted in females or has addressed their unique physiological circumstances (e.g., hormonal profiles related to menstrual cycle phase, menstrual dysfunction, and hormonal contraceptive use), which may influence training responses and adaptations.

OBJECTIVE

The aim was to complete a systematic review of the scientific literature regarding training adaptations following concurrent strength and endurance training in apparently healthy adult females.

METHODS

A systematic electronic search for articles was performed in July 2021 and again in December 2022 using PubMed and Medline. This review followed, where applicable, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was assessed using a modified Downs and Black checklist. Inclusion criteria were (1) fully published peer-reviewed publications; (2) study published in English; (3) participants were healthy normal weight or overweight females of reproductive age (mean age between > 18 and < 50) or presented as a group (n > 5) in studies including both females and males and where female results were reported separately; (4) participants were randomly assigned to intervention groups, when warranted, and the study included measures of maximal strength and endurance performance; and (5) the duration of the intervention was ≥ 8 weeks to ensure a meaningful training duration.

RESULTS

Fourteen studies met the inclusion criteria (seven combined strength training with running, four with cycling, and three with rowing or cross-country skiing). These studies indicated that concurrent strength and endurance training generally increases parameters associated with strength and endurance performance in female participants, while several other health benefits such as, e.g., improved body composition and blood lipid profile were reported in individual studies. The presence of an "interference effect" in females could not be assessed from the included studies as this was not the focus of any included research and single-mode training groups were not always included alongside concurrent training groups. Importantly, the influence of concurrent training on fast-force production was limited, while the unique circumstances affecting females were not considered/reported in most studies. Overall study quality was low to moderate.

CONCLUSION

Concurrent strength and endurance training appears to be beneficial in increasing strength and endurance capacity in females; however, multiple research paradigms must be explored to better understand the influence of concurrent training modalities in females. Future research should explore the influence of concurrent strength and endurance training on fast-force production, the possible presence of an "interference effect" in athletic populations, and the influence of unique circumstances, such as hormone profile, on training responses and adaptations.

Impact of menstrual cycle or combined oral contraception on elite female cyclists' training responses through a clustering analysis of training sessions

Objectives

(i) To classify training sessions of elite female cyclists according to an intensity index based on a longitudinal follow-up using multiparametric data collected in situ (ii) to measure the effect of estimated menstrual cycle (MC) phases and oral contraceptive pills (OC) phases on the athletes' training responses on each type of training identified.

Method

Thirteen elite French cyclists were followed up over 30 months and 5,190 training sessions were collected and 81 MC/OCs full cycles analyzed. Power sensors and position devices captured training data in situ, which was summarized into 14 external load variables. Principal Component Analysis and K-means clustering were used to identify cycling sessions according to an intensity load index. The clusters were then verified and categorized through the analysis of heart rate and rate of perceived effort. A calendar method was used to estimate 3 phases of the MC: menstruation, mid-cycle phase (MP) and late-cycle phase (LP). Two phases were defined among monophasic OC users: pills' taking/withdrawal.

Results

Four main types of training effort were identified: Intensive, Long, Medium and Light. In the MC group (n = 7; 52 cycles), the intensity index is 8% higher during the mid-cycle (vs. menstrual phase, p = 0.032) in the Intensive effort sessions. No differences were observed in Long, Medium or Light effort, nor between the phases of pills' taking/withdrawal among OC users.

Conclusion

The clustering analyses developed allows a training classification and a robust method to investigate the influence of the MC/OC in situ. A better training response during the mid-cycle when the sessions are the most intense suggest an impact of the MC when the athletes approach their maximal capacity.

Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia

Sex differences in physiological responses to various stressors, including exercise, have been well documented. However, the specific impact of these differences on exposure to hypoxia, both at rest and during exercise, has remained underexplored. Many studies on the physiological responses to hypoxia have either excluded women or included only a limited number without analyzing sex-related differences. To address this gap, this comprehensive review conducted an extensive literature search to examine changes in physiological functions related to oxygen transport and consumption in hypoxic conditions. The review encompasses various aspects, including ventilatory responses, cardiovascular adjustments, hematological alterations, muscle metabolism shifts, and autonomic function modifications. Furthermore, it delves into the influence of sex hormones, which evolve throughout life, encompassing considerations related to the menstrual cycle and menopause. Among these physiological functions, the ventilatory response to exercise emerges as one of the most sex-sensitive factors that may modify reactions to hypoxia. While no significant sex-based differences were observed in cardiac hemodynamic changes during hypoxia, there is evidence of greater vascular reactivity in women, particularly at rest or when combined with exercise. Consequently, a diffusive mechanism appears to be implicated in sex-related variations in responses to hypoxia. Despite well-established sex disparities in hematological parameters, both acute and chronic hematological responses to hypoxia do not seem to differ significantly between sexes. However, it is important to note that these responses are sensitive to fluctuations in sex hormones, and further investigation is needed to elucidate the impact of the menstrual cycle and menopause on physiological responses to hypoxia.

The Influence of Menstrual Cycle Phases on Maximal Strength Performance in Healthy Female Adults: A Systematic Review with Meta-Analysis

Maximal strength is a significant factor in achieving peak performance and injury prevention in athletes. In individualization strategies for the efficient development of athletes, it is necessary to consider the respective components separately. The purpose of this study was to systematically examine the effects of the different cycle phases on isometric, isokinetic, and dynamic maximum strength. A systematic literature review was conducted; databases were searched from January 1960 to September 2023. The included studies focused on the expression of maximal strength in the earlier follicular phase as well as at least one comparative phase. Of the initial 707 articles identified, 22 met the selection criteria and were included. The studies considered a total of 433 subjects. Our results revealed medium effects (weighted mean standardized mean difference (SMD) = 0.60; seven studies) for isometric maximal strength in favor of the late follicular phase, small effects (weighted mean SMD = 0.39; five studies) for isokinetic maximal strength in favor of the ovulation phase, and small effects (weighted mean SMD = 0.14; three studies) for dynamic maximal strength in favor of the late follicular phase. The results indicate that the early follicular phase is unfavorable for all strength classes. Peak performance in isometric strength is seen in the late follicular phase, whereas isokinetic strength peaks during ovulation. Dynamic strength is optimal in the late follicular phase.

Higher rating of perceived exertion and lower perceived recovery following a graded exercise test during menses compared to non-bleeding days in untrained females

The underrepresentation of the female population in exercise sciences could be attributed, at least in part, to difficulty in appropriately accounting for the effects of the menstrual cycle (MC). Previous studies examining the effects of the MC on aerobic performance and subjective measures of aerobic performance show conflicting results. Purpose: The study examined how the MC affects the objective and subjective measures of aerobic performance within untrained female participants and in comparison with untrained male participants assessed at similar time intervals. Methods: Twenty-one participants (12 females and 9 males) completed a graded exercise test (GXT) on a cycle ergometer. The female participants were tested during their early follicular (EF; menses), ovulatory (O), and mid-luteal (ML) phases of the MC. The male participants were included as the control group and were randomly assigned to a menstrual cycle phase for each visit. During GXT, maximal oxygen consumption (VO2max), respiratory exchange ratio (RER), maximal heart rate (HRmax), peak blood lactate, and rating of perceived exertion (RPE) were determined. Twenty-four hours post-exercise, the perceived recovery status (PRS) was assessed. The MC phase was estimated using basal body temperature (BBT) in the female participants. Results: The male participants obtained a higher peak power and VO2max compared to the female participants (p < 0.05). All objective measures of aerobic performance did not significantly differ across the MC phases or time points that were tested. In the untrained female participants, an effect of the MC phase on RPE was found, with RPE being higher at EF (8.92 ± 0.79) compared to O (7.67 ± 1.23; p < 0.05) and ML (7.75 ± 1.06; p < 0.05). In addition, an effect of the MC phase on PRS was found, with perceived recovery being lower at EF (6.83 ± 0.94) compared to O (8.83 ± 1.12) and ML (8.67 ± 0.65; all p < 0.005) for the untrained female participants. No significant differences in RPE and PRS were found between tests in the untrained male participants. The female participants had lower perceived recovery following EF (6.83 ± 0.94) compared with the male participants (9.00 ± 1.00; p < 0.001). Conclusion: The untrained female participants perceived greater exertion during GXT and impaired recovery following GXT in EF compared to O and ML. These results may be attributed to either a drop in female sex hormone concentrations or discomfort associated with menses. The male participants did not exhibit any changes over time. Future studies using subjective parameters such as perceived exertion to track the internal load of training in the naturally menstruating female population should consider menses.

