Regulation of iron homeostasis by hepatocyte TfR1 requires HFE and contributes to hepcidin suppression in ß-thalassemia.

Transferrin receptor 1 (TfR1) performs a critical role in cellular iron uptake. Hepatocyte TfR1 is also proposed to influence systemic iron homeostasis by interacting with the hemochromatosis protein HFE to regulate hepcidin production. Here, we generated hepatocyte Tfrc knockout mice (Tfrcfl/fl;Alb-Cre+), either alone or together with Hfe knockout or ß-thalassemia, to investigate the extent to which hepatocyte TfR1 function depends on HFE, whether hepatocyte TfR1 impacts hepcidin regulation by serum iron and erythropoietic signals, and its contribution to hepcidin suppression and iron overload in ß-thalassemia. Compared with Tfrcfl/fl;Alb-Cre- controls, Tfrcfl/fl;Alb-Cre+ mice displayed reduced serum and liver iron; mildly reduced hematocrit, mean cell hemoglobin, and mean cell volume; increased erythropoietin and erythroferrone; and unchanged hepcidin levels that were inappropriately high relative to serum iron, liver iron, and erythroferrone levels. However, ablation of hepatocyte Tfrc had no impact on iron phenotype in Hfe knockout mice. Tfrcfl/fl;Alb-Cre+ mice also displayed a greater induction of hepcidin by serum iron compared with Tfrcfl/fl;Alb-Cre- controls. Finally, although acute erythropoietin injection similarly reduced hepcidin in Tfrcfl/fl;Alb-Cre+ and Tfrcfl/fl;Alb-Cre- mice, ablation of hepatocyte Tfrc in a mouse model of ß-thalassemia intermedia ameliorated hepcidin deficiency and liver iron loading. Together, our data suggest that the major nonredundant function of hepatocyte TfR1 in iron homeostasis is to interact with HFE to regulate hepcidin. This regulatory pathway is modulated by serum iron and contributes to hepcidin suppression and iron overload in murine ß-thalassemia.

BMP5 contributes to hepcidin regulation and systemic iron homeostasis in mice.

Hepcidin is the master regulator of systemic iron homeostasis. The bone morphogenetic protein (BMP) signaling pathway is a critical regulator of hepcidin expression in response to iron and erythropoietic drive. Although endothelial-derived BMP6 and BMP2 ligands have key functional roles as endogenous hepcidin regulators, both iron and erythropoietic drives still regulate hepcidin in mice lacking either or both ligands. Here, we used mice with an inactivating Bmp5 mutation (Bmp5se), either alone or together with a global or endothelial Bmp6 knockout, to investigate the functional role of BMP5 in hepcidin and systemic iron homeostasis regulation. We showed that Bmp5se-mutant mice exhibit hepcidin deficiency at age 10 days, blunted hepcidin induction in response to oral iron gavage, and mild liver iron loading when fed on a low- or high-iron diet. Loss of 1 or 2 functional Bmp5 alleles also leads to increased iron loading in Bmp6-heterozygous mice and more profound hemochromatosis in global or endothelial Bmp6-knockout mice. Moreover, double Bmp5- and Bmp6-mutant mice fail to induce hepcidin in response to long-term dietary iron loading. Finally, erythroferrone binds directly to BMP5 and inhibits BMP5 induction of hepcidin in vitro. Although erythropoietin suppresses hepcidin in Bmp5se-mutant mice, it fails to suppress hepcidin in double Bmp5- and Bmp6-mutant males. Together, these data demonstrate that BMP5 plays a functional role in hepcidin and iron homeostasis regulation, particularly under conditions in which BMP6 is limited.

Functional role of endothelial transferrin receptor 1 in iron sensing and homeostasis.

