Evaluation of sensitivity,motor and pain thresholds across the menstrual cycle through medium-frequency transcutaneous electrical nerve stimulation

OBJECTIVES:

The aim of this study was to identify variations in nervous thresholds in different phases of the menstrual cycle in eumenorrheic women and users of oral contraceptives.

METHOD:

An observational study was performed including 56 volunteers, consisting of 30 eumenorrheic women who were non-users of oral contraceptives and 26 users of oral contraceptives. An electrical stimulator was employed to assess their nervous thresholds, with pulses applied at a fixed frequency of 2,500 Hz, modulated at 50 Hz, with phase variances of 20 μs, 50 μs and 100 μs. Sensitivity, motor and pain thresholds were evaluated during five menstrual cycle phases: phase 1 - menstrual, phase 2 - follicular, phase 3 - ovulatory, phase 4 - luteal and phase 5 - premenstrual.

RESULTS:

The results indicated low sensitivity thresholds of 100 μs for non-users of oral contraceptives and 50 μs for oral contraceptive users in phase 5. Low motor thresholds of 20 μs, 50 μs and 100 μs were observed for non-users of oral contraceptives in phase 5, while that of oral contraceptive users was 100 μs. Finally, a low pain threshold of 100 μs was observed in phase 5, but only in the oral contraceptive group.

CONCLUSION:

Nervous thresholds vary systematically across the phases of the menstrual cycle, with or without the use of oral contraceptives. These variations should be taken into account during research performed in women.     

Sex-related differences in thermoregulatory responses while wearing protective clothing

This study examined the thermoregulatory responses of men (group M) and women (group F) to uncompensable heat stress. In total, 13?M [mean (SD) age 31.8 (4.7) years, mass 82.7 (12.5)?kg, height?1.79?(0.06)?m, surface area to mass ratio 2.46?(0.18)?m²?·?kg^?1?·?10^?2, Dubois surface area 2.01 (0.16)?m², %body fatness 14.6 (3.9)%, V˙O_2peak 49.0?(4.8)?ml?·?kg^?1?·?min^?1] and 17 F [23.2 (4.2) years, 62.4 (7.7)?kg, 1.65 (0.07)?m, 2.71 (0.14)?m²?·?kg^?1?·?10^?2, 1.68 (0.13)?m², 20.2 (4.8)%, 43.2 (6.6)?ml?·?kg^?1?·?min^?1, respectively] performed light intermittent exercise (repeated intervals of 15?min of walking at 4.0?km?·?h^?1 followed by 15?min of seated rest) in the heat (40°C, 30% relative humidity) while wearing nuclear, biological, and chemical protective clothing (0.29?m²?·°C · W^?1 or 1.88 clo, Woodcock vapour permeability coefficient 0.33?i _m). Group F consisted of eight non-users and nine users of oral contraceptives tested during the early follicular phase of their menstrual cycle. Heart rates were higher for F throughout the session reaching 166.7 (15.9) beats?·?min^?1 at 105?min (n?=?13) compared with 145.1 (14.4)?beats?·?min^?1 for M. Sweat rates and evaporation rates from the clothing were lower and average skin temperature ( ) was higher for F. The increase in rectal temperature (T _re) was significantly faster for the F, increasing 1.52 (0.29)°C after 105?min compared with an increase of 1.37?(0.29)°C for M. Tolerance times were significantly longer for M [142.9?(24.5)?min] than for F [119.3?(17.3)?min]. Partitional calorimetric estimates of heat storage (S) revealed that although the rate of S was similar between genders [42.1?(6.6) and 46.1?(9.7) W?·?m^?2 for F and M, respectively], S expressed per unit of total mass was significantly lower for F [7.76?(1.44)?kJ?·?kg^?1] compared with M [9.45?(1.26) kJ?·?kg^?1]. When subjects were matched for body fatness (n?=?8?F and 8?M), tolerance times [124.5?(14.7) and 140.3?(27.4)?min for F and M, respectively] and S [8.67?(1.44) and 9.39?(1.05)?kJ?·?kg^?1 for F and M, respectively] were not different between the genders. It was concluded that females are at a thermoregulatory disadvantage compared with males when wearing protective clothing and exercising in a hot environment. This disadvantage can be attributed to the lower specific heat of adipose versus non-adipose tissue and a higher percentage body fatness.     