Effects of a training intervention tailored to the menstrual cycle on endurance performance and hemodynamics

BACKGROUND

This study aimed to compare the effects of block periodized training and training adapted to the menstrual cycle (MC) phases on endurance performance, cardiovascular parameters, recovery, and MC-related symptoms in active females.

METHODS

Fourteen naturally menstruating, moderately trained females (age: 24±3 years; BMI: 22.3±2.7) were randomized into an intervention (INT) and a control (CON) group. Throughout an 8-week intervention period, both groups participated in a polarized training program. In the INT, the training sessions were adapted to the MC with higher training loads within the mid and late follicular phase. Before and after the intervention maximal oxygen consumption (VO2max), velocity and heart rate at ventilatory thresholds one and two (vVT1, vVT2, hrVT1, hrVT2), systolic and diastolic blood pressure (sBP, dBP), root mean square of successive RR interval differences (RMSSD), standard deviation of NN intervals (SDNN), pulse wave velocity (PWV), and the premenstrual assessment form (PAF) were assessed.

RESULTS

There were no significant time × group interaction effects in all physiological parameters (VO2max: P=0.890; vVT1: P=1.000; hrVT1: P=0.464; vVT2: P=0.356; hrVT2: P=0.762 sBP: P=0.948; dBP: P=0.203; RMSSD: P=0.257; SDNN: P=0.241; PWV: P=0.818), or psychological parameters (PAF: P=0.745).

CONCLUSIONS

Tailoring a polarized training program to the MC did not augment training responses compared to a regular training program in active females. However, a substantial portion of the training intervention in the CON was coincidentally matched to the MC.

The Effect of Hormonal Contraceptive Use on Skeletal Muscle Hypertrophy, Power and Strength Adaptations to Resistance Exercise Training: A Systematic Review and Multilevel Meta-analysis

BACKGROUND

Resistance exercise training is widely used by general and athletic populations to increase skeletal muscle hypertrophy, power and strength. Endogenous sex hormones influence various bodily functions, including possibly exercise performance, and may influence adaptive changes in response to exercise training. Hormonal contraceptive (HC) use modulates the profile of endogenous sex hormones, and therefore, there is increasing interest in the impact, if any, of HC use on adaptive responses to resistance exercise training.

OBJECTIVE

Our aim is to provide a quantitative synthesis of the effect of HC use on skeletal muscle hypertrophy, power and strength adaptations in response to resistance exercise training.

METHODS

A systematic review with meta-analysis was conducted on experimental studies which directly compared skeletal muscle hypertrophy, power and strength adaptations following resistance exercise training in hormonal contraceptive users and non-users conducted before July 2023. The search using the online databases PUBMED, SPORTDiscus, Web of Science, Embase and other supplementary search strategies yielded 4669 articles, with 8 articles (54 effects and 325 participants) meeting the inclusion criteria. The methodological quality of the included studies was assessed using the "Tool for the assessment of study quality and reporting in exercise".

RESULTS

All included studies investigated the influence of oral contraceptive pills (OCP), with no study including participants using other forms of HC. The articles were analysed using a meta-analytic multilevel maximum likelihood estimator model. The results indicate that OCP use does not have a significant effect on hypertrophy [0.01, 95% confidence interval (CI) [- 0.11, 0.13], t = 0.14, p = 0.90), power (- 0.04, 95% CI [- 0.93, 0.84], t =  - 0.29, p = 0.80) or strength (0.10, 95% CI [- 0.08, 0.28], t = 1.48, p = 0.20).

DISCUSSION

Based on the present analysis, there is no evidence-based rationale to advocate for or against the use of OCPs in females partaking in resistance exercise training to increase hypertrophy, power and/or strength. Rather, an individualised approach considering an individual's response to OCPs, their reasons for use and menstrual cycle history may be more appropriate.

REGISTRATION

The review protocol was registered on PROSPERO (ID number and hyperlink: CRD42022365677).