Systemic iron homeostasis is regulated by the hepatic hormone hepcidin to balance meeting iron requirements while limiting toxicity from iron excess. Iron-mediated induction of bone morphogenetic protein (BMP) 6 is a central mechanism for regulating hepcidin production. Liver endothelial cells (LECs) are the main source of endogenous BMP6, but how they sense iron to modulate BMP6 transcription and thereby hepcidin is uncertain. Here, we investigate the role of endothelial cell transferrin receptor 1 (TFR1) in iron uptake, BMP6 regulation, and systemic iron homeostasis using primary LEC cultures and endothelial Tfrc (encoding TFR1) knockout mice. We show that intracellular iron regulates Bmp6 expression in a cell-autonomous manner, and TFR1 mediates iron uptake and Bmp6 expression by holo-transferrin in primary LEC cultures. In addition, endothelial Tfrc knockout mice exhibit altered iron homeostasis compared with littermate controls when fed a limited iron diet, as evidenced by increased liver iron and inappropriately low Bmp6 and hepcidin expression relative to liver iron. However, endothelial Tfrc knockout mice have a similar iron phenotype compared to littermate controls when fed an iron-rich standard diet. Finally, ferritin and non-transferrin bound iron (NTBI) are additional sources of iron that mediate Bmp6 induction in primary LEC cultures via TFR1-independent mechanisms. Together, our data demonstrate a minor functional role for endothelial cell TFR1 in iron uptake, BMP6 regulation, and hepatocyte hepcidin regulation under iron limiting conditions, and suggest that ferritin and/or NTBI uptake by other transporters have a dominant role when iron availability is high.

Menstrual cycle affects iron homeostasis and hepcidin following interval running exercise in endurance-trained women.

PURPOSE: Menstrual cycle phase affects resting hepcidin levels, but such effects on the hepcidin response to exercise are still unclear. Thus, we investigated the hepcidin response to running during three different menstrual cycle phases. METHODS: Twenty-one endurance-trained eumenorrheic women performed three identical interval running protocols during the early-follicular phase (EFP), late-follicular phase (LFP), and mid-luteal phase (MLP). The protocol consisted of 8 × 3 min bouts at 85% of the maximal aerobic speed, with 90-s recovery. Blood samples were collected pre-exercise and at 0 h, 3 h and 24 h post-exercise. RESULTS: Data presented as mean ± SD. Ferritin were lower in the EFP than the LFP (34.82 ± 16.44 vs 40.90 ± 23.91 ng/ml, p = 0.003), while iron and transferrin saturation were lower during the EFP (58.04 ± 19.70 µg/dl, 14.71 ± 5.47%) compared to the LFP (88.67 ± 36.38 µg/dl, 22.22 ± 9.54%; p < 0.001) and the MLP (80.20 ± 42.05 µg/dl, 19.87 ± 10.37%; p = 0.024 and p = 0.045, respectively). Hepcidin was not affected by menstrual cycle (p = 0.052) or menstrual cycle*time interaction (p = 0.075). However, when comparing hepcidin at 3 h post-exercise, a moderate and meaningful effect size showed that hepcidin was higher in the LFP compared to the EFP (3.01 ± 4.16 vs 1.26 ± 1.25 nMol/l; d = 0.57, CI = 0.07-1.08). No effect of time on hepcidin during the EFP was found either (p = 0.426). CONCLUSION: The decrease in iron, ferritin and TSAT levels during the EFP may mislead the determination of iron status in eumenorrheic athletes. However, although the hepcidin response to exercise appears to be reduced in the EFP, it shows no clear differences between the phases of the menstrual cycle (clinicaltrials.gov: NCT04458662).

Influence of oral contraceptive phase on cardiorespiratory response to exercise in endurance-trained athletes.

OBJECTIVE: The aim of the study was to analyse the cardiorespiratory response to exercise during an oral contraceptive (OC) cycle in endurance-trained women. METHODS: Sixteen low-dose monophasic OC pill (OCP) users performed an interval-running protocol. The protocol consisted of eight 3 min bouts at 85% of participants' maximal aerobic speed (vV̇o2peak) with a 90s recovery at 30% vV̇o2peak in two OC phases: a withdrawal phase (WP) and an active pill phase (APP). The non-parametric Wilcoxon test was applied to analyse differences (p < 0.05) in performance variables between OC cycle phases. RESULTS: Throughout the high-intensity intervals, higher ventilation (WP 80.90 ± 11.49 L/min, APP 83.10 ± 13.33 L/min; p < 0.001) and relative perceived exertion (WP 14.51 ± 2.58, APP 15.11 ± 3.11; p = 0.001) during the APP were found, whereas carbon dioxide production (WP 2040.92 ± 262.93 mL/min, APP 2010.25 ± 305.68 mL/min; p = 0.003) was higher in the WP. During the active recovery intervals, ventilation (WP 65.78 ± 9.90 L/min, APP 67.88 ± 12.66 L/min; p < 0.001) was higher in the APP, while heart rate (WP 159.93 ± 10.26 bpm, APP 159.74 ± 12.83 bpm; p = 0.029) was higher in the WP. CONCLUSION: An increase in ventilation occurs during the APP, which is accompanied by higher perceived exertion. Therefore, coaches and athletes should be aware of these variations, especially perceived exertion, in regard to women's training programmes, in order to improve their performance, wellness and adherence to physical activity.

