Effect Of Menstrual Cycle Phase Research Articles

Content matters: Cyclic effects on women's voices depend on social context

Women's voices reportedly sound more attractive during the fertile days compared to the non-fertile days of their menstrual cycle. Here we investigated whether the speech content modulates the cyclic changes in women's voices. We asked 72 men and women to rate how interested they were in getting to know the speaker based on her voice. Forty-two naturally cycling women were recorded once during the late follicular phase (high fertility) and once during the luteal phase (low fertility) while speaking sentences of neutral and social content. Listeners were more interested in getting to know the speakers when hearing sentences with social content. Furthermore, raters were more interested in getting to know the speakers when these were recorded in the late follicular than in the luteal phase, but only in sentences with social content. Notably, levels of reproductive hormones (EP ratio) across the cycle phases did not significantly predict the preference for late follicular voices, but echoing the perceptual ratings, there was a significant EP ratio x speech content interaction. Phonetic analyses of mean fundamental frequency (F0) revealed a main effect of menstrual cycle phase and speech content but no interaction. Employing an action-oriented task, the present study extends findings of cycle-dependent voice changes by emphasising that speech content critically modulates fertility effects.

Physical, Biochemical, and Neuromuscular Responses to Repeated Sprint Exercise in Eumenorrheic Female Handball Players: Effect of Menstrual Cycle Phases.

Graja, A, Kacem, M, Hammouda, O, Borji, R, Bouzid, MA, Souissi, N, and Rebai, H. Physical, biochemical, and neuromuscular responses to repeated sprint exercise in eumenorrheic female handball players: effect of menstrual cycle phases. J Strength Cond Res 36(8): 2268-2276, 2022-Very few studies have been interested in the relationship between ovarian hormones and physiological function in female athletes. The aim of this study was to assess the effect of menstrual phases (MP) on physical, neuromuscular, and biochemical responses after repeated sprint exercise (RSE) in female handball players. Ten eumenorrheic athletes (22.5 ± 1.5 years, 1.70 ± 0.04 m) participated in 3 study visits (follicular phase [FP], luteal phase [LP], and premenstrual phase [PMP]). During each MP, they performed 20 × 5-second cycle sprints interspersed with 25 seconds of rest. Maximal voluntary contraction (MVC) tests of the knee extensor muscles at 90° of knee flexion were performed before and after RSE. Peak force and electromyography (EMG) signals were measured during the MVC tests. Blood samples were collected before and 3 minutes after each session. The percentage of decrement in peak power output over the 20 × 5-second cycle test (i.e., fatigue index) calculated between sprints 1 and 20 decreased significantly during PMP (-43.3% ± 5.7%) but not in LP (-39.2% ± 7.7%) compared with FP (-32.44% ± 6.3%) ( p < 0.05). Moreover, no significant difference was found between MP in all frequency components of EMG before RSE ( p > 0.05). Maximal voluntary contraction, neuromuscular efficiency, and median frequency values of vastus lateralis and rectus femoris were significantly decreased in PMP compared with FP and LP ( p < 0.05). Creatine kinase (CK) levels were significantly higher in PMP compared with FP and LP after RSE ( p < 0.05). These findings suggest that RSE induces more peripheral fatigue associated with muscle damage in PMP. This might be attributable to hormonal variation across MP. Therefore, FP seems to be the right time for intense training to improve strength performance.

Influence of the Menstrual Cycle on Blood Markers of Muscle Damage and Inflammation Following Eccentric Exercise.

The aim of this study was to evaluate whether the menstrual cycle and its underlying hormonal fluctuations affect muscle damage and inflammation in well-trained females following an eccentric exercise. Nineteen eumenorrheic women performed an eccentric squat-based exercise in the early follicular phase, late follicular phase and mid-luteal phase of their menstrual cycle. Sex hormones and blood markers of muscle damage and inflammation –creatine kinase, myoglobin, lactate dehydrogenase, interleukin-6, tumoral necrosis factor-α, and C reactive protein– were analyzed in each phase. No effect of menstrual cycle phase was observed (p > 0.05), while an interaction for interleukin-6 was shown (p = 0.047). Accordingly, a moderate effect size [0.68 (0.53)–0.84 (0.74)], indicated that interleukin-6 values 2 h post-trial (2.07 ± 1.26 pg/mL) were likely to be higher than baseline (1.59 ± 0.33 pg/mL), 24 h (1.50 ± 0.01 pg/mL) and 48 h (1.54 ± 0.13 pg/mL) in the mid-luteal phase. Blood markers of muscle damage and inflammation were not affected by the menstrual cycle in well-trained women. The eccentric exercise barely triggered muscle damage and hence, no inflammation was observed, possibly due to participants training status. The mid-luteal phase was the only phase reflecting a possible inflammatory response in terms of interleukin-6, although further factors than sex hormones seem to be responsible for this finding.

