The effects of short-term resistance training on endocrine function in men and women

This investigation examined hormonal adaptations to acute resistance exercise and determined whether training adaptations are observed within an 8-week period in untrained men and women. The protocol consisted of a 1-week pre-conditioning orientation phase followed by 8 weeks of heavy resistance training. Three lower-limb exercises for the quadriceps femoris muscle group (squat, leg press, knee extension) were performed twice a week (Monday and Friday) with every other Wednesday used for maximal dynamic 1 RM strength testing. Blood samples were obtained pre-exercise (Pre-Ex), immediately post-exercise (IP), and 5?min post-exercise (5-P) during the first week of training (T-1), after 6 weeks (T-2) and 8 weeks (T-3) of training to determine blood concentrations of whole-blood lactate (LAC), serum total testosterone (TT), sex-hormone binding globulin (SHBG), cortisol (CORT) and growth hormone (GH). Serum TT concentrations were significantly (P?≤?0.05) higher for men at all time points measured. Men did not demonstrate an increase due to exercise until T-2. An increase in pre-exercise concentrations of TT were observed both for men and women at T-2 and T-3. No differences were observed for CORT between men and women; increases in CORT above pre-exercise values were observed for men at all training phases and at T-2 and T-3 for women. A reduction in CORT concentrations at rest was observed both in men and women at T-3. Women demonstrated higher pre-exercise GH values than men at all training phases; no changes with training were observed for GH concentrations. Exercise-induced increases in GH above pre-exercise values were observed at all phases of training. Women demonstrated higher serum concentrations of SHBG at all time points. No exercise-induced increases were observed in men over the training period but women increased SHBG with exercise at T-3. SHBG concentrations in women were also significantly higher at T-2 and T-3 when compared to T-1 values. Increases in LAC concentrations due to exercise were observed both for men and women for all training phases but no significant differences were observed with training. These data illustrate that untrained individuals may exhibit early-phase endocrine adaptations during a resistance training program. These hormonal adaptations may influence and help to mediate other adaptations in the nervous system and muscle fibers, which have been shown to be very responsive in the early phase of strength adaptations with resistance training.     

Changes in peak expiratory flow and respiratory strength during the menstrual cycle

This study evaluated the spirometry and respiratory static pressures in 17 young women, twice a week for three successive ovulatory menstrual cycles to determine if such variables changed across the menstrual, follicular, periovulatory, early-to-mid luteal and late luteal phases. The factors phases of menstrual cycle and individual cycles had no significant effect on the spirometry variables except for peak expiratory flow (PEF) and respiratory static pressures. Significant weak positive correlations were found between the progesterone:estradiol ratio and PEF and between estrogen and tidal volume (r = 0.37), inspiratory time (r = 0.22), expiratory time (r = 0.19), maximal inspiratory pressure (r = 0.25) and maximal expiratory pressure (r = 0.20) and for progesterone and maximal inspiratory pressure (r = 0.32) during the early-to-mid luteal phase. Although most parameters of the spirometry results did not change during the menstrual cycle, the correlations observed between sexual hormones and respiratory control variables suggest a positive influence of sexual female hormones controlling the thoracic pump muscles in the luteal phase.     

The role of the menstrual cycle phase in pain perception before and after an isometric fatiguing contraction

The purpose of this study was to compare exercise-induced analgesia in young women after a fatiguing isometric contraction during different phases of the menstrual cycle. Twenty female subjects performed a submaximal (25% maximal voluntary contraction) isometric contraction until task failure during both the mid-follicular and mid-luteal phases of their menstrual cycle. Pain perception (i.e., pain threshold and pain ratings) was measured before and after the isometric fatiguing contraction. Other measures included mean arterial pressure, heart rate, and anxiety levels. Time to task failure of the fatiguing contraction was similar for the two phases of the menstrual cycle. Following the performance of the isometric contraction: (1) pain thresholds increased and pain ratings decreased; (2) anxiety levels increased; and (3) mean arterial pressure and heart rate increased. These changes were not dependent on the phase of the menstrual cycle. Thus, the menstrual cycle phase does not influence the magnitude of exercise-induced analgesia.     