The menstrual cycle from a bio-behavioral approach: A comparison of oral contraceptive and non-contraceptive users

The purpose of the present study was to clarify the effects of the menstrual cycle on: (1) accuracy and simple reaction time in a problem-solving situation; (2) academic performance; (3) identify corresponding cyclic changes in a set of psychophysiological measures during rest/test conditions; and (4) to compare oral contraceptive with non-oral contraceptive users. Eight volunteer females, 4 normally cyclic and 4 oral contraceptive users, reported once weekly throughout two menstrual cycles during which changes in blood pressure, heart rate, skin temperature, finger pulse amplitude, and verbal reaction time were monitored. Differences in verbal reaction time were found between oral contraceptive users and non-users over phases of the cycle, the users being significantly slower during menstrual and premenstrual phases. It was also observed that all subjects reacted slower in the menstrual and ovulatory phases during cycle one, although no differences were found during cycle two. Skin temperature changes between groups occured during the postovulatory phase of cycle two, the control group having shown a much greater increase than oral contraceptive users. These results indicated a suppressive influence of oral contraceptives which appeared to affect cognitive rather than motor responses, and that these effects were residual when no pills were taken menstrually and premenstrually. Also indicated was the finding that although a 28-day cycle of menstrual events exists, periodicity of these events may be reflected in a much larger cycle non-currently defined.     

Effect of menstrual phase on the acetate correction factor used in metabolic tracer studies.

The acetate correction factor is used to account for retention of carbon label in exchange reactions of the tricarboxylic acid cycle in studies estimating free fatty acid oxidation with carbon-labeled tracers. Previous evidence indicates that substrate utilisation and metabolic rate vary across the menstrual cycle, which may alter the correction factor. We therefore derived the acetate correction factor for each of three menstrual phases (early follicular [EF], late follicular [LF], and midluteal [ML] phase) from the fractional recovery of 13CO2 from a constant infusion of sodium-[1-13C] acetate during 90 min of submaximal exercise (60% VO2-max) in sedentary eumenorrhoeic women. There was no difference in the correction factor between the EF and LF or the LF and ML phases, but the correction factor derived in the ML phase was significantly lower than in the EF phase (p < 0.05). Neither energy expenditure nor whole body substrate utilisation during exercise varied significantly between menstrual phases and therefore cannot explain the observed difference in the correction factor. The lower correction factor in the ML phase, compared to the EF phase, would result in only a small increase of -6% in the calculated plasma free fatty acid oxidation rate.     

Influence of hydration status and fluid replacement on heat tolerance while wearing NBC protective clothing

The purpose of the present study was to investigate the influence of hypohydration and fluid replacement on tolerance to an uncompensable heat stress. Eight healthy young males completed a matrix of six trials in an environmental chamber, set at 40°C and 30% relative humidity, while wearing nuclear, biological, and chemical protective clothing. Subjects performed either light (3.5 km · h⁻¹, 0% grade, no wind) or heavy (4.8 km · h⁻¹, 4% grade, no wind) treadmill exercise combined with three hydration states [euhydration with fluid replacement (EU/F), euhydration without fluid replacement (EU/NF), and hypohydration with fluid replacement (H/F)]. Hypohydration of 2.2% body mass was achieved by exercise and fluid restriction on the day preceding the trials. No differences in the endpoint mean skin temperature (Tˉ_sk), sweat rate, or rectal temperature (T _re) were observed among the hydration conditions for either work rate. During light exercise, the change in T _re (ΔT _re) was significantly higher with H/F than EU/F after 40 min, and heart rate was greater after 25 min. The heart rate was greater during EU/NF than during EU/F after 60 min. Tolerance times were significantly greater for EU/F than for either EU/NF or H/F. With heavy exercise, no differences in ΔT _re were observed across hydration conditions. Compared to EU/F, heart rates were higher after 10 and 30 min for H/F and EU/NF, respectively. Tolerance times were significantly less during H/F than with either of the EU conditions. Stroke volume was significantly decreased in H/F trials compared to EU/F trials for both light and heavy work rates, but no differences in cardiac output were observed. It was concluded that even minor levels of hypohydration significantly impaired exercise tolerance in a severely uncompensable heat stress environment at both light and heavy exercise intensities. Accepted: 17 June 1997     

A prospective study evidencing rhinomanometric and olfactometric outcomes in women taking oral contraceptives.

