Dose-Response Relationships between Diet Quality and Mortality among Frail and Non-Frail Older Adults: A Population-Based Kyoto-Kameoka Prospective Cohort Study.

OBJECTIVES: Although better diet quality is inversely associated with mortality risk, the association between diet quality and mortality remains unclear in frail and non-frail older adults. Thus, we aimed to examine this association in older Japanese adults. DESIGN: A prospective cohort study. SETTING AND PARTICIPANTS: We used the data of 8,051 Japanese older adults aged ≥65 years in the Kyoto-Kameoka study. MESUREMENTS: Dietary intake was estimated using a validated food frequency questionnaire. Diet quality was evaluated by calculating the adherence scores to the Japanese Food Guide Spinning Top (range, 0 [worst] to 80 [best]), which were stratified into quartiles. Frailty status was assessed using the validated self-administered Kihon Checklist (KCL) and the Fried phenotype (FP) model. Survival data were collected between February 15, 2012 and November 30, 2016. Statistical analysis was performed using the multivariate Cox proportional hazard analysis and the spline model. RESULTS: During the median 4.75-year follow-up (36,552 person-years), we recorded 661 deaths. After adjusting for confounders, compared with the bottom adherence score quartile, the top quartile was associated with lower hazard ratio (HR) of mortality in frailty (HR, 0.73; 95% confidence interval [CI], 0.54-1.00) and non-frailty, as defined by the KCL (HR, 0.72; 95% CI, 0.52-1.01). In the spline model, regardless of frailty status defined by the KCL and FP model, adherence score showed a strongly dose-dependent inverse association with mortality up to approximately 55 points; however, no significant differences were observed thereafter. This association was similar to the results obtained in individuals with physical, cognitive, and depression as domains of KCL in the spline model. CONCLUSIONS: Our findings demonstrate an L-shaped association between diet quality and mortality in both frail and non-frail individuals. This study may provide important knowledge for improving poor diet quality in older individuals with frailty or domains of frailty.

Heritability estimates of endurance-related phenotypes: A systematic review and meta-analysis.

The aim of this study was to clarify heritability estimates for endurance-related phenotypes and the underlying factors affecting these estimates. A systematic literature search was conducted for studies reporting heritability estimates of endurance-related phenotypes using the PubMed database (up to 30 September 2016). Studies that estimated the heritability of maximal oxygen uptake (V˙O2max), submaximal endurance phenotypes, and endurance performance were selected. The weighted mean heritability for endurance-related phenotypes was calculated using a random-effects model. A total of 15 studies were selected via a systematic review. Meta-analysis revealed that the weighted means of the heritability of V˙O2max absolute values and those adjusted for body weight and for fat-free mass were 0.68 (95% CI: 0.59-0.77), 0.56 (95% CI: 0.47-0.65), and 0.44 (95% CI: 0.13-0.75), respectively. There was a significant difference in the weighted means of the heritability of V˙O2max across these different adjustment methods (P < .05). Moreover, there was evidence of statistical heterogeneity in the heritability estimates among studies. Meta-regression analysis revealed that sex could partially explain the heterogeneity in the V˙O2max heritability estimates adjusted by body weight. For submaximal endurance phenotypes and endurance performance, the weighted mean heritabilities were 0.49 (95% CI: 0.33-0.65) and 0.53 (95% CI: 0.27-0.78), respectively. There was statistically significant heterogeneity in the heritability estimates reported among the studies, and we could not identify the specific factors explaining the heterogeneity. Although existing studies indicate that genetic factors account for 44%-68% of the variability in endurance-related phenotypes, further studies are necessary to clarify these values.

The Association Between MCT1 T1470A Polymorphism and Power-Oriented Athletic Performance.