Effects of sex, phase of the menstrual cycle and gonadal hormones on pain in healthy humans

Sex differences in pain have been noted; women typically report more pain than men. Gonadal hormones may influence pain reports, and, moreover, such hormones may help to explain sex differences and menstrual cycle differences in pain. This study measured venipuncture and intravenous catherization pain during the follicular and luteal phases of the menstrual cycle in regularly menstruating women. Pain was also assessed in a group of men. Pain ratings were higher in women than men. In women, pain ratings did not differ between the follicular and luteal phases. Estradiol and progesterone increased from follicular to luteal phases. Within-phase analyses revealed that pain ratings were positively correlated with estradiol and progesterone during the luteal phase. Moreover, increases in estradiol and progesterone across the menstrual cycle were positively correlated with increases in pain. These findings suggest that variations in gonadal hormones during the menstrual cycle influence the experience of pain in healthy women.     

The effect of severe eccentric exercise-induced muscle damage on plasma elastase, glutamine and zinc concentrations

The aim of this study was to determine if severe exercise-induced muscle damage alters the plasma concentrations of glutamine and zinc. Changes in plasma concentrations of glutamine, zinc and polymorphonuclear elastase (an index of phagocytic cell activation) were examined for up to 10 days following eccentric exercise of the knee extensors of one leg in eight untrained subjects. The exercise bout consisted of 20 repetitions of electrically stimulated eccentric muscle actions on an isokinetic dynamometer. Subjects experienced severe muscle soreness and large increases in plasma creatine kinase activity indicative of muscle fibre damage. Peak soreness occurred at 2 days post-exercise and peak creatine kinase activity [21714 (6416) U · l⁻¹, mean (SEM)] occurred at 3 days post-exercise (P < 0.01 compared with pre-exercise). Plasma elastase concentration was increased at 3 days post-exercise compared with pre-exercise (P < 0.05), and is presumably indicative of ongoing phagocytic leucocyte infiltration and activation in the damaged muscles. There were no significant changes in plasma zinc and glutamine concentrations in the days following eccentric exercise. We conclude that exercise-induced muscle damage does not produce changes in plasma glutamine or zinc concentrations despite evidence of phagocytic neutrophil activation. Accepted: 3 November 1997     

Effects of menstrual cycle, oral contraception, and training on exercise-induced changes in circulating DHEA-sulphate and testosterone in young women

The objective of this study was to ascertain the effects of menstrual cycle, oral contraception, and training status on the exercise-induced changes in circulating DHEA-sulphate and testosterone in young women. Twenty-eight healthy women were assigned to an untrained group (n = 16) or a trained group (n = 12) depending on their training background. The untrained group was composed of nine oral contraceptive users (OC+) and seven eumenorrheic women (OC−). The trained group was composed of OC+ subjects only. All the OC+ subjects were taking the same low-dose oral contraception. Three laboratory sessions were organised in a randomised order: a prolonged exercise test until exhaustion, a short-term exhaustive exercise test, and a control session. Blood specimens were collected before, during and after the exercise tests and at the same time of the day during the control session. Basal circulating testosterone was significantly lower in trained as compared to untrained subjects. In all subjects, the prolonged exhaustive exercise induced a significant increase in circulating DHEA-s and testosterone. The short-term exercise induced a significant increase in circulating DHEA-s in untrained eumenorrheic and in trained OC users only. Menstrual phases in OC− did not influence the responses. It was found that exhaustive physical exercise induced an increase in circulating DHEA-s and testosterone in young women. Oral contraception may limit short-term exercise-induced changes.     

Effects of the menstrual cycle on mood, neurocognitive and neuroendocrine function in healthy premenopausal women

BACKGROUND: Neurocognitive functioning may be impaired in the luteal phase of the menstrual cycle due to associated changes in hypothalamic-pituitary adrenal (HPA) axis function. This study examines the relationship between changes in neurocognition and HPA axis function in different phases of the menstrual cycle. METHOD: Fifteen female volunteers, free from psychiatric history and hormonal medication were tested twice, during mid-follicular and late-luteal phases in a randomized, crossover design. Mood, neurocognitive function, and basal cortisol and dehydroepiandrosterone (DHEA) were profiled. RESULTS: Relative to the follicular phase, verbal fluency was impaired in the luteal phase and reaction times speeded on a continuous performance task, without affecting overall accuracy. 'Hedonic' scores on the UWIST-MACL scale were decreased in the luteal phase. There was also evidence of changes in the function of the HPA axis, with 24 h urinary cortisol concentrations and salivary DHEA levels being significantly lower during the luteal phase. CONCLUSIONS: These data suggest that luteal phase HPA axis function is lower than in the follicular phase in premenopausal healthy women. This putative biological difference may be important for our understanding of the aetiopathogenesis of menstrually related mood change and neurocognitive disturbance.     

