Healthy Young Females Research Articles

Attentional focus modulates physiological response to arousal in a competitive putting task.

Attentional focus during the execution of perceptual motor tasks has been shown to affect performance outcomes. The purpose of this study is to assess the physiological changes prompted by attentional focus in various levels of stress. Thirty-six healthy young males and females were randomized into groups and directed on attentional focus in a staged putting competition scenario intended to elicit competitive anxiety. External focus groups experienced less internal workload at all arousal levels and preserved heart rate variability measures when audiovisual distraction was introduced.

Electroencephalogram of Normotensive Individuals During Sitting and Standing Blood Pressure Measurement Positions.

Background Investigating changes in brain electroencephalogram activity during blood pressure measurement in sitting and standing positions is clinically significant for understanding the neural correlates of postural changes, which may affect cerebral perfusion and autonomic regulation. Shifts in blood pressure can influence visual cortical activity, potentially altering cognitive and sensory processing. This research holds clinical relevance in evaluating disorders like orthostatic hypotension and syncope, where postural changes compromise cerebral blood flow. Furthermore, it can help refine diagnostic protocols and management strategies for neurovascular and autonomic dysfunction. The study also highlighted the possibility of using polygraphs to identify and manage discrepancies in blood pressure measurement caused by posture-induced changes in brain activities for accurate diagnosis. Methodology The electroencephalogram of healthy normotensive female individuals undergoing blood pressure measurements at sitting and standing positions was investigated. Ten healthy young adult females who satisfy the inclusion criteria were selected. Electroencephalographic (EEG) waves were recorded with the aid of Powerlab 26T (ADInstruments Pty Ltd., Bella Vista, Australia). Blood pressure and pulse rate measurements were conducted using a sphygmomanometer and stopwatch. Results During sitting and standing blood pressure positions, diastolic blood pressure and pulse rate were higher when compared to baseline values but the standing blood pressure position showed a higher pulse rate than the sitting blood pressure position. Although alpha wave frequency was higher during both sitting and standing blood pressure measurement positions, the standing blood pressure position caused lower alpha wave frequency when compared with the sitting blood pressure measurement position. While a strong negative correlation was found between alpha wave frequency and pulse rate, beta wave frequency positively correlated with pulse rate during sitting blood pressure measurement position. Furthermore, during standing blood pressure measurement position, the alpha wave did not correlate with pulse rate nor was there a correlation between beta wave frequency and pulse rate. In conclusion, the present study indicated that both sitting and standing blood pressure measurement positions caused a decrease in alpha wave frequency when compared with baseline, but the standing blood pressure measurement position elicited a lower alpha wave frequency when compared with the sitting blood pressure measurement position.

The Effects of Inorganic Nitrate Supplementation on Muscular Power and Endurance Across the Menstrual Cycle.

Oral inorganic nitrate (NO3-) supplementation increases nitric oxide (NO) bioavailability and may improve muscular power in males and females, although data in females is limited. Estrogen increases NO bioavailability and fluctuates throughout the menstrual cycle (MC), with low levels in the early follicular (EF) phase and peaking during the late follicular (LF) phase. The purpose of the present study was to examine the effects of NO3- supplementation on isokinetic peak power, maximal voluntary isometric contraction (MVIC) force, muscular endurance, and recovery from fatigue in healthy young females during the EF and LF phases of the MC. Ten eumenorrheic females were tested in a double-blinded, randomized, placebo-controlled design. Participants consumed ~13mmol NO3-, in the form of 140ml beetroot juice (BRJ), or an identical NO3--depleted placebo (PL), for ~5 days prior to visits and 2 hours prior to testing. Plasma estradiol was elevated in the LF phase, and plasma nitrite and nitrate were elevated in the BRJ condition (p < 0.05). While isokinetic peak power was unchanged, calculated maximal power (Pmax) and maximal velocity (Vmax) was significantly worsened in the BRJ treatment independent of the MC phase (p = 0.02 and 0.03, respectively). Muscular endurance, MVIC, and fatigue recovery were unaltered by BRJ or the MC. These data indicate that NO3- supplementation decreased maximal power and velocity in females and suggest that the benefits of NO3- supplementation previously found in males may not extend to young females.