The purpose of this study was to investigate the effects of the MCT1 T1470A polymorphism (rs1049434) on power-oriented performance and lactate concentration during or after cycling sprints in Japanese wrestlers. Participants (199 wrestlers and 649 controls) were genotyped for the MCT1 T1470A genotype (rs1049434) using the TaqMan® Assay. All wrestlers were international (n=77) or national (n=122) level athletes. Among them, 46 wrestlers performed 2 anaerobic performance tests, a 30-s Wingate Anaerobic test (WAnT) and a series of 10 maximal effort 10-s sprints on a cycle ergometer. Blood lactate levels were measured before, during, and after the tests. In the A-allele recessive model (AA vs. TA+TT), the frequency of the AA genotype was significantly higher in all wrestlers than in controls (p=0.037). Wrestlers with AA genotype had lower blood lactate concentrations than those with TA+TT genotype at 10 min after the WAnT and following the 5th and the final set of repeated cycling sprints (p<0.05). The AA genotype of the MCT1 T1470A polymorphism is over-represented in wrestlers compared with controls and is associated with lower blood lactate concentrations after 30-s WAnT and during intermittent sprint tests in Japanese wrestlers.

Heritability estimates of muscle strength-related phenotypes: A systematic review and meta-analysis.

The purpose of this study was to clarify the heritability estimates of human muscle strength-related phenotypes (H2 -msp). A systematic literature search was conducted using PubMed (through August 22, 2016). Studies reporting the H2 -msp for healthy subjects in a sedentary state were included. Random-effects models were used to calculate the weighted mean heritability estimates. Moreover, subgroup analyses were performed based on phenotypic categories (eg, grip strength, isotonic strength, jumping ability). Sensitivity analyses were also conducted to investigate potential sources of heterogeneity of H2 -msp, which included age and sex. Twenty-four articles including 58 measurements were included in the meta-analysis. The weighted mean H2 -msp for all 58 measurements was 0.52 (95% confidence intervals [CI]: 0.48-0.56), with high heterogeneity (I2 =91.0%, P<.001). Subgroup analysis showed that the heritability of isometric grip strength, other isometric strength, isotonic strength, isokinetic strength, jumping ability, and other power measurements was 0.56 (95% CI: 0.46-0.67), 0.49 (0.47-0.52), 0.49 (0.32-0.67), 0.49 (0.37-0.61), 0.55 (0.45-0.65), and 0.51 (0.31-0.70), respectively. The H2 -msp decreased with age (P<.05). In conclusion, our results indicate that the influence of genetic and environmental factors on muscle strength-related phenotypes is comparable. Moreover, the role of environmental factors increased with age. These findings may contribute toward an understanding of muscle strength-related phenotypes.

Interference Effect between ϕ and Λ(1520) Production Channels in the γp→K

The ϕ-Λ(1520) interference effect in the γp→K^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between ϕ and Λ(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrt[s]=2.1 GeV bump structure in forward differential cross sections for ϕ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.

CNTFR Genotype and Sprint/power Performance: Case-control Association and Functional Studies.

The aim of this study was to investigate whether rs41274853 in the 3'-untranslated region of the ciliary neurotrophic factor receptor gene (CNTFR) is associated with elite sprint/power athletic status and assess its functional significance. A total of 211 Japanese sprint/power track and field athletes (62 international, 72 national, and 77 regional athletes) and 814 Japanese controls were genotyped at rs41274853. Luciferase reporter assay was conducted to investigate whether this C-to-T polymorphism affects binding of microRNA miR-675-5p to this region. The TT genotype was significantly more frequent among international sprint/power athletes (19.4%) than in the controls after Bonferroni correction (7.9%, P=0.036, OR=2.81 [95% CI: 1.43-5.55]). Furthermore, in non-athletic young/middle-aged men (n=132), TT genotype carriers exhibited significantly greater leg extension power (26.6±5.4 vs. 24.0±5.4 W/kg BW, P=0.019) and vertical jump performance (50.1±6.9 vs. 47.9±7.5 cm, P=0.047) than the CC+CT genotype carriers. Reporter assays revealed that the miR-675-5p binds to this polymorphic region within the CNTFR mRNA, irrespective of the rs41274853 allele present. Although the functional significance of the rs41274853 polymorphism remains unclear, the CNTFR is one of the candidate genes contributing to sprint/power performance.

Weight change after 20 years of age and the incidence of dyslipidemia: a cohort study of Japanese male workers.