Physiological and pathophysiological mechanisms of hepcidin regulation: clinical implications for iron disorders.

The discovery of hepcidin has provided a solid foundation for understanding the mechanisms of systemic iron homeostasis and the aetiologies of iron disorders. Hepcidin assures the balance of circulating and stored iron levels for multiple physiological processes including oxygen transport and erythropoiesis, while limiting the toxicity of excess iron. The liver is the major site where regulatory signals from iron, erythropoietic drive and inflammation are integrated to control hepcidin production. Pathologically, hepcidin dysregulation by genetic inactivation, ineffective erythropoiesis, or inflammation leads to diseases of iron deficiency or overload such as iron-refractory iron-deficiency anaemia, anaemia of inflammation, iron-loading anaemias and hereditary haemochromatosis. In the present review, we discuss recent insights into the molecular mechanisms governing hepcidin regulation, how these pathways are disrupted in iron disorders, and how this knowledge is being used to develop novel diagnostic and therapeutic strategies.

Hepcidin response to interval running exercise is not affected by oral contraceptive phase in endurance-trained women.

The use of oral contraceptives (OCs) by female athletes may lead to improved iron status, possibly through the regulation of hepcidin by sex hormones. The present work investigates the response of hepcidin and interleukin-6 (IL-6) to an interval exercise in both phases of the OC cycle. Sixteen endurance-trained OC users (age 25.3 ± 4.7 years; height 162.4 ± 5.7 cm; body mass 56.0 ± 5.7 kg; body fat percentage 24.8 ± 6.0%; peak oxygen consumption [VO2peak ]: 47.4 ± 5.5 mL min-1 kg-1 ) followed an identical interval running protocol during the withdrawal and active pill phases of the OC cycle. This protocol consisted of 8 × 3 minutes bouts at 85% VO2peak speed with 90 seconds recovery intervals. Blood samples were collected pre-exercise, and at 0 hour, 3 hours, and 24 hours post-exercise. Pre-exercise 17ß-estradiol was lower (P = .001) during the active pill than the withdrawal phase (7.91 ± 1.81 vs 29.36 ± 6.45 pg/mL [mean ± SEM]). No differences were seen between the OC phases with respect to hepcidin or IL-6 concentrations, whether taking all time points together or separately. However, within the withdrawal phase, hepcidin concentrations were higher at 3 hours post-exercise (3.33 ± 0.95 nmol/L) than at pre-exercise (1.04 ± 0.20 nmol/L; P = .005) and 0 hour post-exercise (1.41 ± 0.38 nmol/L; P = .045). Within both OC phases, IL-6 was higher at 0 hour post-exercise than at any other time point (P < .05). Similar trends in hepcidin and IL-6 concentrations were seen at the different time points during both OC phases. OC use led to low 17ß-estradiol concentrations during the active pill phase but did not affect hepcidin. This does not, however, rule out estradiol affecting hepcidin levels.

Cardiorespiratory response to exercise in endurance-trained premenopausal and postmenopausal females.

PURPOSE: To assess the influence of different hormonal profiles on the cardiorespiratory response to exercise in endurance-trained females. METHODS: Forty-seven eumenorrheic females, 38 low-dose monophasic oral contraceptive (OC) users and 13 postmenopausal women, all of them endurance-trained, participated in this study. A DXA scan, blood sample tests and a maximal aerobic test were performed under similar low-sex hormone levels: early follicular phase for the eumenorrheic females; withdrawal phase for the OC group and at any time for postmenopausal women. Cardiorespiratory variables were measured at resting and throughout the maximal aerobic test (ventilatory threshold 1, 2 and peak values). Heart rate (HR) was continuously monitored with a 12-lead ECG. Blood pressure (BP) was measured with an auscultatory method and a calibrated mercury sphygmomanometer. Expired gases were measured breath-by-breath with the gas analyser Jaeger Oxycon Pro. RESULTS: One-way ANCOVA reported a lower peak HR in postmenopausal women (172.4 ± 11.7 bpm) than in eumenorrheic females (180.9 ± 10.6 bpm) (p = 0.024). In addition, postmenopausal women exhibited lower VO2 (39.1 ± 4.9 ml/kg/min) compared to eumenorrheic females (45.1 ± 4.4 ml/kg/min) in ventilatory threshold 2 (p = 0.009). Nonetheless, respiratory variables did not show differences between groups at peak values. Finally, no differences between OC users and eumenorrheic females' cardiorespiratory response were observed in endurance-trained females. CONCLUSIONS: Cardiorespiratory system is impaired in postmenopausal women due to physiological changes caused by age and sex hormones' decrement. Although these alterations appear not to be fully compensated by exercise, endurance training could effectively mitigate them. In addition, monophasic OC pills appear not to impact cardiorespiratory response to an incremental running test in endurance-trained females.