Artificial Intelligence-Driven Skin Aging Simulation as a Novel Skin Cancer Prevention

Introduction: Skin cancer, a prevalent cancer type among fair-skinned patients globally, poses a relevant public health concern due to rising incidence rates. Ultraviolet (UV) radiation poses a major risk factor for skin cancer. However, intentional tanning associated with sunburns remains a common practice, notably among female adults. Appropriate prevention campaigns targeting children and adolescents are needed to improve sun protection behavior particularly in these age groups. The aim of our study was to investigate if an AI-based simulation of facial skin aging can enhance sun protection behavior in female adults. Methods: In this single-center, prospective, observational pilot study at Department of Dermatology at the University Hospital of Basel, we took photographs of healthy young females’ faces with a VISIA-CR camera (Version 8.2; Canfield Scientific Inc., Parsippany, NJ, USA) between February and March 2021. Digital images were performed in three angles (straight, left 45°, and right 45°). All participants received an AI-based simulation of their facial skin with continuous aging to 80 years. A newly created anonymous questionnaire capturing participants’ sociodemographic data and also tanning and sun protection behavior was completed in pre- and post-aging simulation. To observe long-term effects, a 2-year follow-up was conducted between March and April 2023. Results: The 60 participants (mean age 23.6 ± 2.5 years) evaluated the importance of sun protection significantly higher after skin aging simulation with VISIA-CR camera (p < 0.0001; 95% CI: 8.2–8.8). Post-intervention, 91.7% (55/60) of the females were motivated to reduce UV exposure and to intensify UV protection in the future since the individual UV-dependent risk was perceived significantly higher (p < 0.001; 95% CI: 5.9–6.7). At 2-year follow-up, 96% (24/25) indicated persistent effort reducing UV exposure. The preference for SPF 50+ sunscreen increased to 46.7% (28/65) directly after the skin aging simulation and continued to rise up to 60.0% (15/25) after 2 years. Conclusions: Our data emphasize the potential of AI-assisted photoaging interventions to enhance motivation for UV protection in the short and the long term. We encourage that different age and gender groups are addressed in a personalized, generation-specific manner with the appropriate media and by considering the Hawthorne effect. Campaigns with visual AI support can improve the intent of cancer-preventative behavior.

Prediction of the maximum oxygen consumption (VO2max) for young Saudi females using exercise parameters.

Maximum oxygen consumption (VO2max), an essential indicator of integrated function of the cardiovascular, respiratory, and muscular systems, is an excellent predictor of all-cause morbidity and mortality. Direct measurement is a sophisticated procedure which for some individuals is difficult to perform. The use of international formulae leads to overestimation or underestimation of values. Therefore, the present study aimed to generate a best-fit VO2max prediction formula for young Saudi females. One hundred and two randomly selected young healthy Saudi females (19-25 years) with normal body mass index (18.5-24.99 kg m-2) and sedentary lifestyle underwent maximum cardiopulmonary exercise testing on cycle ergometer when using breath-by-breath analyzing system. Hemodynamic and ventilatory parameters were assessed before and during the maximum exercise. Significantly correlated exercise and nonexercise parameters enterd in multiple linear regression analysis to find the best-fit model, and used to generate a VO2max prediction formula. The mean measured VO2max was 1449.1 ± 233.92 ml min-1. The VO2max prediction formula was 1304.193 ± 17.902 × body weight + 43.857 × time until exhaustion - 6.83 × maximum heart rate. The mean calculated VO2max was 1449.14 ± 143.97 ml min-1. No statistically significant difference was observed between the measured and calculated VO2max. The Bland-Altman test for the limit of agreement was performed and showed good agreement between the two values with a minute proportional bias. The standard error of the estimate was 156.34, which is approximately 10.6% of the mean measured VO2max. Reliability analysis yielded a Cronbach's alpha of 0.709. This study presents a reliable and valid VO2max prediction formula for young Saudi females. This nationally generated formula is far more representative of the VO2max value than international formulae. We recommend the implementation of this formula and an investigation of its validity in other Saudi population groups.