BACKGROUND: While heavier weight is known to increase the incidence of dyslipidemia, limited data are available on the relationship between weight gain and its development. METHODS: A total of 2647 males were categorized into the following four groups according to the difference between their self-reported weight at 20 years of age and their measured weight in 1994-95: a loss of ≥5% (decrease), loss of <5% or gain of <5% (no change), gain of ≥5 to <15% (increase) and gain of ≥15% (sizable increase). They were followed up until their 2002-03 health examination. Using the 'no change' group as reference, the multivariable-adjusted odds ratio (adjusted for age, body mass index at 20 years of age, physical activity, smoking and alcohol intake) and 95% confidence interval (95% CI) for the incidence of dyslipidemia were determined using logistic regression models. RESULTS: A total of 1342 participants developed dyslipidemia during the follow-up period. The 'increase' and 'sizable increase' groups had odds ratios for the incidence of dyslipidemia of 1.97 (95% CI, 1.59-2.45) and 2.68 (2.15-3.34), respectively, demonstrating that there was a significant dose-response association between weight gain since 20 years of age and the incidence of dyslipidemia (P < 0.001 for trend). CONCLUSION: These results suggest that dyslipidemia could be prevented by avoiding weight gain in adulthood.

Identification of the 12q15 amplicon within the homogeneously staining regions in the embryonal rhabdomyosarcoma cell line RMS-YM.

Gene amplification represents one of the molecular mechanisms of oncogene overexpression in many types of tumors. Homogeneously staining regions (HSRs) are cytogenetic hallmarks of gene amplification. Rhabdomyosarcoma is the most common malignant soft-tissue tumor in children. RMS-YM is an embryonal rhabdomyosarcoma cell line that possesses 3 HSRs. This cytogenetic finding suggests the presence of gene amplifications associated with tumor development or progression in RMS-YM. Here, using fluorescence in situ hybridization, we detected high amplification of the MDM2 gene in the HSRs of RMS-YM. We also refined the region of the amplicon and identified that the FRS2 gene and others are amplified in RMS-YM. MDM2 and FRS2 play important roles as a regulator of p53 and a mediator of FGF signaling, respectively, and thus are potential molecular targets for therapy in many different tumors. RMS-YM may be useful for studies of the molecular pathways of tumorigenesis and tumor progression in rhabdomyosarcoma and for in vitro evaluation of newly developed therapeutic agents that target MDM2 or FRS2.

PAX3-NCOA2 fusion gene has a dual role in promoting the proliferation and inhibiting the myogenic differentiation of rhabdomyosarcoma cells.

We analyzed a complex chromosomal translocation in a case of embryonal rhabdomyosarcoma (RMS) and showed that it generates the fusion gene PAX3 (paired box 3)-NCOA2 (nuclear receptor coactivator 2). To understand the role of this translocation in RMS tumorigenesis, we established two types of stable mouse myoblast C2C12 cell lines expressing PAX3-NCOA2 and PAX3-FOXO1A (forkhead box O1A), respectively. Compared with control cells, PAX3-NCOA2 cells grew faster, were more motile, were less anchorage dependent, progressed more quickly through the G1/S phase of cell cycle and showed greater transcriptional activation of the PAX3 consensus-binding site. However, PAX3-NCOA2 cells proliferated more slowly and differentiated more weakly than did PAX3-FOXO1A cells. Both PAX3-NCOA2 cells and PAX3-FOXO1A cells formed tumors in nude mice, although the PAX3-NCOA2-induced tumors grew more slowly. Our results may explain why NCOA2 rearrangement is mainly found in embryonal rhabdomyosarcoma, which has a better prognosis than alveolar rhabdomyosarcoma, which expresses the PAX3-FOXO1A fusion gene. These results indicate that the PAX3-NCOA2 fusion gene has a dual role in the tumorigenesis of RMS: promotion of the proliferation and inhibition of the myogenic differentiation of RMS cells.

ACTN3 R577X genotype is associated with sprinting in elite Japanese athletes.