BACKGROUND: The aim of this prospective study was to evaluate the changes in olfactory sensitivity of oral contraceptive (pill) users. METHODS: Sixty women underwent rhinomanometric and olfactometric determinations during the follicular, periovular and luteal phases of the menstrual cycle, and at day 7, 14 and 21 of contraceptive intake. Thirty-one women used 30 microg ethinyl oestradiol plus 75 microg gestodene and 29 women used 20 microg ethinyl oestradiol plus 150 microg desogestrel. RESULTS: Rhinomanometry showed higher but not statistically significant values during the periovular phase than in the follicular and luteal phases. Olfactometry showed a higher sensitivity during the follicular and periovular phases than during the luteal phase of the menstrual cycle. The rhinomanometric surveys in pill users were statistically different from those of the luteal phase (P < 0.02) and the follicular and periovular phases (P < 0.001). The olfactometric thresholds during the period of contraceptive use were statistically different from those of the follicular phase for a few odorous substances, and from those of the periovular phase for each odorous substance, but similar to those of the luteal phase (P = NS). CONCLUSIONS: Unlike the rhinomanometric airflow and trans-nasal pressure, the olfactory threshold to odours seems to depend on the variations of the ovarian steroids during the menstrual cycle and on the iatrogenic effects of oral contraceptives.     

Cycling time trial performance during different phases of the menstrual cycle

Submaximal exercise performance has not previously been assessed in the late follicular phase of the menstrual cycle, which is associated with a pre-ovulatory surge in oestrogen. Therefore, we compared cycling time trial performance during the early follicular (EF), late follicular (LF) and mid-luteal (ML) phase of the menstrual cycle in trained and untrained eumenorrhoeic women who cycled 30 and 15 km, respectively, in a non-fasted state. The women completed the three cycling time trials on a conventional racing bicycle mounted on an air-braked ergometer. We required resting oestrogen to increase by at least twofold above EF phase values in both the LF and ML phases and this resulted in a number of exclusions reducing the sample size of each group. No significant difference was noted in the finishing time between the different menstrual phases in trained (n=5) or untrained (n=8) group, albeit limited by sample size. However, analysis of the combined trained and untrained group data (n=13) revealed a trend for a faster finishing time (P=0.027) in the LF phase compared to the EF phase as 73% of the subjects showed improvements with an average of 5.2±2.9% (or 2.1±1.1 min) in the LF phase (for =0.05 requires P<0.017). Combined group analysis yielded no difference between performance in the EF and ML phase or between the LF and ML phase. Thus, further research is encouraged to confirm the tendency for a faster time trial in the LF phase, which coincides with the pre-ovulatory surge in oestrogen.     

Responses of menstrual women,amenorrheal women,and men to exercise in a hot,dry environment

Summary Rectal (T_re) and mean skin temperatures, heart rate (fc) and sweat rate (M_sw) during exercise in a hot, dry environment were compared among four menstrual women (both before and after ovulation), four amenorrheal women and four men, all with similar aerobic capacities. Progesterone and estrogen were compared in a pair of monozygotic twins (one menstrual and one amenorrheal) who participated in the study. Before acclimation, subjects were given a heat-stress test (HST) consisting of treadmill walking at 25%–30% max in a hot, dry environment (T_db/T_wb=48/25 C) until T_re reached 39 C or fc reached 160 beat·min^–1. Subjects were then acclimated to the dry heat with conventional acclimation procedures. After acclimation, subjects were given a HST which continued for 3 h. Before acclimation T_re and fc increased more rapidly in the women, which resulted in significantly shorter HST times for the women as compared with the men. Following acclimation all subjects maintained similar T_re, fc, and sweat rates. There were no differences between the exercise/heat-stress responses of the preovulatory menstrual women, postovulatory menstrual women, and amenorrheal women. Although the estrogen concentrations were normal in the menstrual twin, her progesterone concentrations were significantly depressed. Both hormones were depressed in the amenorrheal twin. Following acclimation thermoregulatory function in dry heat did not differ between the sexes when fitness level was similar. Neither were there any differences in thermoregulation between the pre- and postovulatory phases of the menstrual cycle or between the menstrual and amenorrheal women.     