The effect of the menstrual cycle on running economy.

The aim of this study was to examine the effect of the menstrual cycle on running economy (RE). Using a repeated-measures design, ten eumenorrheic, trained female runners (age: 32±6 yrs, V̇O2max: 59.7±4.7 mL·kg-1·min-1) completed four, weekly, identical sub-maximal and maximal incremental step tests on a treadmill to measure physiological responses across a full menstrual cycle. For phase comparison, the results from the trials that fell in the early follicular (low estrogen, low progesterone), late follicular (high estrogen, low progesterone) and mid-luteal (high estrogen, high progesterone) phases were used. There was a significant effect of menstrual cycle phase on RE (P=0.001), with RE in the mid-luteal (ML) phase being worse than that of the early follicular (EF) (+2.33 mL·kg-1·min-1; P=0.026) and late follicular (LF) (+2.17 mL·kg-1·min-1; P=0.011) phases. The ML phase also resulted in elevated core temperature versus the EF (+0.51 ºC; P=0.001) and LF (+0.66 ºC; P=0.037) phases, and elevated minute ventilation versus the EF phase (+3.83 L·min-1; P=0.003). No significant effects of menstrual cycle phase were found on body mass, heart rate, ratings of perceived exertion, time-to-exhaustion, maximal oxygen consumption, or blood lactate concentration. In the ML phase, which causes increased core temperature and minute ventilation, RE is impaired at exercise intensities that are applicable to training and performance. In physiologically stressful environments, this impairment in RE may have a significant impact on training and performance.

The effect of menstrual cycle on maximal breath-hold time

This study investigated the effect of menstrual cycle phase on breath-hold time (BHT). Twelve healthy females, aged 18–30 yrs, with regular menstrual cycles, without breath-hold (BH) experience, performed a BH protocol which included eight repeated maximal efforts with face immersion in cool water separated by 2-min intervals in two different phases of menstrual cycle; early follicular (EF) phase and midluteal (ML) phase. Respiratory, cardiovascular and hematological responses were studied before, during and after BH efforts. Maximal BHT was significantly higher during ML (115.59 ± 13.95 s) compared to EF (106.10 ± 12.42 s) phase of the menstrual cycle. Metabolic rate and build-up of CO2 were higher (p < 0.001) in EF compared to ML phase. In conclusion, the greater BHT observed at the ML phase of the menstrual cycle may be the result of elevated levels of estrogen and progesterone during midluteal phase affecting both ventilatory response and metabolic rate.

Effects of menstrual cycle phases on preoperative anxiety: A randomized prospective observational trial

Effects of menstrual cycle phases on preoperative anxiety: A randomized prospective observational trial

Influence of Peak Menstrual Cycle Hormonal Changes on Restoration of Fluid Balance After Induced Dehydration.

The present study examined the impact of hormonal differences between late follicular (LF) and midluteal (ML) phases on restoration of fluid balance following dehydration. Ten eumenorrheic female participants were dehydrated by 2% of their body mass through overnight fluid restriction followed by exercise-heat stress. Trials were undertaken during the LF (between Days 10 and 13 of the menstrual cycle) and ML phases (between Days 18 and 23 of the menstrual cycle) with one phase repeated to assess reliability of observations. Following dehydration, participants ingested a volume equivalent to 100% of mass loss of a commercially available sports drink in four equal volumes over 30min. Mean serum values for steroid hormones during the ML (estradiol [E2]: 92 ± 11pg/ml, progesterone: 19 ± 4ng/ml) and LF (estradiol [E2]: 232 ± 64pg/ml, progesterone: 3 ± 2ng/ml) were significantly different between phases. Urine tests confirmed no luteinizing hormone surge evident during LF trials. There was no effect of menstrual cycle phase on cumulative urine volume during the 3-hr rehydration period (ML: 630 [197-935]ml, LF: 649 [180-845]ml) with percentage of fluid retained being 47% (33-85)% on ML and 46% (37-89)% on LF (p = .29). There was no association between the progesterone:estradiol ratio and fluid retained in either phase. Net fluid balance, urine osmolality, and thirst intensity were not different between phases. No differences in sodium (ML: -61 [-36 to -131]mmol, LF: -73 [-5 to -118]mmol; p = .45) or potassium (ML: -36 [-11 to -80]mmol, LF: -30 [-19 to -89]mmol; p = .96) balance were observed. Fluid replacement after dehydration does not appear to be affected by normal hormonal fluctuations during the menstrual cycle in eumenorrheic young women.