The ACTN3 R577X genotype has been found to associate with sprint/power phenotypes in all elite athlete cohorts investigated. This association has not been extensively studied in elite Asian athletes. The present study was undertaken to investigate the association between the ACTN3 R577X genotype and elite Japanese track and field athlete status. 299 elite Japanese track and field athletes (134 sprint/power athletes; 165 endurance/middle-power athletes) and 649 Japanese controls were genotyped for the ACTN3 R577X polymorphism. All athletes were of national or international level. Sprint/power athletes showed a higher frequency of RR + RX genotype than controls (111/134 [82.8%] vs. 478/649 [73.7%], P = 0.025 under the R-dominant model), while there was no significant difference between endurance/middle-power athletes and controls (126/165 [76.4%] vs. 478/649 [73.7%], P = 0.48 under the R-dominant model). Sprinters with the RR + RX genotype had significantly faster personal best times for the 100 m than those with XX genotype (10.42 ± 0.05 s vs. 10.64 ± 0.09 s, P = 0.042); no such association was found in the 400 m sprinters (47.02 ± 0.36 s vs. 47.56 ± 0.99 s, P = 0.62). ACTN3 R577X genotype is associated with sprint/power performance in elite Japanese track and field athletes, especially short sprint performance.

Adverse effects of coexistence of sarcopenia and metabolic syndrome in Japanese women.

BACKGROUND/OBJECTIVES: Little information is available regarding the interactions of sarcopenia and metabolic syndrome (MetS) in the risks of these age-associated diseases in women. The present cross-sectional study was performed to investigate whether the coexistence of sarcopenia and MetS further increases the risks of lifestyle-related diseases in Japanese women. SUBJECTS/METHODS: Healthy Japanese women (n=533) aged 30-84 participated in this study. MetS was defined as higher body mass index, fasting plasma glucose, systolic or diastolic blood pressure and blood lipid abnormalities. Appendicular muscle mass and bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry. The criterion of low muscle mass and strength defined median skeletal muscle index (appendicular muscle mass/height², kg/m²) and handgrip strength. RESULTS: Two-way ANCOVA with adjustment for age, body fat percentage and whole-body lean tissue mass indicated that sarcopenia and MetS interacted to produce a significant effect on HbA1c, systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity in Japanese women. The systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity were significantly higher in women with coexisting sarcopenia and MetS than in healthy controls or in those with sarcopenia or MetS alone. The HbA1c in the coexisting sarcopenia and MetS group was higher than in healthy controls and sarcopenia subjects. CONCLUSIONS: The coexistence of sarcopenia and MetS further increases the risks of cardiovascular diseases, such as type 2 diabetes mellitus, hypertension, arterial stiffness and hyperlipidemia even adjustment of age and body composition in adult Japanese women.

Mitochondrial macrohaplogroup associated with muscle power in healthy adults.

The present study was undertaken to examine the effect of mitochondrial haplogroups on aerobic and anaerobic performance phenotypes such as maximum oxygen consumption, muscle power, and muscle mass. We recruited 474 healthy Japanese individuals and measured their physical performance phenotypes such as peak oxygen uptake, muscle power, and muscle mass. The genotypes for 186 polymorphisms in the mitochondrial DNA were determined, and the haplotypes were classified into 2 macrohaplogroups (i. e., N and M) and 12 haplogroups (i. e., F, B, A, N9a, N9b, M7a, M7b, G1, G2, D4a, D4b, and D5). When we compared the 2 major Japanese macrohaplogroups, leg extension power (P=0.0395), leg extension power based on body weight (P=0.0343), and vertical jump performance (P=0.0485) were significantly higher in subjects with mitochondrial macrohaplogroup N than in those with macrohaplogroup M. However, peak oxygen uptake was similar between the 2 groups. When we analyzed the 12 haplogroups, all of the measured parameters were similar among them. In conclusion, mitochondrial macrohaplogroup N may be one of the determinant factors of anaerobic physical performance phenotype such as muscle power.

A cross-sectional study of sarcopenia in Japanese men and women: reference values and association with cardiovascular risk factors.