The Effect of the Oral Contraceptive Cycle Phase on Exercise-Induced Muscle Damage After Eccentric Exercise in Resistance-Trained Women.

ABSTRACT: Romero-Parra, N, Rael, B, Alfaro-Magallanes, VM, Janse de Jonge, X, Cupeiro, R, and Peinado, AB; On Behalf of the IronFEMME Study Group. The effect of the oral contraceptive cycle phase on exercise-induced muscle damage after eccentric exercise in resistance-trained women. J Strength Cond Res 35(2): 353-359, 2021-To evaluate the influence of the active pill phase versus withdrawal phase of a monophasic oral contraceptive (OC) cycle on exercise-induced muscle damage and inflammation after eccentric resistance exercise. Eighteen resistance-trained female OC users (age: 25.6 ± 4.2 years, height: 162.4 ± 5.0 cm, and body mass: 58.1 ± 5.7 kg) performed an eccentric squat-based exercise during the active pill phase and withdrawal phase of their OC cycle. Muscle soreness, counter movement jump (CMJ), and blood markers of muscle damage and inflammation were evaluated before and postexercise (0, 2, 24, and 48 hours). Creatine kinase (CK) values were higher in the withdrawal (181.8 ± 89.8 U·L-1) than in the active pill phase (144.0 ± 39.7 U·L-1) (p < 0.001). The highest CK concentrations and muscle soreness values were observed 24 hours postexercise (217.9 ± 117.5 U·L-1 and 44.7 ± 19.7, respectively) compared with baseline (115.3 ± 37.4 U·L-1 and 4.4 ± 9.2, respectively; p < 0.001). In addition, a decrease in CMJ immediately postexercise (20.23 ± 4.6 cm) was observed in comparison with baseline (24.2 ± 6.1 cm), which was not yet recovered 24 hours postexercise (21.9 ± 5.9 cm; p < 0.001). No other phase or time effects were observed. An eccentric squat-based exercise session elicits muscle damage but no inflammation response in resistance-trained women. Furthermore, the highest CK concentrations observed in the withdrawal phase suggest that this phase might be more vulnerable to muscle damage and, therefore, less adequate to administer high training loads. However, the lack of differences in other muscle damage variables between OC phases does not warrant any guidance on the active pill versus withdrawal phase.

Exercise-Induced Muscle Damage During the Menstrual Cycle: A Systematic Review and Meta-Analysis.

ABSTRACT: Romero-Parra, N, Cupeiro, R, Alfaro-Magallanes, VM, Rael, B, Rubio-Arias, JA, Peinado, AB, and Benito, PJ, IronFEMME Study Group. Exercise-induced muscle damage during the menstrual cycle: A systematic review and meta-analysis. J Strength Cond Res 35(2): 549-561, 2021-A strenuous bout of exercise could trigger damage of muscle tissue, and it is not clear how sex hormone fluctuations occurring during the menstrual cycle (MC) affect this response. The aims of this study were to systematically search and assess studies that have evaluated exercise-induced muscle damage (EIMD) in eumenorrheic women over the MC and to perform a meta-analysis to quantify which MC phases display the muscle damage response. The guidelines of the Preferred Reported Items for Systematic Reviews and Meta-Analysis were followed. A total of 19 articles were analyzed in the quantitative synthesis. Included studies examined EIMD in at least one phase of the following MC phases: early follicular phase (EFP), late follicular phase (LFP), or midluteal phase (MLP). The meta-analysis demonstrated differences between MC phases for delayed onset muscle soreness (DOMS) and strength loss (p < 0.05), whereas no differences were observed between MC phases for creatine kinase. The maximum mean differences between pre-excercise and post-exercise for DOMS were EFP: 6.57 (4.42, 8.71), LFP: 5.37 (2.10, 8.63), and MLP: 3.08 (2.22, 3.95), whereas for strength loss were EFP: -3.46 (-4.95, -1.98), LFP: -1.63 (-2.36, -0.89), and MLP: -0.72 (-1.07, -0.36) (p < 0.001). In conclusion, this meta-analysis suggests that hormone fluctuations throughout the MC affect EIMD in terms of DOMS and strength loss. Lower training loads or longer recovery periods could be considered in the EFP, when sex hormone concentrations are lower and women may be more vulnerable to muscle damage, whereas strength conditioning loads could be enhanced in the MLP.