Mechanisms underlying hemodynamic and neuroendocrine stress reactivity at different phases of the menstrual cycle

This study examined the association of menstrual cycle phase with stress reactivity as well as the hormonal and neuroendocrine mechanisms contributing to cycle effects. Fifty‐seven women underwent a modified Trier Social Stress Test during the early follicular, late follicular, and luteal phases of the menstrual cycle. Greater increases in cardiac index (CI) and greater decreases in vascular resistance index (VRI) during speech were observed in the luteal phase relative to other phases, while greater increases in epinephrine (EPI) was observed during the late follicular and luteal phases compared to the early follicular phase. Luteal phase estradiol predicted luteal EPI reactivity but not CI or VRI reactivity, while luteal phase EPI reactivity predicted luteal phase CI and VRI reactivity. Thus, cycle‐related changes in EPI reactivity may be a stronger determinant of cycle effects on hemodynamic reactivity than sex hormones per se.     

Effects of human menstrual cycle on thermoregulatory vasodilation during exercise

Summary To investigate the effects of the menstrual cycle and of exercise intensity on the relationship between finger blood flow (FBF) and esophageal temperature (T_es), we studied four women, aged 20–32 years. Subjects exercised at 40% and 70% in the semi-supine posture at an ambient temperature of 20 C. Resting T_es was higher during the luteal phase than the follicular phase (P<0.01). There were no significant differences between the two phases in FBF, oxygen consumption, carbon dioxide production, heart rate or minute ventilation at rest and during exercise, respectively. Each regression line of the FBF-T_es relationship consists of two distinct segments of FBF change to T_es (slope 1 and 2). FBF increased at a threshold T_es for vasodilation ([T_{es 0}]) and the rate of FBF rise became greater at another T_es above this threshold ([T_{es 0}']). For both levels of exercise, [T_{es 0}] and [T_{es 0}'] were shifted upward during the luteal phase, but the slopes of the FBF-T_es relationship were almost the same in the two phases of the menstrual cycle. Increasing exercise intensity induced a significant decrease in slope 1 of the FBF-T_es relationship during the follicular (P<0.01) and the luteal phases (P<0.02), respectively. These results show that the set-point temperature may be shifted towards a higher level during the luteal phase of the menstrual cycle during exercise and that, as in males, the thermoregulatory vasodilator response is attenuated by increasing exercise-induced vasoconstrictor tone in proportion to exercise intensity during both phases of the menstrual cycle when heat storage is insufficient in women.Supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (grant no. 57770137)     

Effects of the menstrual cycle phase on the blood lactate responses to exercise

The effects of menstrual cycle phase on the blood lactate response to exercise were examined in eumenorrheic women (n=9). Exercise tests were performed at the mid-follicular and mid-luteal points in the menstrual cycle (confirmed by basal body temperature records and hormone levels). Blood lactates were measured at rest and during the recovery from exercise. Resting lactates were not different between the exercise tests; however, recovery lactates were significantly (p < 0.05) lower in the luteal compared to the follicular phase. The mechanism for these differences is unclear, but may be related to an estrogen mediated increased lipid metabolism inducing a concurrent reduction in carbohydrate metabolism. The present findings question the use of blood lactate monitoring as a suitable technique to measure exercise intensity in eumenorrheic women.     

Exercise-induced oxidative stress and muscle performance in healthy women: role of vitamin E supplementation and endogenous oestradiol