Investigating the Immediate Effects of Static and Dynamic Stretching Exercises of Lower Extremities Muscles on Core Stability in Young Healthy Females

Introduction: This study investigates the immediate effects of warm-up exercises, specifically static and dynamic stretches for the lower extremities, on strength, endurance, flexibility, motor control, and core stability function in young, healthy females. Materials and Methods: A total of 60 healthy, active women aged 19-30 years were randomly divided into three groups as follows: Static stretching (SS), dynamic stretching (DS), and a control group (CG), which received no exercises. Evaluation methods for core stability included strength, endurance, sit-and-reach, Y-balance, and bilateral squat tests. Meanwhile, these tests were conducted before and after the prescribed exercise protocols. Results: Both the SS and DS groups experienced significant increases in all core stability components compared to their baseline values (P&lt;0.05). Meanwhile, the analysis of variance/ analysis of covariance indicated that immediately after performing the stretching exercises, the SS and DS groups exhibited significantly greater improvements in parameters, such as strength, endurance, flexibility, and balance tests (except for the posterior-medial direction) when compared to the CG (P&lt;0.05). Regarding functional parameters after the exercises, there were no statistically significant differences between the study groups (P&gt;0.05). In addition, dynamic exercises demonstrated a higher effectiveness than static exercises for most parameters (P&lt;0.05). Conclusion: Warm-up exercises, involving both static and dynamic stretches for lower limb muscles appear to have an immediate positive impact on core stability parameters. In sports that demand strong trunk muscles and balance, the dynamic protocol may be more effective

Novel biomarkers in the saliva of healthy young males and females in a randomized crossover study on sedentary time: An exploratory analysis.

Several known biomarkers have been used to understand the physiological responses of humans to various short and long-term interventions such as exercise or dietary interventions. However, little exploratory work has been conducted to identify novel biomarkers in human saliva that could enable non-invasive physiological research to understand acute responses to interventions such as reducing sedentary time. The purpose of this study was to identify novel biomarkers in the saliva (cytokines, growth factors and vascular factors) that respond to prolonged (4 hours) and interrupted sitting (4 hours of sitting interrupted by 3 minutes of walking at 60% of maximal heart rate every 27 minutes) in young, healthy males and females. We also sought to determine whether responsive biomarkers would differ by sex. Participants (n = 24, 21.2 ± 2.2 years, 50% female) completed a prolonged sitting (PS) session and an interrupted sitting (IS) session in random order. Individual saliva samples were pooled into a male sample and a female sample to identify responsive biomarkers using a human cytokine antibody membrane array (42 targets). Several novel biomarkers were responsive in both sexes (e.g., IL-8, Angiogenin, VEGF, and EGF), in females only (e.g., TNF-α and IL-13), and in males only (e.g., IL-3, RANTES, and IL-12p40/p70). Importantly, several biomarkers appear to be responsive to the 4-hour prolonged and interrupted sitting sessions (e.g., TNF-α, IL-8, IL-3, RANTES, EGF, Angiogenin, and VEGF). This work highlights new directions for researchers aiming to investigate the effect of short-term or acute interventions on different physiological pathways using non-invasive methods. Our work clearly indicates that human saliva samples can provide a wealth of insight into physiological responses, and that a number of biomarkers can be used to understand changes induced by acute interventions such as interrupting prolonged sitting.