Serum iron availability, but not iron stores, is lower in naturally menstruating than in oral contraceptive athletes.

This study measured serum markers of iron status in naturally menstruating and oral contraceptive (OC) athletes during the main hormonal milieus of these two profiles to identify potential differences confounding the diagnosis of iron deficiency in female athletes. Resting blood samples were collected from 36 naturally menstruating athletes during the early-follicular phase (EFP), mid- late-follicular phase (MLFP) and mid-luteal phase (MLP) of the menstrual cycle. Simultaneously, blood samples were collected from 24 OC athletes during the withdrawal and active-pill phase of the OC cycle. Serum iron, ferritin, transferrin, transferrin saturation (TSAT), C-reactive protein (CRP), interleukin-6 and sex hormones were analyzed. Naturally menstruating athletes showed lower levels of TSAT, iron and transferrin than OC athletes when comparing the bleeding phase of both profiles (p<0.05) as well as when comparing all analyzed phases of the menstrual cycle to the active pill phase of the OC cycle (p<0.05). Interestingly, only lower transferrin was found during MLFP and MLP compared to the withdrawal phase of the OC cycle (p>0.05), with all other iron markers showing no differences (p>0.05). Intracycle variations were also found within both types of cycle, presenting reduced TSAT and iron during menstrual bleeding phases (p<0.05). In conclusion, in OC athletes, serum iron availability, but not serum ferritin, seems higher than in naturally menstruating ones. However, such differences are lost when comparing the MLFP and MLP of the menstrual cycle with the withdrawal phase of the OC cycle. This should be considered in the assessment of iron status in female athletes.Highlights Naturally menstruating athletes present lower TSAT, iron and transferrin in all analyzed phases of the menstrual cycle compared to OC athletes during their active pill phase. However, both the mid-late follicular and mid-luteal phases of the menstrual cycle do not differ from the withdrawal phase of the oral contraceptive cycle.Intracycle variations are found for TSAT and iron in both naturally menstruating and oral contraceptive athletes, which are mainly driven by a reduction in TSAT and iron during menstrual bleeding phases.As serum iron availability changes significantly as a function of the athlete's hormonal status, it should be considered in the assessment of the athlete's iron status as well as standardise the phase of the menstrual cycle in which to assess iron markers to avoid misdiagnosis or misleading results.In contrast, the assessment of iron stores through serum ferritin is substantially stable and the athlete's hormonal status does not seem to be of relevance for this purpose.

Effect of Menstrual Cycle Phase on the Recovery Process of High-Intensity Interval Exercise-A Cross-Sectional Observational Study.

Although the study of the menstrual cycle influence on endurance exercise has recently increased, there is a lack of literature studying its influence on females' cardiorespiratory recovery. Thus, the aim of the present work was to assess menstrual cycle influence on post-exercise recovery following a high intensity interval exercise in trained females. Thirteen eumenorrheic endurance-trained females performed an interval running protocol in three menstrual cycle phases: early follicular phase (EFP), late follicular phase (LFP), and mid-luteal phase (MLP). The protocol consisted of 8 × 3-min bouts at 85% of their maximal aerobic speed (vVO2peak) with a 90-s rest between bouts and a final 5-min active recovery at 30% vVO2peak. All variables were averaged every 15 s, obtaining 19 moments during recovery (time factor). To analyze the effects of the menstrual cycle on the final active cardiorespiratory recovery, an ANOVA for repeated measures was performed. ANOVA showed an effect on menstrual cycle phase on ventilation (EFP: 1.27 ± 0.35; LFP: 1.19 ± 0.36; MLP: 1.27 ± 0.37), breathing frequency (EFP: 35.14 ± 7.14; LFP: 36.32 ± 7.11; MLP: 37.62 ± 7.23), and carbon dioxide production (EFP: 1120.46 ± 137.62; LFP: 1079.50 ± 129.57; MLP: 1148.78 ± 107.91). Regarding the interaction results (phase x time), ventilation is higher at many of the recovery times during the MLP, with less frequent differences between EFP and LFP (F = 1.586; p = 0.019), while breathing reserve is lower at many of the recovery times during MLP, with less time differences between EFP and LFP (F = 1.643; p = 0.013). It seems that the menstrual cycle affects post-exercise recovery specially during the MLP, rising ventilation and lowering breathing reserve, giving rise to an impaired ventilatory efficiency.