The purpose of this study was to investigate the individual and combined antioxidant effects of menstrual cycle phase-related alterations in blood serum oestradiol concentrations and of dietary vitamin E supplementation on exercise-induced oxidative stress and muscle performance. A group of 18 sedentary women, aged 19–35 years, were given supplements of 300 mg α-tocopherol (n=10) or placebo (n=8) daily during the course of two menstrual cycles. The subjects exercised the knee isokinetically to exhaustion after cycling submaximally at 50% maximal oxygen uptake during the menstrual and preovulatory phases of their menstrual cycles. Blood samples were taken before and after the exercise, to evaluate haematocrit, plasma lactic acid and malondialdehyde concentrations, erythrocyte antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and apolipoprotein B containing lipoprotein (non-high density lipoprotein, HDL, fraction) oxidation. Serum vitamin E, follicle stimulating hormone, luteinizing hormone and oestradiol concentrations were measured in pre-exercise blood samples. Neither vitamin E supplementation nor oestradiol concentrations influenced SOD and GPx activities or the susceptibility of the non-HDL fraction to oxidation while at rest. Plasma malondialdehyde concentration was unaffected by exercise, however significant reductions in erythrocyte SOD and GPx activities and increased susceptibility of the non-HDL fraction to oxidation were noted after exercise. Exercise-induced changes were reduced when oestradiol concentration was high in the preovulatory phase, independent of the serum vitamin E concentrations. In addition, both pre- (r=0.58, P < 0.05) and post-exercise (r=0.73, P < 0.001) GPx activities in placebo administered subjects were positively correlated with oestradiol concentrations. In conclusion, these findings suggest a better protective role of oestradiol against oxidative injury, compared to vitamin E. Exhausting muscle performance was, however, not influenced by vitamin E supplementation and/or cycle-phase related changes in oestradiol concentrations. Accepted: 18 September 2000     

Influence of menstrual cycle phase on pulmonary function in asthmatic athletes

The main aim of this study was to investigate whether there is a relationship between menstrual cycle phase and exercise-induced bronchoconstriction (EIB) in female athletes with mild atopic asthma. Seven eumenorrheic subjects with regular 28-day menstrual cycles were exercised to volitional exhaustion on day 5 [mid-follicular (FOL)] and day 21 [mid-luteal (LUT)] of their menstrual cycle. Pulmonary function tests were conducted pre- and post-exercise. The maximal percentage decline in post-exercise forced expiratory volume in 1 s (FEV₁) and forced expiratory flow from 25 to 75% of forced vital capacity (FEF_25–75%) was significantly greater (P<0.05) on day 21 (mid-LUT phase) (−17.35±2.32 and −26.28±6.04%, respectively), when salivary progesterone concentration was highest, compared to day 5 (mid-FOL phase) (−12.81±3.35 and −17.23±8.20%, respectively), when salivary progesterone concentration was lowest. The deterioration in the severity of EIB during the mid-LUT phase was accompanied by worsening asthma symptoms and increased bronchodilator use. There was a negative correlation between the percent change in pre- to post-exercise FEV₁ and salivary progesterone concentration. However, no such correlation was found between salivary estradiol and the percentage change in pre- to post-exercise FEV₁. This study has shown for the first time that menstrual cycle phase is an important determinant of the severity of EIB in female athletes with mild atopic asthma. Female asthmatic athletes may need to adjust their training and competition schedules to their menstrual cycle and to consider the potential negative effects of the LUT phase of the menstrual cycle on exercise performance.     

Cardiovascular functioning during the menstrual cycle.

Variations in cardiovascular functioning during the 'normal' menstrual cycle have been little researched. Resting-blood pressures, resting-heart rate, rate-pressure product (RPP) and a derived index of fitness (Schneider Index) were monitored throughout natural, hormonally defined menstrual cycles. Volunteers were 26 women (20-48 years) who had regular (25-35 days) cycles. Their blood pressures and heart rate (at rest and according to Schneider's protocol) were measured at the same time daily (Monday-Friday) for 5 weeks. Daily, early morning-urine samples were assayed for sex hormones enabling accurate definition of cycle phase for each woman. Resting systolic-blood pressure was significantly higher in the ovulatory phase (P < 0.05) than in the follicular or luteal phases, but resting-diastolic pressures did not differ significantly between phases. Resting-heart rate was significantly higher in both ovulatory (P < 0.01) and luteal (P < 0.01) phases than in the menstrual and follicular phases. The Schneider Index was higher during the follicular phase than during the ovulatory (P < 0.005) or luteal (P < 0.01) phases, the RPP was higher during the ovulatory phase than during the bleeding (P < 0.05) and follicular (P < 0.005) phases. These findings provide a pattern of menstrual cycle-related variation in cardiovascular functioning that can be related to established actions of the ovarian steroids.     