Blood pressure and ECG variables of healthy young males and females participating in moderate aerobic exercise

IntroductionChanges in blood pressure and electrocardiogram are important factors that determine exercise testing. This study investigated blood pressure and electrocardiogram (ECG) changes in healthy young adults after performing acute moderate aerobic exercise protocols. MethodsForty young healthy untrained non-athletes, twenty males and twenty females (age, 25 ± 5.6 years; body weight, 65 ± 4.0 kg; body height, 176.9 ± 2.5 cm) were recruited for the study. The exercise regimen was acute moderate exercise for 20 min on a treadmill consistently for 14 days daily at the speed of 13 km/h. The body weight, blood pressure, and electrocardiograph were measured before and after exercise. ResultsThere was a significant reduction (P < 0.05) in body weight (59 ± 3.2 kg) of female participants after 14 days of aerobic exercise relative to their baseline mean value (63 ± 2.9 kg). The systolic blood pressure decreased (P < 0.05) in males (117 ± 1.1 mmHg) and females (117 ± 1.0 mmHg) when compared to the mean baseline values in males (127 ± 1.3 mmHg) and females (128 ±0 .3 mmHg). The diastolic blood pressure also decreased (P < 0.05) in male (71 ± 0.88 mmHg) participants after exercise when compared to the baseline mean values (79 ± 1.2 mmHg) while there was no change in diastolic blood pressure of females. The ECG parameters remained unchanged, while the heart rate (75 ± 1.3 beats/min) increased (P < 0.05) after exercise in all participants relative to the baseline (69 ± 2 beats/min). ConclusionThe results suggest that moderate aerobic exercise normalized blood pressure and electrical activity of the heart while reducing heart rate after 14 days of consistent aerobic exercise in healthy individuals.

Cooling collars incorporated with PCM packs and gels to improve indoor thermal comfort in healthy young females

The human neck is one of the most thermally sensitive body regions to nociceptive stimuli. Neck cooling has been extensively researched to improve athletic performance in the heat. However, there has been very little research into the use of conductive neck cooling for indoor thermal comfort. We thereby designed three ultralight cooling collars with cooling gels or phase change materials (GEL6, PCM15, and PCM18). Their cooling performance on thermal comfort enhancement of 14 healthy young female participants under two warm indoor temperatures (28 °C and 30 °C) was investigated. Thermophysiological and perceptual responses, including skin temperature, heart rate, sweating, thermal sensation vote (TSV), thermal comfort vote (TCV), and thermal preference vote (TPV), were extensively studied. Results showed that, in contrast to GEL6, PCM15 and PCM18 significantly decreased the neck skin temperature, with PCM15 exhibiting the greatest reduction of 4.37 °C at 28 °C. PCM15 and PCM18 significantly decreased overall and local TSVs while also increasing overall and local TCVs (all p < 0.05), thus they could maintain >80 % occupant satisfaction at 28 °C. At 30 °C indoor temperature, however, none of these three cooling collars were found to meet the 80 % occupant satisfaction criterion. When compared to GEL6, PCM15 and PCM18 were found to only significantly reduce local TSVs at the head and neck (all p < 0.05). In sum, PCM15 and PCM18 have the potential to increase acceptable HVAC summer cooling setpoint temperature by 2.5 °C, from 25.5 °C to 28.0 °C, leading to a 25 % reduction in building cooling energy consumption.

The Impact of Induced Acceleration Perturbations in Selected Phases of the Gait Cycle on Kinematic and Kinetic Parameters

Background: The prevalence of falls among the older population underscores the imperative of comprehending human adaptations to gait perturbations. Dual-belt treadmills offer a controlled setting for such investigations. The purpose of this study was to examine the effect of the acceleration of one belt of the treadmill during three different phases of the gait cycle on kinematic and kinetic parameters and relate these changes to unperturbed gait. Methods: Twenty-one healthy young females walked on a treadmill in a virtual environment, in which five unexpected perturbations were applied to the left belt at the Initial Contact (IC), Mid Stance (MS), and Pre-Swing (PS) phase of the gait cycle. Data from the undisturbed gait and the first disturbance of each trial were extracted for analysis. Results: All perturbations significantly affected the gait pattern, mainly by decreasing the knee extension angle. The perturbation in the IC phase had the most significant effect, resulting in a 248.48% increase in knee flexion torque. The perturbation in the MS phase mainly affected plantar flexion torque, increasing it by 118.18%, while perturbation in the PS phase primarily increased the hip extension torque by 73.02%. Conclusions: The presence of perturbations in the IC and PS phases caused the most aggressive and significant changes in gait parameters.