Influence of sex hormones status and type of training on regional bone mineral density in exercising females.

The primary objective of this study was to examine the influence of hormonal ovarian profile and training characteristics on spine, pelvis, and total body bone mineral density (BMD) in a group of well-trained females. Forty-two eumenorrheic females, twenty-eight monophasic oral contraceptive (OC) users and thirteen postmenopausal females participated in this study. Body composition was measured by total body dual-energy X-ray absorptiometry (DXA) to determine BMD of the areas of interest. Endurance-trained premenopausal females showed lower spine BMD compared to resistance-trained premenopausal females (1.03 ± 0.1 vs. 1.09 ± 0.09 g/cm2; p = 0.025). Postmenopausal females reported lower BMD level in comparison to eumenorrheic females in pelvis (1.079 ± 0.082 vs 1.19 ± 0.115 g/cm2; p = 0.005), spine (0.969 ± 0.097 vs 1.069 ± 0.109 g/cm2; p = 0.012) and total (1.122 ± 0.08 vs 1.193 ± 0.077 g/cm2; p = 0.018) and OC users whose duration of OC use was less than 5 years (OC < 5) in pelvis (1.235 ± 0.068 g/cm2; p < 0.001) and spine (1.062 ± 0.069 g/cm2; p = 0.018). In addition, lower BMD values were found in OC users who had been using OC for more than 5 years (OC ≥ 5) than eumenorrheic females in pelvis (1.078 ± 0.086 g/cm2; p = 0.029) and spine (0.966 ± 0.08 g/cm2; p = 0.05). Likewise, OC ≥ 5 showed lower values than and OC < 5 in pelvis (p = 0.004) and spine (p = 0.047). We observed a lower spine BMD value in premenopausal endurance-trained females compared to premenopausal resistance-trained females. Moreover, this research observed that prolonged use of OCs may reduce bone mass acquisition in the spine and pelvis, even in well-trained females. Finally, postmenopausal showed lower BMD despite being exercising women.Trial registration: ClinicalTrials.gov identifier: NCT04458662.Highlights Ovarian hormonal profile should be considered when assessing BMD in female athletes.The duration of oral contraceptive use influences spine and pelvis regional BMD in exercising females.Postmenopausal women show lower BMD when compared to premenopausal females despite being exercising females.

Hepcidin and interleukin-6 responses to endurance exercise over the menstrual cycle.

The aim of the current study was to investigate iron metabolism in endurance trained women through the interleukin-6, hepcidin and iron responses to exercise along different endogenous hormonal states. Fifteen women performed 40 min treadmill running trials at 75% vVO2peak during three specific phases of the menstrual cycle: early follicular phase (day 3 ± 0.85), mid-follicular phase (day 8 ± 1.09) and luteal phase (day 21 ± 1.87). Venous blood samples were taken pre-, 0 h post- and 3 h post-exercise. Interleukin-6 reported a significant interaction for menstrual cycle phase and time (p=0.014), showing higher interleukin-6 levels at 3 h post-exercise during luteal phase compared to the early follicular phase (p=0.004) and the mid-follicular phase (p=0.002). Iron levels were significantly lower (p=0.009) during the early follicular phase compared to the mid-follicular phase. However, hepcidin levels were not different across menstrual cycle phases (p>0.05). The time-course for hepcidin and interleukin-6 responses to exercise was different from the literature, since hepcidin peak levels occurred at 0 h post-exercise, whereas the highest interleukin-6 levels occurred at 3 h post-exercise. We concluded that menstrual cycle phases may alter interleukin-6 production causing a higher inflammation when progesterone levels are elevated (days 19-21). Moreover, during the early follicular phase a significant reduction of iron levels is observed potentially due to a loss of haemoglobin through menses. According to our results, high intensity exercises should be carefully monitored in these phases in order not to further compromise iron stores.

Body Composition Over the Menstrual and Oral Contraceptive Cycle in Trained Females.