The Effect of Menstrual Cycle Phase and Hormonal Contraceptive Use on Post-concussive Symptom Reporting in Non-concussed Adults

Post-concussion symptoms are notoriously non-specific and overlap with menstrual symptoms. The goal of the present study was to investigate the relationship between symptoms at different points in the menstrual cycle. Forty-four females, 23 who used hormonal contraceptives, and 34 males completed the Post-Concussive Symptom Scale (PCSS) and the Depression, Anxiety, and Stress Scale on two occasions. There were substantial group differences with regard to test-retest reliability and agreement, with unacceptably low reliability on the PCSS for females on hormonal birth control. Eumenorrheic females had systematic changes in individual symptoms, whereas females taking hormonal contraceptives showed no differences over time. The results highlight the importance of considering hormonal influences in the assessment of post-concussion and psychiatric symptoms in females post-injury.

Capacity to Compensate for Central Hypovolemia and Effects of Menstrual Cycle Phases.

BACKGROUND: Tolerance to central hypovolemia is dictated by exhaustion of the physiological capacity to compensate called the compensatory reserve. Such physiological compromise can have detrimental impact on performance in aerospace environments as well as survival from hemorrhage on the battlefield. We induced central hypovolemia using progressively stepwise lower body negative pressure (LBNP) in women during various phases of the menstrual cycle to test the hypothesis that similar tolerance across all menstrual cycle phases would be reflected by similar changes in compensatory reserve.METHODS: Based on self-reporting of the last menstrual period, 40 healthy women, matched by demographics, were classified into 1 of 5 menstrual cycle phases: early follicular (EF, Days 1-7; N = 10), late follicular and ovulatory (LF, Days 9-15, N = 6), early luteal (EL, Days 16-18, N = 6), midluteal (ML, Days 19-25, N = 8), and late luteal (LL, Days 26-30, N = 10). All subjects had a 28-30 d menstrual cycle and were not taking oral contraceptives. Tolerance to central hypovolemia was measured as time (seconds) from baseline to the onset of presyncopal symptoms induced by LBNP.RESULTS: Time to presyncope as well as hemodynamic and compensatory reserve responses were statistically indistinguishable across all menstrual cycle phases.DISCUSSION: Consistent with our hypothesis, compensatory reserve with associated hemodynamic responses and tolerance to central hypovolemia was not affected by menstrual cycle phases. Our findings indicate experimental comparisons of responses to central hypovolemia involving the participation of healthy women with normal menstrual cycles and not taking oral contraceptives can be conducted independent of menstrual cycle phase.Convertino VA, Schlotman TE, Stacey W, Hinojosa-Laborde C. Capacity to compensate for central hypovolemia and effects of menstrual cycle phases. Aerosp Med Hum Perform. 2019; 90(4):378-383.

Effect of the Menstrual Cycle on Vasodilatory Responses to Standard and Enhanced Flow‐ Mediated Dilation Stimuli