Balance performance among horseback-rider compared to non-horseback-rider women in Saudi Arabia: A cross-sectional study.

Horseback riding requires adapting to constant changes in balance conditions, maintaining equilibrium on the horse, and preventing falls. However, differences in balance performance among horseback riders and non-rider-healthy young women in Saudi Arabia have not been explored. This study investigates whether horseback-rider women would perform better on static and dynamic balance tests than non-rider women. Also, the study examined the effect of years of horseback riding on balance performance in the rider group. Twenty healthy young females participated in the study using a convenience sampling method. Ten were riders, and ten were non-riders. Static and dynamic balance tests, including the Berg balance scale (BBS), timed up and go (TUG), and unipedal stance test (UPST), was obtained from all subjects. Descriptive and inferential statistics were used to compare balance performance between the horseback riders and non-riders groups. The horseback-rider group had statistically significantly higher scores on both the static and dynamic tests than non-riders: BBS test (Z = -2.537, P = .011), TUG (t = -3.889, P = .001), and unipedal stance test with the eyes open and closed (t = 14.048, t = 13.639, P = .000). Our rider sample did not show a statistically significant correlation between years of riding and balance scores. The horseback riders have greater static and dynamic balance abilities than non-riders. Further study is needed to compare the balance performance between experienced riders versus beginners among healthy adults in Saudi Arabia.

Oral hormonal contraceptives and cardiovascular risks in females.

Oral hormonal contraception (OHC) is a widely employed method in females for the prevention of unintended pregnancies, as well as for the treatment of menstrual disorders, endometriosis, and polycystic ovarian syndrome. However, it is believed that with OHCs use, some females may have higher risk of cardiovascular diseases, such as hypertension, diabetes, myocardial infarction, thrombosis, and heart failure. Although such risks are infrequently detected in healthy young females with the use of oral contraceptives, slightly elevated risks of cardiovascular diseases have been observed among reproductive-aged healthy females. However, prolonged use of OHC has also been claimed to have protective cardiac effects and may contribute to reduced risk of cardiovascular disease. In fact, the debate on whether OHC administration increases the risk of cardiovascular diseases has been ongoing with inconsistent and controversial viewpoints. Nevertheless, a great deal of work has been carried out to understand the relationship between OHC use and the occurrence of cardiovascular risk in females who use OHC for preventing the unwanted pregnancy or treatment of other disorders. Therefore, in this review we summarize the most recent available evidence regarding the association between the use of oral hormonal contraceptives and the risk for cardiovascular disease in females who are using OHC to prevent unintended pregnancy.

Aging in females has minimal effect on changes in celiac artery blood flow during dynamic light-intensity exercise.

Blood flow to the active muscles and arterial blood pressure (ABP) increase during dynamic exercise, whereas blood flow to inactive organs (e.g., splanchnic organs and inactive limbs) declines. Aging leads to exaggerated ABP responses to exercise in females, but whether this is related to greater splanchnic vasoconstriction is unknown. This study sought to clarify the effect of aging in females on celiac artery blood flow during dynamic light-intensity exercise. Twelve healthy young females (YF: 20 ± 2 yr, mean ± SD) and 12 healthy older females (OF: 71 ± 4 yr) performed dynamic knee-extension and knee-flexion exercises at 30% of heart rate reserve for 4 min. The absolute changes from baseline (Δ) for mean arterial blood pressure (MAP), celiac artery mean blood flow (celMBF), and celiac vascular conductance (celVC) during exercise were calculated. ABP was measured using an automated sphygmomanometer, and celMBF was recorded by Doppler ultrasonography. The increase in MAP during exercise was greater in OF than in YF (YF: +14 ± 7 mmHg, OF: +24 ± 13 mmHg, P = 0.028). The celMBF decreased during exercise in both groups, but there was no significant difference in the response between YF and OF (YF: -93.0 ± 66.1 mL/min, OF: -89.6 ± 64.0 mL/min, P = 0.951). The celVC also decreased during exercise and remained lower than baseline during exercise. However, the response was not different between YF and OF (YF: -1.8 ± 1.0 mL/min/mmHg, OF: -1.5 ± 0.6 mL/min/mmHg, P = 0.517). These results demonstrate that aging in females has minimal influence on splanchnic artery hemodynamic responses during dynamic light-intensity exercise, suggesting that exaggerated ABP responses during exercise in OF are not due to greater splanchnic vasoconstriction.NEW & NOTEWORTHY During exercise, the splanchnic arteries vasoconstrict, contributing to blood flow redistribution and the blood pressure response. Blood pressure responses to exercise are exaggerated with aging in females; however, the physiological mechanism responsible has not been clarified. We show that celiac artery blood flow changes during light-intensity dynamic exercise do not differ with age in females. This indicates the exaggerated blood pressure to exercise with aging is likely not due to a difference in splanchnic vasoconstriction.