PURPOSE: The influence of female sex hormones on body fluid regulation and metabolism homeostasis has been widely studied. However, it remains unclear whether hormone fluctuations throughout the menstrual cycle (MC) and with oral contraceptive (OC) use affect body composition (BC). Thus, the aim of this study was to investigate BC over the MC and OC cycle in well-trained females. METHODS: A total of 52 eumenorrheic and 33 monophasic OC-taking well-trained females participated in this study. Several BC variables were measured through bioelectrical impedance analysis 3 times in the eumenorrheic group (early follicular phase, late follicular phase, and midluteal phase) and on 2 occasions in the OC group (withdrawal phase and active pill phase). RESULTS: Mixed linear model tests reported no significant differences in the BC variables (body weight, body mass index, basal metabolism, fat mass, fat-free mass, and total body water) between the MC phases or between the OC phases (P > .05 for all comparisons). Trivial and small effect sizes were found for all BC variables when comparing the MC phases in eumenorrheic females, as well as for the OC cycle phases. CONCLUSIONS: According to the results, sex hormone fluctuations throughout the menstrual and OC cycle do not influence BC variables measured by bioelectrical impedance in well-trained females. Therefore, it seems that bioimpedance analysis can be conducted at any moment of the cycle, both for eumenorrheic women and women using OC.

Exercise-Induced Muscle Damage in Postmenopausal Well-Trained Women.

BACKGROUND: Sex hormone deprivation derived from menopause may affect exercise-induced muscle damage (EIMD). No studies have previously evaluated this response between postmpenopausal and premenopausal eumenorrheic women over the menstrual cycle. HYPOTHESIS: Postmenopausal women will present higher EIMD markers than premenopausal women, especially in comparison with the menstrual cycle phases where sex hormone concentrations are higher. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Thirteen postmenopausal and 19 eumenorrheic women, all of them resistance-trained, performed an eccentric squat-based exercise. The postmenopausal group performed 1 bout of exercise, while the eumenorrheic group performed 3 bouts coinciding with the early follicular, late follicular, and mid-luteal phases ot their menstrual cycle. Muscle soreness, countermovement jump, creatine kinase (CK), myoglobin, lactate dehydrogenase, interleukin-6, tumor necrosis factor-α, and C-reactive protein were evaluated before and postexercise. RESULTS: The expected differences in sex hormones were observed between groups (P < 0.001) according to their reproductive status. Postexercise increases in CK, myoglobin, and muscle soreness (168.2 ± 45.5 U/L, 123.1 ± 41.5 µg/L, and 20.7 ± 21.3 mm, respectively) were observed in comparison with baseline (136.2 ± 45.5 U/L, 76.9 ± 13.8 µg/L, and 2.7 ± 4.2 mm, respectively). Myoglobin values at baseline in postmenopausal women were higher compared with premenopausal women in the aforementioned menstrual cycle phases, respectively (62.8 ± 8.2, 60.4 ± 7.2, and 60.1 ± 10.6 µg/L; P < 0.001 for all comparisons), which was supported by large effect sizes (0.72-1.08 standardized d units). No postexercise differences were observed between groups in any markers (P > 0.05). CONCLUSION: Despite higher resting levels of myoglobin and lower strength values in postmenopausal than in premenopausal women, EIMD was similar between both reproductive profiles. This suggests a potential benefit of being physically active despite aging and sex hormone deprivation. CLINICAL RELEVANCE: Sex hormone deprivation derived from menopause seems not to influence muscle damage reponse to eccentric exercise in resistance-trained postmenopausal women.

Menstrual Cycle Phases Influence on Cardiorespiratory Response to Exercise in Endurance-Trained Females.

The aim of this study was to analyse the impact of sex hormone fluctuations throughout the menstrual cycle on cardiorespiratory response to high-intensity interval exercise in athletes. Twenty-one eumenorrheic endurance-trained females performed an interval running protocol in three menstrual cycle phases: early-follicular phase (EFP), late-follicular phase (LFP) and mid-luteal phase (MLP). It consisted of 8 × 3-min bouts at 85% of their maximal aerobic speed with 90-s recovery at 30% of their maximal aerobic speed. To verify menstrual cycle phase, we applied a three-step method: calendar-based counting, urinary luteinizing hormone measurement and serum hormone analysis. Mixed-linear model for repeated measures showed menstrual cycle impact on ventilatory (EFP: 78.61 ± 11.09; LFP: 76.45 ± 11.37; MLP: 78.59 ± 13.43) and heart rate (EFP: 167.29 ± 11.44; LFP: 169.89 ± 10.62; MLP: 169.89 ± 11.35) response to high-intensity interval exercise (F2.59 = 4.300; p = 0.018 and F2.61 = 4.648; p = 0.013, respectively). Oxygen consumption, carbon dioxide production, respiratory exchange ratio, breathing frequency, energy expenditure, relative perceived exertion and perceived readiness were unaltered by menstrual cycle phase. Most of the cardiorespiratory variables measured appear to be impassive by menstrual cycle phases throughout a high-intensity interval exercise in endurance-trained athletes. It seems that sex hormone fluctuations throughout the menstrual cycle are not high enough to disrupt tissues' adjustments caused by the high-intensity exercise. Nevertheless, HR based training programs should consider menstrual cycle phase.