Endocrinology: Vasopressin and atrial natriuretic hormone response to hypertonic saline during the follicular and luteal phases of the menstrual cycle

We studied the hormonal responses to hypertonic saline duringthe follicular (days 2–9) and luteal (days 21–28)phases of the menstrual cycle in nine healthy young women, aged19–25 years. On both study days, each woman was infusedwith 5% hypertonic saline for 1 h at the rate of 0.1 ml/kg/min.Serum progesterone and oestradiol concentrations confirmed thereported stage of the menstrual cycle. No difference in weightor haematocrit was observed between the two stages of the studyfor each woman. Baseline blood pressure, serum sodium, plasmaosmolality, plasma vasopressin and thirst levels were almostidentical for both stages, and changed to the same degree duringinfusion of hypertonic saline. Baseline atrial natriuretic hormoneconcentrations were higher during the follicular phase and becamesignificantly higher than during the luteal phase followinginfusion of hypertonic saline. We concluded that the intravascularvolume during the luteal phase may be effectively decreasedin comparison to the follicular phase.     

The effects of exercise intensity on thermoregulatory responses to exercise in women

We investigated the influence of altering exercise intensity (150, 300, and 450 kpm/min) on the resetting of the core temperature threshold for the onset of the sweating rate (M(sw)) and the alteration of sweating sensitivity during the menstrual cycle in women. Five women underwent cycling exercise for 30 min in both the luteal and follicular phases under controlled neutral environmental conditions (T: 25 degrees C, RH: 55%). A significantly higher rectal temperature (T(re)) was seen in the luteal phase at all exercise intensities, and the same time course of the T(re) response with a constant difference of approximately 0.2 degrees C was shown between the follicular phase and the luteal phase. The T(re) threshold for M(sw) was also apparently shifted rightward a constant value of 0.2 degrees C from the follicular phase to the luteal phase, independent of the alteration of exercise intensity. The slope of the M(sw)-T(re) relationship in the follicular phase did not differ from that in the luteal phase. These results indicate that (1) a rightward shift in the T(re) threshold from the follicular phase to the luteal phase can be observed independent of any alteration of the exercise intensity; and (2) the sensitivity of M(sw) is also not physiologically influenced by exercise intensity. Thus, alterative thermoregulation during the menstrual cycle was fundamentally unaffected by the change of exercise intensity.     

Strength training effects on urinary steroid profile across the menstrual cycle in healthy women

Some studies suggest that performing strength training may cause alterations on the hypothalamic pituitary axis, resulting in steroid hormone variations. Intense training has been associated to slow the concentrations of estrogens and progesterone in women. The main purpose of this study was to evaluate the effects of strength training on the urinary steroid concentrations across the menstrual cycle phases. Twenty healthy women, regularly menstruating and not using pharmacologic contraceptives, performed a strength training during 8 weeks. Participants worked out 3 sets × 10 repetitions, with 2 min recovery time between sets, at 70–75 % of one maximum strength repetition. Urine samples were taken in three different phases of the menstrual cycle (menstrual, follicular and luteal) and they were collected both before and after training. Testosterone, DHEA, cortisol, cortisone, estradiol and progesterone concentrations were determined by gas chromatography-mass spectrometry. The results showed a significant decline after training in the urinary excretion of estradiol, during the menstrual and follicular phase, and progesterone, during the menstrual and luteal phase. No significant difference was observed for other steroid hormones. These data demonstrated that strength training can play an important role in the estrogen and progesterone metabolism in women, decreasing their levels across the menstrual cycle.     

Variations in carotid arterial compliance during the menstrual cycle in young women

The effect of menstrual cycle phase on arterial elasticity is controversial. In 10 healthy women (20.6+/-1.5 years old, mean+/-s.d.), we investigated the variations in central and peripheral arterial elasticity, blood pressure (carotid and brachial), carotid intima-media thickness (IMT), and serum oestradiol and progesterone concentrations at five points in the menstrual cycle (menstrual, M; follicular, F; ovulatory, O; early luteal, EL; and late luteal, LL). Carotid arterial compliance (simultaneous ultrasound and applanation tonometry) varied cyclically, with significant increases from the values seen in M (0.164+/-0.036 mm2 mmHg-1) and F (0.171+/-0.029 mm2 mmHg-1) to that seen in the O phase (0.184+/-0.029 mm2 mmHg-1). Sharp declines were observed in the EL (0.150+/-0.033 mm2 mmHg-1) and LL phases (0.147+/-0.026 mm2 mmHg-1; F=8.51, P<0.05). Pulse wave velocity in the leg (i.e. peripheral arterial stiffness) did not exhibit any significant changes. Fluctuations in carotid arterial elasticity correlated with the balance between oestradiol and progesterone concentrations. No significant changes were found in carotid and brachial blood pressures, carotid artery lumen diameter, or IMT throughout the menstrual cycle. These data provide evidence that the elastic properties of central, but not peripheral, arteries fluctuate significantly with the phases of the menstrual cycle.     