Flow‐mediated dilation (FMD) is a clinical index of endothelial health that has not revealed consistent differences between the sexes or the phases of the menstrual cycle, both of which are known to affect endothelial function. Since estradiol varies with the menstrual cycle and up‐regulates nitric oxide, a primary mediator of the FMD response, it is surprising that past studies have not revealed consistent associations between FMD and menstrual cycle phase. It may be that the standard FMD is not sensitive enough to reflect the subtle changes in endothelial function which occur across the menstrual cycle. Recent data suggest that enhanced FMD stimuli provide a potential means for detecting subtle changes in endothelial function that are not observed using the standard FMD. We hypothesized that an enhanced FMD stimulus, as elicited by 3 min of forearm occlusion concomitant with isometric handgrip exercise at 30% of maximal voluntary contraction (IEFMD), will be more responsive to menstrual cycle‐induced changes in estradiol (and therefore vasodilatory responsiveness) than the standard 5‐min FMD in young healthy women. We compared reactive hyperemic responses (%FMD) between FMD protocols (i.e. standard FMD vs. IEFMD) in eumenorrheic women (n: 4; age: 21±1.4 yrs, range: 19–22 yrs, BMI: 23.3±3.2 kg/m2, range: 20.5–26.4 kg/m2, cycle length: 29.8±1.7 days, range: 28–32 days) during the low‐estradiol early follicular phase of the menstrual cycle (EF; days 1–5) and the high‐estradiol late follicular phase (LF; days 10–14). As expected, we observed a greater %FMD in response to the IEFMD relative to the standard FMD in the EF phase (19.4±4.6% vs. 9.0±1.6% respectively, p&lt;0.05). Similarly, in the LF phase we observed a trend toward a greater %FMD in the IEFMD versus the standard FMD (13.5±5.8% vs. 7.0±0.04%, p=0.1). However, a two‐way ANOVA demonstrated no main effect of menstrual cycle phase (p=0.5), or FMD stimulus (p=0.7) on %FMD (phase x stimulus interaction: p=0.9). Therefore, these preliminary data do not support our hypothesis that an enhanced FMD stimulus involving isometric handgrip exercise is more sensitive than the standard FMD in detecting changes in endothelial function across menstrual cycle phases in young healthy women.Support or Funding InformationThis project was supported by a Natural Sciences and Engineering Research Council Discovery Grant (CWU). TEA &amp; YC were supported by the McGill Department of Kinesiology and Physical Education Graduate Excellence Fellowship.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sex differences in cerebral autoregulation are unaffected by menstrual cycle phase in young, healthy women.

Sex is known to affect the prevalence of conditions such as stroke. However, effects of sex on cerebral blood flow regulation are still not well understood. Critical to this understanding is how fluctuations in hormones across the menstrual cycle affect cerebral autoregulation. We measured autoregulation in the early follicular, late follicular, and midluteal phases during spontaneous and induced blood pressure oscillations in 26 young, healthy individuals (13 women and 13 men, age: 26 ± 4 yr). Men participated three times, ~1-3 wk apart. Beat-by-beat blood pressure, heart rate, end-tidal CO2, and transcranial Doppler ultrasonography of the middle (MCA) and anterior (ACA) cerebral arteries were obtained. We did not find a difference in cerebral autoregulation across the menstrual cycle in women but found significantly improved autoregulation in the MCA and ACA of women compared with men. Women demonstrated significantly lower MCA gain (0.97 ± 0.13 vs. 1.17 ± 0.14%/mmHg, P = 0.001), higher MCA phase (46.1 ± 12.6 vs. 35.8 ± 7.9°, P = 0.019), and higher ACA phase (40.5 ± 10.8 vs 31.5 ± 8.5°, P = 0.040) during repeated squat-to-stand maneuvers. Women also had lower MCA gain (1.50 ± 0.11 vs. 1.72 ± 0.30%/mmHg, P = 0.029) during spontaneous fluctuations in pressure while standing and less of a decrease in MCA flow velocity (-18.7 ± 2.7 vs. -23.2 ± 6.0%, P = 0.014) during sit-to-stand maneuvers. Our results suggest that young women have improved cerebral autoregulation compared with young men regardless of menstrual cycle phase and that autoregulation is relatively robust to acute fluctuations in female sex hormones. NEW & NOTEWORTHY This is the first study to investigate thoroughly the effects of menstrual cycle phase and sex differences in cerebral autoregulation in young, healthy individuals. Cerebral autoregulation was unaffected by menstrual cycle phase during both repeated squat-to-stand and sit-to-stand maneuvers. However, women demonstrated significantly improved cerebral autoregulation in the middle and anterior cerebral arteries, suggesting women were able to maintain cerebral blood flow during changes in blood pressure more efficiently than men.