Effect of the menstrual cycle on performance of intermittent,high-intensity shuttle running in a hot environment

The present study examined the impact of the menstrual cycle and oral contraceptive use on performance of high-intensity intermittent running in the heat [31.0 (0.2)°C; 23.1 (0.9)% relative humidity]. Seven normally menstruating women (NM) and eight oral contraceptive (OC) users participated in the study. Two trials were undertaken near the predicted mid-point of the follicular (FT) and luteal (LT) phases of the menstrual cycle and the equivalent days for the OC users. Basal serum progesterone concentrations were higher during the LT for the NM group [FT: 2.42 (0.28) nmol l^–1 vs LT: 25.96 (11.28) nmol l^–1; P<0.05], but were not different for the OC users [days 1–14: 2.79 (0.38) nmol l^–1 vs days 15–28: 2.61 (0.32) nmol l^–1]. There were no differences in distance run between menstrual cycle phases or between the normally menstruating and OC groups [NM FT: 6257 (1401) m vs LT: 5861 (1035) m]. However, the OC ran further in days 15–28 compared to days 1–14 [OC 1–14: 5481 (612) m vs 15–28: 6615 (893) m, P<0.05]. For the NM, rectal temperature, perceived exertion, estimated SR, serum growth hormone, plasma lactate, ammonia and glucose did not differ between phases of the menstrual cycle. For the OC group, heart rate, perceived exertion, sweat rate, plasma lactate and ammonia did not differ between days 1–14 of OC use and days 15–28. However, rectal temperature was higher (P<0.05) and growth hormone tended to be higher (P=0.05) during days 15–28, while plasma glucose was lower (P<0.05). These results demonstrate that for unacclimatised games players the performance of intermittent, high-intensity shuttle running in the heat is unaffected by menstrual cycle phase but is influenced by OC use. Electronic Publication     

Melatonin has no effect on tolerance to uncompensable heat stress in man

This study examined whether a 5 mg dose of melatonin induced a lower rectal temperature (T _re) response at rest in both a cool and hot environment while wearing normal military combat clothing, and then examined the influence of this response on tolerance to exercise in the heat while wearing protective clothing. Nine men performed four randomly ordered trials involving 2 h of rest at ambient temperatures of either 23 °C or 40 °C followed by exercise at an ambient temperature of 40 °C. The double-blind ingestion of placebo or melatonin occurred after 30 min of rest. The mean T _re during rest at 23 °C had decreased significantly from 36.8 (SD 0.1) °C to 36.7 (SD 0.2) °C at 90 min following the ingestion of the drug, whereas values during the placebo trial did not change. The lower T _re response during the melatonin trial remained during the first 50 min of exercise in the heat while wearing the protective clothing. Since the final mean T _re at the end of exercise also was significantly reduced for the melatonin [39.0 (SD 0.4) °C] compared with the placebo [mean 39.1 (SD 0.3) °C] trial, tolerance times approximated 95 min in both conditions. During rest at 40 °C, melatonin did not affect the mean T _re response which increased significantly during the last 90 min from 36.9 (SD 0.1) °C to 37.3 (SD 0.1) °C. This increase in T _re during the rest period prior to donning the protective clothing decreased tolerance time approximately 30 min compared with the trials that had involved rest at 23 °C. Total heat storage summated over the rest and exercise periods was not different among the trials at 15 kJ · kg⁻¹. It was concluded that the small decrease in T _re following the ingestion of 5 mg of melatonin at rest in a cool environment had no influence on subsequent tolerance during uncompensable heat stress. Accepted: 26 June 2000     

Influence of short-term aerobic training and hydration status on tolerance during uncompensable heat stress

The purpose of the present study was to determine the separate and combined effects of a short-term aerobic training program and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40°C, 30% relative humidity). Males of moderate fitness [<50?ml?·?kg^?1?·?min^?1 maximal O₂ consumption (V˙O_{2 max} )] were tested while euhydrated or hypohydrated by ≈2% of body weight through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after either a 2-week program of daily aerobic training (1?h treadmill exercise at 65% V˙O_{2 max} for 12 days; n?=?8) or a control period (n?=?7), which had no effect on any measured variable. The training increased V˙O_{2 max} by 6.5%, while heart rate (f _c) and the rectal temperature (T _re) rise decreased during exercise in a thermoneutral environment. In the heat, training resulted in a decreased skin temperature and increased sweat rate, but did not affect f _c, T _re or tolerance time (TT). In both training and control groups, hypohydration significantly increased T _re and f _c and decreased the TT. It was concluded that the short-term aerobic training program had no benefit on exercise-heat tolerance in this uncompensable heat stress environment.     