Lower olfactory threshold during the ovulatory phase of the menstrual cycle

We investigated whether olfactory detection threshold is correlated with phase of the menstrual cycle. Three hundred and thirty-two women 13-49 years old were tested once during either the follicular, ovulatory, luteal or menstrual phase, and 15 women 20-43 years old were tested at each of these phases across one complete cycle. In three non-cycling control groups subjects were each tested once; 83 post-menopausal women 47-86 years old, 60 pre-pubertal girls 5-12 years old, and 183 men 17-30 years old. Odor detection thresholds were determined using sniff bottles containing -log9.5 to -log6.0 concentrations of amyl acetate presented in ascending order. Thresholds differed significantly across the cycle and were lowest during the ovulatory and highest during the menstrual phase. Thresholds for all control groups were higher than for the cycling women during the ovulatory phase. The results confirm that olfactory threshold is related to phase of the menstrual cycle and thus possibly to hormonal state.     

The relationship between exercise-induced oxidative stress and the menstrual cycle

The purpose of this study was to investigate the relationship between exercise-induced oxidative stress and the menstrual cycle in healthy sedentary woman. Eighteen women with regular menstrual cycles participated in this research. The subjects monitored their basal body temperature (BBT) and carried out a urinary ovulation test (twice) for 2 months prior to the study to determine their menstrual cycle. The subjects performed bicycle ergometer exercise (for 30 min at 60% O_2max) in each phase (menses, follicular and luteal phases) of the menstrual cycle. Serum estradiol and progesterone concentrations were determined from blood that was collected at rest. Serum thiobarbituric acid reactive substances (TBARS), total superoxide dismutase (T-SOD) and extracellular superoxide dismutase (EC-SOD) were determined as markers of oxidative stress in blood samples collected at rest and after exercise. TBARS was significantly lower after exercise [2.4 (0.5) nmol/ml] in the follicular phase, and T-SOD was significantly lower after exercise [3.2 (1.2) U/ml] in the luteal phase. EC-SOD did not show a significant change after exercise during each phase of the menstrual cycle. Furthermore, there was a negative correlation between estradiol and T-SOD (r=–0.46, P<0.05) and between estradiol and EC-SOD (r=–0.55, P<0.05) during the menses. All data are presented as the mean value and its standard deviation.The results of this study suggest that when the estradiol level is high in a menstrual cycle, free radicals produced as a consequence of exercise may be easily eliminated by sedentary women with normal menstrual cycles.     

Fluctuations in carotid arterial distensibility during the menstrual cycle do not influence cardiovagal baroreflex sensitivity

Aim: Fluctuations in autonomic nervous functions throughout the menstrual cycle and the underlying mechanism concerning them are not well known. This study was designed to test the hypothesis that fluctuations in cardiovagal baroreflex sensitivity (BRS) throughout the menstrual cycles of young women are due to fluctuations in carotid arterial distensibility. Methods: In eight eumenorrhoeic healthy young women (18–24 years), we determined the variations in the carotid arterial distensibility coefficient (DC; via simultaneous ultrasonography and applanation tonometry), cardiovagal BRS (phase IV of the Valsalva manoeuvre and the sequence method; up‐ or down‐sequence spontaneous BRS), and serum oestradiol and progesterone concentrations at five points in the menstrual cycle (menstrual = M, follicular = F, ovulatory = O, early luteal = EL, and late luteal = LL). Results: Serum oestradiol and progesterone levels were consistent with the predicted cycle phases. Carotid arterial DC fluctuated cyclically, increasing significantly from the M (52.4 ± 4.9 × 10^?3 kPa^?1, mean ± SE) and F (52.7 ± 4.4) phases to the O (57.6 ± 4.4) phase and declining sharply in the EL (46.0 ± 4.0) and LL (45.1 ± 3.0) phases (F = 6.37, P < 0.05). Contrary to our prediction, however, cardiovagal BRS by the Valsalva manoeuvre (P = 0.73) or sequence method (up‐sequence spontaneous BRS; P = 0.84: down‐sequence spontaneous BRS; P = 0.67) did not change significantly during the menstrual cycle. Conclusion: The results suggest that, although carotid arterial distensibility fluctuates with the changes in ovarian hormone levels that occur during the menstrual cycle, the fluctuations in carotid arterial distensibility do not influence cardiovagal BRS.