Effects of menstrual cycle phase on associations between the error-related negativity and checking symptoms in women

The menstrual cycle is known to impact mood and cognitive function and has been shown to lead to variability in symptoms of obsessive-compulsive disorders and anxiety. Using a within-subject design, the present study examined ovarian hormones, the error-related negativity (ERN), and self-reported checking symptoms in both the mid-follicular and mid-luteal phases of the menstrual cycle. ERN amplitude and checking symptom severity did not vary between the follicular and luteal phases. However, a more negative ERN was associated with greater checking symptoms in the luteal phase of the menstrual cycle, even when controlling for ERN amplitude in the follicular phase. Moreover, changes in checking symptoms between phases were associated with phase-related changes in the ERN. Finally, a significant mediation model was found such that the ERN measured in the luteal phase mediated the association between progesterone in the luteal phase and checking symptoms in the luteal phase. Collectively, the present findings suggest that levels of progesterone in the luteal phase could impact checking symptoms by modulating response monitoring and sensitivity to errors, and that fluctuation in the ERN between menstrual cycle phases may play an important role in the expression of anxious and obsessive-compulsive symptoms.

The aroma of arousal: Effects of menstrual cycle phase and women’s sexual arousal state on men’s responsiveness to women’s body odor

Humans can detect aspects of identity, reproductive status, and emotional state from body odor. Women have shown a distinctive neural response to male sexually-aroused (vs. resting) sweat. The present study examined olfactory sexual arousal contagion in men. Axial sweat was collected from naturally cycling women when they were sexually aroused and when they were resting, during both their follicular and their luteal phase. Men were exposed to both aroused and resting sweat in a state of low-level sexual arousal. Participants smelling follicular phase sweat reported greater subjective sexual arousal and an increased likelihood to self-disclose than men smelling luteal phase sweat. They also showed increased genital arousal but this effect was moderated by the arousal state of the women; genital responding was greater in men smelling sexually aroused (vs. resting) sweat for those exposed to luteal (but not those exposed to follicular) phase body odor. Being able to detect the scent of sexual arousal could enhance perceiver arousal and provide information on whether to approach someone for sexual interaction.

The effect of menstrual cycle phase on foot skin temperature during mild local cooling in young women.

Japanese women can experience a sensation of cold feet in daily life. It is possible that this sensation of coldness in feet may be associated with female hormones, but to date the effect of menstrual cycle phase on the skin temperature (Tsk) of the foot during local cooling is unknown. We therefore examined Tsk and partial cutaneous blood flow in the foot during the follicular (F) and luteal (L) phases of the menstrual cycle in women experiencing local cooling. Tsk was measured in thetoes andthe dorsum of the left foot using infrared thermography, while cutaneous blood flow was evaluated in the big toe of the left footusing laser Doppler flowmetry (LDF), both at 28°C. Mild local cooling (24.7°C) was then applied for 30min to the right foot. During cooling of the right foot, no significant differences in Tsk were observed between the F and L phases in either the toes of the left foot or the dorsum of the left foot of all subjects. However, cutaneous blood flow determined by LDF in the big toe of the left foot was greater in the F phase than in the L phase. These results suggest that the menstrual cycle phase did not affect Tsk in the foot, but it did affect cutaneous blood flow in the big toe during mild local cooling.

Effects of menstrual cycle phase on electrocortical response to reward and depressive symptoms in women

The menstrual cycle impacts mood and neural response to reward-phenomena that may be related to natural fluctuations in ovarian hormones. Using a within-subject design, the present study examined ovarian hormones (i.e., estradiol and progesterone) and ERPs in response to feedback indicating gains and losses in both the follicular and luteal phases of the menstrual cycle. We examined whether hormone levels and variation in neural response to reward and loss across menstrual cycle phases were associated with depressive symptoms. Participants high in depressive symptoms showed a reduced reward positivity (RewP) to monetary gains during the luteal phase of the menstrual cycle as compared to the follicular phase, while those low in depressive symptoms showed no change in the RewP to monetary gains between phases. Thus, increased fluctuation in the neural response to gains (but not losses) across menstrual cycle phases was associated with greater depression symptoms. Overall, findings indicate that hormonal fluctuations associated with the menstrual cycle may relate to depressive symptoms by altering reward sensitivity. Furthermore, fluctuation in the neural response to rewards over the menstrual cycle may play an important role in the expression of depressive symptoms.