Thermoregulation during exercise in women who are taking oral contraceptives

Thermoregulation during exercise was studied in seven women who were taking oral contraceptive pills for 3 weeks of each month. The subjects were studied once in the 3rd week of taking the pill (P) and once during the following week when they took no pill (N). Rectal temperature (T _re), heart rate (f _c) and evaporative water loss (EWL, ventilated capsule technique) were measured while they walked on a treadmill for 60 min at 4.8 km?·?h^?1 at a 10% gradient. Ambient temperature was 22?°C. A venous blood sample was drawn 30 min before each experiment for measurement of hematocrit (packed cell volume, PCV), plasma osmolality (Osm _pl), and plasma levels of the endogenous pyrogens interleukin-1β (IL-1β) and interleukin-6 (IL-6). Resting T _re was 0.31?°C higher in P than in N (P?T _re remained higher in P throughout the entire exercise period (P?T _re for the onset of EWL was 0.32?°C higher in P than in N (P?f _c was 6.5 beats?·?min^?1 higher in P than in N (P?Osm _pl, IL-1β or IL-6 between P and N. It was concluded that the administration of synthetic progestins in oral contraceptives causes an upward shift in the threshold for heat loss responses, resulting in higher body core temperatures both at rest and during exercise. There was no evidence that these alterations in thermoregulation were mediated by changes in body fluid balance or in plasma levels of IL-1β or IL-6.     

Latina contraceptive decision-making and use: The importance of provider communication and shared decision-making for patient-centered care

BackgroundPoor patient-provider communication, among other reasons, is a notable barrier to contraceptive decision-making among Latinas. Patient-centered approaches to contraceptive counseling that optimize communication align with shared decision-making (SDM) –which is associated with satisfaction and continued contraceptive use among various populations.ObjectiveTo examine associations of patient-provider communication and importance of SDM tenets with consistent contraceptive use among a population of Latinas.Patient involvementFormative work for this study included prior qualitative and quantitative research with Latinas who expressed the importance of patient-provider communication during contraceptive counseling and therefore were instrumental in problem definition.MethodsCross-sectional surveys were administered to Latinas ages 15–29 years. Patient-provider communication, patient-reported importance of specific SDM tenets, and consistent contraception use were measured and analyzed for associations.Results103 Latinas (mean age = 21.4) participated. 33% of participants<21 years were using contraception consistently vs. 67% for those ≥ 21 (p = 0.003). Among participants ≥ 21, consistent users reported higher communication scores compared to inconsistent users and non-users (p = 0.042). For participants< 21, consistent users were more likely than inconsistent users and non-users to report that 2 SDM tenets (discussion of contraceptive preferences and avoidance of race/ethnic-based judgement) are important (p = 0.052, 0.028, respectively).DiscussionPatient-provider communication was especially important for Latinas ≥ 21 while using an SDM approach during counseling was highly valued by those<21. Patient-centered approaches to contraceptive counseling provide opportunities to optimize healthcare delivery for this vulnerable population.Practical valueResults from this research demonstrate that patient-centered communication is highly valued by Latina study participants and is an important consideration in their contraceptive counseling. Clinicians should consider employing techniques such as SDM as they seek to provide patient-centered care during contraceptive counseling for this patient population.     

Effects of menstrual cycle phase and oral contraceptive use on intermittent exercise