In this study of Japanese men and women, we determine reference values for sarcopenia and test the hypothesis that sarcopenia is associated with risk factors for cardiovascular disease, independent of waist circumference. A total of 1,488 Japanese men and women aged 18-85 years participated in this study. Appendicular muscle mass (AMM) was measured by dual-energy X-ray absorptiometry. Reference values for classes 1 and 2 sarcopenia (skeletal muscle index: AMM/height2, kg m-2) in each sex were defined as values one and two standard deviations below the sex-specific means of reference values obtained in this study from young adults aged 18-40 years. The reference values for class 1 and class 2 sarcopenia were 7.77 and 6.87 kg m-2 in men and 6.12 and 5.46 kg m-2 in women. In subjects both with class 1 and class 2 sarcopenia, body mass index and % body fat were significantly lower than in normal subjects. Despite whole-blood glycohaemoglobin A1c in men with class 1 sarcopenia was significantly higher than in normal subjects, and brachial-ankle pulse wave velocity in women both with class 1 and class 2 sarcopenia were significantly higher than in normal subjects, using one-way ANCOVA with adjustment for the covariate of waist circumference. Although sarcopenia is associated with thin body mass, it is associated with more glycation of serum proteins in men and with greater arterial stiffness in women, independent of waist circumference.

Age and cardiorespiratory fitness are associated with arterial stiffening and left ventricular remodelling.

Arterial stiffening, hypertension and left ventricular (LV) remodelling are associated with increased risk of cardiovascular disease. Cardiorespiratory fitness is associated with cardiovascular function and reduced risk of cardiovascular disease. This cross-sectional study was carried out to determine the relationships between cardiorespiratory fitness, arterial stiffness, blood pressure (BP) and LV remodelling in women. On the basis of peak oxygen uptake, a total of 159 premenopausal (young) and postmenopausal (older) women were categorized into either low (unfit) or high (fit) cardiorespiratory fitness groups. The arterial stiffness and LV remodelling were measured by brachial-ankle pulse wave velocity (baPWV) and carotid augmentation index (AI) and LV relative wall thickness (RWT). Two-way analysis of variance indicated a significant interaction between age and cardiorespiratory fitness in baPWV, carotid AI, BP and RWT. In the older group, arterial stiffness (baPWV; 1401+/-231 vs 1250+/-125 cm s(-1), P<0.01, AI; 32.9+/-9.9 vs 24.8+/-10.1%, P<0.01), systolic blood pressure (SBP) (130+/-22 vs 117+/-15 mm Hg, P<0.01) and RWT (0.47+/-0.08 vs 0.42+/-0.04, P<0.05) in fit women were lower than in unfit women. In older women, RWT was significantly related to baPWV (r=0.46, P<0.01), carotid AI (r=0.29, P<0.05), SBP (r=0.57, P<0.01) \[V(2peak) (r=-0.32, P<0.05). In young women, they were not significant correlations, except for a weak correlation between RWT and SBP (r=0.21, P<0.05). These results suggest that higher cardiorespiratory fitness is associated with lower arterial stiffness, BP and RWT in older women.

Near-threshold photoproduction of Lambda(1520) from protons and deuterons.

Photoproduction of Lambda(1520) with liquid hydrogen and deuterium targets was examined at photon energies below 2.4 GeV in the SPring-8 LEPS experiment. For the first time, the differential cross sections were measured at low energies and with a deuterium target. A large asymmetry of the production cross sections from protons and neutrons was observed at backward K+/0 angles. This suggests the importance of the contact term, which coexists with t-channel K exchange under gauge invariance. This interpretation was compatible with the differential cross sections, decay asymmetry, and photon beam asymmetry measured in the production from protons at forward K+ angles.

Resting energy expenditure can be assessed by dual-energy X-ray absorptiometry in women regardless of age and fitness.