Analysis of the Effect of Menstrual Cycle Phases on Aerobic-Anaerobic Capacity and Muscle Strength

The objective of this study is to examine the effect of menstrual cycle phases on aerobic-anaerobic capacity and muscle strength. 10 female kickboxing athletes with an average age of 21.40±2.01 years; average height of 169.60±6.14 cm; average weight of 63.90±5.76 kg and average training age of 7.41±2.10 participated in the study. On the first day, maximal strength (1RM), strength endurance, wingate anaerobic power and capacity test (WAnT) were conducted and aerobic measurements were taken the next day. The measurements were conducted in follicular phase on the days 2-3rd of menstrual bleeding, in mid-follicular phase on 8-9th days and in luteal phase on 22-23th days. The data were analyzed with Friedman repeated measurements variance analysis. According to the results of the study, it was found that kickboxing athletes’ aerobic-anaerobic capacity, 1RM, strength endurance and heart rate (HR) were not affected by follicular phase, mid-follicular phase and luteal phase (p&gt;0.005). As a conclusion, it can be said that menstrual cycle does not influence performance parameters such as muscle strength, muscle endurance and aerobic-anaerobic capacity.

Processing emotions: Effects of menstrual cycle phase and premenstrual symptoms on the startle reflex, facial EMG and heart rate

Emotional reactivity varies across the menstrual cycle although physiological findings are not entirely consistent. We assessed facial EMG and heart rate (HR) changes in healthy free cycling women (N = 45) with an emotional startle paradigm both during the early follicular and the late luteal phase, verified by repeated salivary 17β-estradiol, progesterone and testosterone assessments. Cycle phase impacted startle responses with larger magnitudes during the luteal phase. Notably, this effect was only present when premenstrual symptoms and sequence of lab sessions were included as co-variates. At rest, participants showed a tendency towards higher HR and reduced high frequency (HF) power during the luteal phase indicating reduced parasympathetic tone. HF power was also negatively associated with startle magnitudes. HR changes in response to emotional images differed between the two cycle phases. Initial HR deceleration was more marked during the follicular phase particularly when viewing negative pictures. However, cycle phase did not significantly impact corrugator and zygomaticus activity in response to emotional pictures. Among the three gonadal steroids, correlation patterns were most consistent for testosterone. During the follicular phase, testosterone was associated with zygomaticus activity while viewing neutral or positive pictures and with less pronounced HR deceleration in response to negative images. During the luteal phase, testosterone was negatively associated with fear potentiated startle. The findings underscore the importance of considering menstrual cycle phase when investigating physiological indicators of emotion. However, the modulating effect of premenstrual symptoms also emphasizes potential inter-individual differences.

Characterizing the appetite‐regulatory response throughout the menstrual cycle

BackgroundObesity rates are higher among females than males potentially due to increases in food intake during certain phases of the menstrual cycle. The female sex hormones, progesterone (P4) and estradiol (E2), fluctuate across the menstrual cycle and are known to influence both energy intake and energy expenditure. Physiologically, the control of energy intake is partially mediated by circulating gut‐derived peptides that either stimulate appetite (acylated ghrelin (AG)) or induce satiety (PYY3–36 and GLP‐1). However, it remains poorly understood how the fluctuations in E2 and P4 influence appetite throughout the menstrual cycle via interactions with gut‐derived peptides, and whether these fluctuations in sex hormones also influence metabolic rate and substrate oxidation.PurposeTo examine changes in appetite regulating hormones, appetite perceptions, metabolic rate, and substrate oxidation during the follicular (FP), ovulatory (OP), and luteal (LP) phases of the menstrual cycle. We hypothesized that the LP, with increased P4, would be associated with greater concentrations of AG, low GLP‐1 and PYY3–36, and greater perceived hunger. Conversely, during the OP, with high concentrations of E2, there would be lower AG but greater concentrations of GLP‐1 and PYY3–36 with concomitantly diminished perceived hunger.MethodsNine healthy young females (age: 22.3±4.5 y; BMI: 23.91±3.52 kg·m−2) were studied during the FP, OP, and LP phases. Venous blood samples were collected following a 12 h overnight fast, and at 30, 60, and 90 min following a standardized test meal (29 kJ·kg−1 bw) to test for E2, P4, AG, PYY3–36, and GLP‐1. Perceptions of appetite were measured immediately prior to each blood sample using visual analogue scales. Fasted gas exchange was measured via indirect calorimetry to assess resting metabolic rate and substrate oxidation.ResultsFasting plasma E2 and P4 concentrations confirmed proper timing of experimental sessions. Post‐prandially there were main effects of time for AG (P=0.039) and GLP‐1 (P&lt;0.001), but not PYY3–36. Menstrual phase had no effect on fasting or post‐prandial plasma concentrations of AG or GLP‐1 (P&gt;0.05), but the post‐prandial change in PYY3–36 was lower during the LP compared to the FP (P=0.026) and OP (P=0.007). P4 concentrations correlated strongly with fasting AG concentrations in the LP only (r=0.93, P=0.024), while E2 correlated strongly with fasting GLP‐1 in the LP only (r=0.90, P=0.036). Fullness and satisfaction both increased over time (P&lt;0.001) and were greater during the OP compared to the FP and LP (P&lt;0.05). There was no effect of menstrual cycle phase on resting metabolic rate (P=0.388), carbohydrate oxidation rate (P=0.603), or fat oxidation rate (P=0.534).ConclusionThese results confirm that fluctuations in female sex hormones are associated with distinct hormonal and perceptual responses to feeding throughout the menstrual cycle.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of different phases of menstrual cycle in heart rate variability of physically active women