Five women using low-dose, monophasic oral contraceptive (OC) agents (OC group) and ten normally menstruating women (Non-OC group) performed a treadmill protocol to determine the effect of OCs and the menstrual cycle (MC) on intermittent exercise performance and some commonly used metabolic markers. The Non-OC group were tested once in the mid-follicular phase (MFP) and once in the late luteal phase (LLP) of the MC, while the OC group performed their first test within 1 week of taking the OC (T1) and their second test 1 week later (T2). Despite performance time being the same in both groups [mean (SD), Non-OC group: 77.7 (14.9)?s versus OC group: 77.7 (21.1)s], plasma ammonia concentration ([NH₃]_pl) was higher in the Non-OC group when compared to the OC group throughout recovery (P?T _au) between groups. Within the Non-OC group T _au increased with exercise in both phases (P?T _au was higher in the LLP at rest [36.1 (0.3)°C) and 1?min post-exercise [37.1 (0.6)°C), when compared to the MFP [35.8 (0.3) and 36.9 (0.7)°C, rest and 1?min post-exercise respectively, P?3]_pl (143.0 (26.2) Umol/l] when compared to T2 [BLa, 9.6 (0.9); [NH₃], 119.4 (48.1), P<0.05]. These results suggest that: (1) exercise performance does not vary between the MFP and the LLP of the MC, nor does it appear to be affected by the number of days using the OC, and (2) an altered metabolism occurs both between groups (Non-OC versus OC) and within the OC group.     

Health correlates and mode of administration of hormones—Are there any differences between parenteral and oral estrogen preparations?

Objectives

To investigate use-associated differences between parental and oral hormone therapy (HT) users in reference to HT non-users regarding self-rated general health status, quality of life, health service utilization, and selected chronic diseases.

Methods

All cases of last-week medicine use were recorded among 2248 women aged 40–79 who participated in the German Health Interview and Examination Survey 1997–1999. 89 current parenteral HT users and 322 oral HT users were identified. Health correlates were compared between the two groups in reference to HT non-users.

Results

Oral HT users had a poorer current health status as well as an impaired health status compared to the year before, were less satisfied with their health and life in general, and showed a lower quality of life regarding ‘body pain’ and ‘vitality’ in comparison with hormone non-users (all p < .05). Parenteral HT users showed no significant difference compared with HT non-users and oral HT users, respectively, in these health correlates except for a less satisfaction with health found in comparison with HT non-users (p = .002). Prevalences of cerebral-cardiovascular diseases were not different among women using parenteral or oral HT use. Parenteral HT users visited the offices of general practitioner and gynecologists more frequently than oral HT users as well as hormone non-users (all p < .05).

Conclusions

Oral HT use is associated with a negative assessment for health well-being whereas parenteral HT use shows largely a neutral effect. Further designated studies could clarify whether the mode of hormone administration consistently affects health-related quality of life and whether the mode of hormone treatment influences the choice of outpatient facilities for surveillance of therapy.     

Lack of genotoxicity induced by endogenous and synthetic female sex hormones in peripheral blood cells detected by alkaline comet assay

The etiology of hormone-induced cancers has been considered to be a combination of genotoxic and epigenetic events. Currently, the Comet assay is widely used for detecting genotoxicity because it is relatively simple, sensitive, and capable of detecting various kinds of DNA damage. The present study evaluates the genotoxic potential of endogenous and synthetic sex hormones, as detected by the Comet assay. Blood cells were obtained from 12 nonsmoking and 12 smoking women with regular menstrual cycles and from 12 nonsmoking women taking low-dose oral contraceptives (OC). Peripheral blood samples were collected at three phases of the menstrual cycle (early follicular, mean follicular, and luteal phases), or at three different moments of oral contraceptive intake. Three blood samples were also collected from 12 healthy nonsmoking men, at the same time as oral contraceptive users. Results showed no significant difference in the level of DNA damage among the three moments of the menstrual cycle either in nonsmoking and smoking women, or between them. No significant difference in DNA damage was also observed among oral contraceptive users, nonusers, and men. Together, these data indicate lack of genotoxicity induced by the physiological level of the female sex hormones and OC as assessed by the alkaline Comet assay. In conclusion, normal fluctuation in endogenous sex hormones and use of low-doses of oral contraceptive should not interfere with Comet assay data when this technique is used for human biomonitoring.     