OBJECTIVE: To evaluate the possibility that measurement of the magnitude and distribution of fundamental somatic heat-producing units using dual-energy X-ray absorptiometry (DXA) can be used to estimate resting energy expenditure (REE) in both young and elderly women with different aerobic fitness levels. SUBJECTS AND METHODS: Peak oxygen uptake (VO(2) peak) and REE(m) were directly measured in 116 young (age: 22.3+/-2.1 years) and 72 elderly (63.3+/-6.4 years) women. The subjects were divided into four groups according to categories of age and VO(2) peak; young: high fitness (YH, n=58); low fitness (YL, n=58); elderly: high fitness (EH, n=37) and low fitness (EL, n=35). Using DXA, systemic and regional body compositions were measured, and REE(e) was estimated from the sum of tissue organ weights multiplied by corresponding metabolic rate. RESULTS: Although there were remarkable differences in systemic and regional body compositions, no significant differences were observed between REE(m) and REE(e) in the four groups. REE(e) significantly correlated with REE(m) in elderly as well as young women; the slopes and intercepts of the two regression lines were statistically not different between the elderly and young groups (elderly: y=0.60x + 472, r=0.667; young: y=0.78x + 250, r=0.798; P<0.001, respectively). A Bland-Altman analysis did not indicate bias in calculation of REE for all the subjects. CONCLUSION: These results suggest that REE can be estimated from tissue organ components in women regardless of age and aerobic fitness.

Muscle mass and bone mineral indices: does the normalized bone mineral content differ with age?

OBJECTIVE: To investigate the relationships between regional skeletal muscle mass (SM mass) and bone mineral indices and to examine whether bone mineral content (BMC) normalized to SM mass shows a similar decrease with age in young through old age. SUBJECTS/METHODS: One hundred and thirty-eight young and postmenopausal women aged 20-76 years participated in this study and were divided into three groups: 61 young women, 49 middle-aged postmenopausal women and 28 older postmenopausal women. Muscle thickness (MTH) was determined by ultrasound, and regional SM mass (arm, trunk and leg) was estimated based on nine sites of MTH. Whole-body and regional lean soft tissue mass (LSTM), bone mineral density (BMD) and BMC (whole body, arms, legs and lumbar spine) were measured using dual-energy X-ray absorptiometry. RESULTS: Ultrasound spectroscopy indicated that SM mass is significantly correlated with site-matched regional bone mineral indices and these relationships correspond to LSTM. The BMC and BMD in older women were significantly lower than those in middle-aged women. When BMC was normalized to site-matched regional SM mass, BMC normalized to SM mass in arm and trunk region were significantly different with age; however, whole-body and leg BMC normalized to SM mass showed no significant difference between middle-aged and older postmenopausal women. CONCLUSIONS: The age-related differences in BMC were found to be independent of the ageing of SM mass in the arm and trunk region. However, differences in BMC measures of the leg and whole body were found to correspond to age-related decline of SM mass in postmenopausal women.

A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials.

OBJECTIVE: It has been suggested that exercise has preferential effects on visceral fat reduction. However, the dose-response effect remains unclear because of limited evidence from individual studies. The purpose of this study was to systematically review the current literature to establish whether reduction of visceral fat by aerobic exercise has a dose-response relationship. METHODS: A database search was performed (PubMed, 1966-2006) with appropriate keywords to identify studies exploring the effects of aerobic exercise as a weight loss intervention on visceral fat reduction. Visceral fat reduction was expressed as the percentage of visceral fat change per week (%DeltaVF/w). The energy expenditure by aerobic exercise was expressed as Sigma (metabolic equivalents x h per week (METs x h/w)). RESULTS: Nine randomized control trials and seven non-randomized control trials were selected. In most of the studies, the subjects performed aerobic exercise generating 10 METs x h/w or more. Among all the selected groups (582 subjects), visceral fat decreased significantly (P<0.05) in 17 groups during the intervention, but not in the other 4 groups. There was no significant relationship between METs x h/w from aerobic exercise and %DeltaVF/w in all the selected groups. However, when subjects with metabolic-related disorders were not included (425 subjects), METs x h/w from aerobic exercise had a significant relationship with %DeltaVF/w (r=-0.75). Moreover, visceral fat reduction was significantly related to weight reduction during aerobic exercise intervention, although a significant visceral fat reduction may occur without significant weight loss. CONCLUSION: These results suggest that at least 10 METs x h/w in aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage, is required for visceral fat reduction, and that there is a dose-response relationship between aerobic exercise and visceral fat reduction in obese subjects without metabolic-related disorders.

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 x 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.