Reflex sympathetic activation to inspiratory muscle loading is attenuated in females relative to males.

Intense inspiratory muscle work can evoke a metabolite-stimulated pressor reflex, commonly referred to as the respiratory muscle metaboreflex. When completing similar relative and absolute levels of inspiratory work, females have an attenuated blood pressure response. We sought to test the hypothesis that the lower blood pressure response to the respiratory muscle metaboreflex in females is associated with a reduced sympathetic response. Healthy young (26 ± 4 yr) males (n = 9) and females (n = 7) completed two experimental days. On day 1, participants completed pulmonary function testing and became familiarized with an inspiratory pressure-threshold loading (PTL) task. On the second day, balloon-tipped catheters were placed in the esophagus and stomach to measure pleural and gastric pressures, and transdiaphragmatic pressure was calculated. A microelectrode was inserted into the fibular nerve to quantify muscle sympathetic nerve activity (MSNA), and participants then completed isocapnic PTL to task failure. There was a significant sex-by-time interaction in the mean arterial pressure (MAP, P = 0.015) and burst frequency (P = 0.039) response to PTL. Males had a greater rise in MAP (Δ21 ± 9 mmHg) than females (Δ13 ± 5 mmHg, P = 0.026). Males also demonstrated a greater rise in MSNA burst frequency (Δ18 ± 7 bursts/min) than females (Δ10 ± 5 bursts/min, P = 0.015). The effect of sex was observed despite females and males completing the same magnitude of diaphragm work throughout the task (P = 0.755). Our findings provide novel evidence that the lower blood pressure response to similar relative and absolute inspiratory muscle work in females is associated with lower sympathetic activation.NEW & NOTEWORTHY The blood pressure response to high levels of inspiratory muscle work is lower in females and occurs alongside a reduced sympathetic response. The reduced blood pressure and sympathetic response occur despite males and females performing similar levels of absolute inspiratory work. Our findings provide evidence that sex differences in the respiratory muscle metaboreflex are, in part, sympathetically mediated.

Interactions Between Reproductive Hormones and Neuro-Vascular Regulation During the Cold Pressor Test in Young Females