Significant changes in VLDL-Triacylglycerol and glucose tolerance in obese subjects following ten days of training

We characterized the effect of ten days of training on lipid metabolism in 6 [age 37.2 (2.3) years] sedentary, obese [BMI 34.4?(3.0)?kg?·?m^?2] males with normal glucose tolerance. An oral glucose tolerance test was performed prior to and at the end of the 10?d of training period. The duration of each daily exercise session was 40?min at an intensity equivalent to ?75% of the age predicted maximum heart rate. Blood measurements were performed after an overnight fast, before and at the end of the 10?d period. Plasma triacylglycerol was significantly (p??1). Very low density lipoprotein-triacylglycerol was also significantly?(p??1). No significant changes in high density lipoprotein-cholesterol were observed as a result of training. Following training fasting plasma glucose and fasting plasma insulin were significantly reduced [Glucose: 5.9 (0.2)?mmol?·?l^?1 vs.?5.3 (0.22)?mmol?·?l^?1 (p??1 vs. 200.9 (30.1) ρ?·?mol?·?l^?1, p?=?0.05]. The total area under the glucose curve during the OGTT decreased significantly (p?相似文献   

Heart rate variability across the menstrual cycle in young women taking oral contraceptives

Previous studies have shown that resting heart rate variability (HRV) is modified by different phases of the menstrual cycle in nonusers of oral contraceptive pills (OCP); however, the effect of OCP on autonomic control of the heart remains unclear. The purpose of this study was to investigate HRV during the low hormone (LH—not taking OCP) and during the high hormone (HH—active OCP use) phases of the menstrual cycle in young women. Seventeen healthy women (19–31 years) taking OCP for at least 6 consecutive months were enrolled in this study. Plasma estradiol and progesterone were verified at each visit. HRV was assessed by using one‐lead electrocardiography in time and frequency domains, in which participants rested in the supine position for a 20‐min period with a breathing rate of 15 cycles/min. In addition, resting heart rate, and systolic and diastolic blood pressure were obtained. Both plasma estradiol (LH: 19.8 ± 4.2 pg/mL vs. HH: 12.4 ± 1.5 pg/mL; p > .05) and progesterone (LH: 0.247 ± 0.58 ng/mL vs. HH: 0.371 ± 0.08 ng/mL; p > .05) (mean ± SE) levels were similar in both phases. No significant difference was obtained for any component of HRV, heart rate, or blood pressure between the LH and HH phases (p > .05). These results provide preliminary evidence that use of OCP does not affect HRV during the menstrual cycle in healthy women.     

Oral contraceptive use and histopathology of cancerous breasts in young women. Members of the U.K. National Case-Control Study Group.

A retrospective histopathological study of 300 women under 36 years of age was carried out to determine whether breast cancers occurring in oral contraceptive users showed any differences in pathological features compared with non-users. The patients belong to an age group in which an increased risk of cancer development has been reported following oral contraceptive usage. The incidence of non-neoplastic conditions in the residual breast was also studied in the two groups. There was little difference between breast cancers arising in pill users and non-users but in the residual non-neoplastic breast a decreased incidence of cysts and blunt duct adenosis was found in current users of the contraceptive pill. In contrast, lactational foci were found only in the breasts of pill users. The incidence of intraductal hyperplasia was not significantly different in the two groups.     

Testosterone levels in relation to oral contraceptive use and the androgen receptor CAG and GGC length polymorphisms in healthy young women

BACKGROUND: The combined effect from the androgen receptor (AR) CAG and GGC length polymorphisms on testosterone levels has not been studied in young women. METHODS: Testosterone levels were measured in blood drawn on both menstrual cycle days 5-10 and 18-23 in 258 healthy women, aged < or =40 years, from high-risk breast cancer families. CAG and GGC length polymorphisms were analysed by PCR and fragment analyses. All women completed a questionnaire including information on oral contraceptive (OC) use and reproductive factors. RESULTS: OC users had lower median testosterone levels than non-users during cycle days 5-10 and 18-23 (P < or = 0.005 for both). The BRCA mutation status was associated neither with testosterone levels nor with CAG or GGC length polymorphism. The CAG length polymorphism was not associated with testosterone levels. The cumulative number of long GGC alleles (> or =17 repeats) was significantly associated with lower testosterone levels in OC users during cycle days 5-10 (P(trend) =0.014), but not during cycle days 18-23 or in non-users. The interaction between the GGC length polymorphism and OC status was highly significant during cycle days 5-10 (P = 0.002) and near-significant during days 18-23 (P = 0.07). Incident breast cancer was more common in women with two short GGC alleles (log-rank P = 0.003). CONCLUSION: The GGC repeat length was the only significant genetic factor modifying the testosterone levels in current OC users from high-risk families. Homozygosity for the short GGC allele may be linked to the increased risk of early-onset breast cancer after OC exposure in high-risk women.