The menstrual cycle is characterized by an intense hormonal activity, mainly driven by estrogen and progesterone. During the menses, those hormones are usually with reduced levels, but it gradually increases its levels until the follicular phases, thus reaching ovulation. The aim of this study was to evaluate the effect of menstrual cycle phases in heart rate variability of trained women. In this study 19 women had participated, reporting their physical activity status (very active according to the International Physical Activity Questionnaire) and menstrual cycle period. Spectral analysis of HRV was used to calculate low-frequency or LF (0.04–0.15 Hz) and high frequency or HF (0.15–0.4 Hz). Normalized LF and HF components of R–R variability were considered, respectively, as markers of cardiac sympathetic and parasympathetic modulation, and the ratio between them (LF/HF) was considered as an index of the autonomic modulation of the heart. For the determination of the follicular and luteal phases, the monitoring for 5 months was used to characterize the regularity in days the menstrual cycle. As expected, an increased sympathetic and decreased parasympathetic balance was found in the luteal phase when compared to the follicular phase, as shown by increased low-frequency (LF) domains and, decreased RMSSD and HF indexes (p < 0.05). In conclusion, trained women showed reduced heart rate variability during the luteal phase when compared to the follicular phase.

Substrate oxidation in female adults during endurance exercise throughout menstrual cycle phases: IronFEMME pilot study

The main aim of the study was to investigate the effect of menstrual cycle phases on substrate oxidation during steady state intensity exercise in adult females with regular menstrual cycle and on oral contraceptive (OC). Twenty-four healthy endurance and strength trained females, with regular menstrual cycle phases (n= 15; Age 35.6±4.2; height 163.9±5.9 cm; body mass 58.1±5.2 kg; VO2peak 50.3±3.6 ml·min-1·kg-1) or on oral contraceptives (n=9; Age 30.4±4.5; height 163.9±9.0 cm; body mass 58.1±6.7 kg; VO2peak 52.4±4.2 ml·min-1·kg-1) participated in the study. All participants performed a graded maximal exercise test to determine their peak oxygen consumption (VO2peak). Participants then exercised at the speed corresponding to 75% of VO2peak for 40 minutes on a treadmill in each menstrual cycle phase: regular menstrual cycle group (early follicular phase, mid-follicular phase and luteal phase) and OC group (hormonal phase and non-hormonal phase). There were no differences in the respiratory exchange ratio of each phase, in regular menstrual cycle phase group (mean±SEM): early-follicular phase 0.89±0.01, mid-follicular phase 0.87±0.01 and luteal phase 0.88±0.01 (p>0.05). There were also no differences in respiratory exchange ratio for the participants using oral contraceptive: hormonal phase 0.89±0.01 and non-hormonal phase 0.91±0.01 (p>0.05). However, we found that OC may influence fat oxidation (p=0.018) during the hormonal phase. Our preliminary results suggest that menstrual cycle and oral contraceptive do not influence substrate oxidation in females with regular menstrual cycle phases. Regarding the few disparities, more research is needed to understand how sexual hormones influence substrate oxidation in female.