Effect of Different Types of Face Masks on the Ventilatory and Cardiovascular Response to Maximal-Intensity Exercise.

The development of new models of face masks makes it necessary to compare their impact on exercise. Therefore, the aim of this work was to compare the cardiopulmonary response to a maximal incremental test, perceived ventilation, exertion, and comfort using FFP2 or Emotion masks in young female athletes. Thirteen healthy sportswomen (22.08 ± 1.75 years) performed a spirometry, and a graded exercise test on a treadmill, with a JAEGER® Vyntus CPX gas analyzer using an ergospirometry mask (ErgoMask) or wearing the FFP2 or the Emotion mask below the ErgoMask, randomized on 3 consecutive days. Also, menstrual cycle status was monitored to avoid possible intrasubject alterations. The results showed lower values for the ErgoMask+FFP2, compared to ErgoMask or ErgoMask+Emotion, in forced vital capacity (3.8 ± 0.2, 4.5 ± 0.2 and 4.1 ± 0.1 l, respectively); forced expiratory volume in 1 s (3.3 ± 0.2, 3.7 ± 0.2 and 3.5 ± 0.1 l); ventilation (40.9 ± 1.5, 50.6 ± 1.5 and 46.9 ± 1.2 l/min); breathing frequency (32.7 ± 1.1, 37.4 ± 1.1 and 35.3 ± 1.4 bpm); VE/VO2 (30.5 ± 0.7, 34.6 ± 0.9 and 33.6 ± 0.7); VE/VCO2 (32.2 ± 0.6, 36.2 ± 0.9 and 34.4 ± 0.7) and time to exhaustion (492.4 ± 9.7, 521.7 ± 8.6 and 520.1 ± 9.5 s) and higher values in inspiratory time (0.99 ± 0.04, 0.82 ± 0.03 and 0.88 ± 0.03 s). In conclusion, in young healthy female athletes, the Emotion showed better preservation of cardiopulmonary responses than the FFP2.

Methodological Approach of the Iron and Muscular Damage: Female Metabolism and Menstrual Cycle during Exercise Project (IronFEMME Study).

Background: The increase in exercise levels in the last few years among professional and recreational female athletes has led to an increased scientific interest about sports health and performance in the female athlete population. The purpose of the IronFEMME Study described in this protocol article is to determine the influence of different hormonal profiles on iron metabolism in response to endurance exercise, and the main markers of muscle damage in response to resistance exercise; both in eumenorrheic, oral contraceptive (OC) users and postmenopausal well-trained women. Methods: This project is an observational controlled randomized counterbalanced study. One hundered and four (104) active and healthy women were selected to participate in the IronFEMME Study, 57 of which were eumenorrheic, 31 OC users and 16 postmenopausal. The project consisted of two sections carried out at the same time: iron metabolism (study I) and muscle damage (study II). For the study I, the exercise protocol consisted of an interval running test (eight bouts of 3 min at 85% of the maximal aerobic speed), whereas the study II protocol was an eccentric-based resistance exercise protocol (10 sets of 10 repetitions of plate-loaded barbell parallel back squats at 60% of their one repetition maximum (1RM) with 2 min of recovery between sets). In both studies, eumenorrheic participants were evaluated at three specific moments of the menstrual cycle: early-follicular phase, late-follicular phase and mid-luteal phase; OC users performed the trial at two moments: withdrawal phase and active pill phase. Lastly, postmenopausal women were only tested once, since their hormonal status does not fluctuate. The three-step method was used to verify the menstrual cycle phase: calendar counting, blood test confirmation, and urine-based ovulation kits. Blood samples were obtained to measure sex hormones, iron metabolism parameters, and muscle damage related markers. Discussion: IronFEMME Study has been designed to increase the knowledge regarding the influence of sex hormones on some aspects of the exercise-related female physiology. Iron metabolism and exercise-induced muscle damage will be studied considering the different reproductive status present throughout well-trained females' lifespan.