Recently, we reported that muscle sympathetic nerve activity (MSNA) is not predictive of vascular nor blood pressure outcomes during the cold pressor test (CPT) in young healthy females. Instead, we observed substantial variability in vascular responses to the CPT which ranged widely from decreases in blood flow and vascular conductance to increases in these same outcomes. Interindividual differences in circulating reproductive hormones may account for this female-specific variability in vascular responses to acute elevations in MSNA. Therefore, the purpose of this study was to test the hypothesis that reproductive hormones account for variability in MSNA, femoral blood flow (FBF), and femoral vascular conductance (FVC) during the CPT in females. We retrospectively assessed data from 9 young healthy females (age: 24±3 years) in the low hormone phase of their menstrual cycle (days 1-5). Intravenous blood samples were obtained and prospectively analyzed to assess concentrations of circulating reproductive hormones (radioimmunoassay). Integrated peroneal MSNA (microneurography; NeuroAmpEX, ADI) was quantified at rest and during a 3-minute hand CPT. Mean arterial pressure (MAP) was measured beat-by-beat (Finometer Midi, FMS) and duplex vascular ultrasound was used to measure FBF; FVC was quantified as FBF/MAP (mL/min/mmHg). All variables are expressed as the difference between the average CPT value and the average baseline value. CPT-induced changes in MSNA burst incidence (bursts/100hb) were not related to [17-beta-estradiol] (R2=0.05; P=0.60), [progesterone] (R2=0.11, P=0.47), or [free testosterone] (R2=0.01, P=0.81). Similarly, changes in FBF and FVC were not related to [17-beta-estradiol] (FBF: R2=0.04, P=0.67; FVC: R2=0.01, P=0.80) or [progesterone] (FBF: R2=0.04, P=0.67; FVC: R2=0.09, P=0.51). However, there was a negative correlation between [free testosterone] and the changes in both FBF (R2=0.69, P=0.02) and FVC (R2=0.66, P=0.03). In other words, females with higher free testosterone demonstrated larger decreases in FBF and FVC during the CPT relative to those with lower free testosterone concentrations. These data suggest that circulating free testosterone may act to increase the vasoconstrictive consequences of MSNA in females, and may account for the previously observed variability in vascular responses to MSNA during acute stress. This project was funded by: NSERC and FRQ-S. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Resting Beat-to-Beat Blood Pressure Variability in Young, Healthy, Non-Hispanic Black Females

Background: Non-Hispanic Black (BL) individuals are at greater risk for cardiovascular disease and hypertension compared to other racial groups. Beat-to-beat blood pressure variability (BPV) is a known predictor of adverse cardiovascular outcomes. Our laboratory recently reported an augmented resting beat-to-beat BPV in non-Hispanic BL males compared to their White (WH) male counterparts. However, racial differences in beat-to-beat BPV between non-Hispanic BL and non-Hispanic WH females are unknown. Therefore, we tested the hypothesis that young, healthy, non-Hispanic BL females have elevated resting beat-to-beat BPV compared to healthy age and body mass index matched WH females. Methods: We studied 12 young healthy non-Hispanic BL females (20 ± 2 years, 25.2 ± 4 kg/m2, mean ± standard deviation) and 12 young healthy non-Hispanic WH females (22 ± 3 years, 22.7 ± 3 kg/m2; P = 0.13 and P = 0.10, respectively). Beat-to-beat arterial blood pressure (finger photoplethysmography) was continuously recorded during ten minutes of supine rest. Mean, standard deviation (SD), range, coeffcient of variation, and average real variability (ARV) were calculated for systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Results: Resting absolute SBP (BL: 113 ± 12 mmHg; WH: 112 ± 7 mmHg; P = 0.98), DBP (BL: 69 ± 7 mmHg; WH: 66 ± 5 mmHg; P = 0.22), and MAP (BL: 83 ± 7 mmHg; WH: 81 ± 4 mmHg; P = 0.48) were not different between groups. Likewise, beat-to-beat SBP SD (BL: 3.5 ± 0.78 mmHg; WH: 4.0 ± 1.16 mmHg; P = 0.21), range (BL: 21 ± 5 mmHg; WH: 24 ± 6 mmHg; P = 0.26), coeffcient of variation (BL: 3.01 ± 0.82%; WH: 3.56 ± 0.96%; P = 0.20), and ARV (BL: 2.02 ± 0.46; WH: 2.26 ± 0.6; P = 0.27) were not different between BL and WH females. There were also no differences in any of the beat-to-beat BPV measures for DBP or MAP between BL and WH females (all P &gt; 0.05). Conclusion: In contrast to our hypothesis and previous work in non-Hispanic BL males, these preliminary data suggest that beat-to-beat BPV is not different between non-Hispanic BL and WH females. This work was supported by the College of Nursing and Health Innovation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

NADPH oxidase-derived reactive oxygen species regulates adipose tissue lipolysis in humans

There is mounting evidence suggesting that reactive oxygen species (ROS) generated by NADPH oxidase (NOX) regulate physiological processes, as NOX has been shown to promote increases in lipolysis in cultured adipocytes. PURPOSE: To determine the mechanisms by which NOX stimulates adipose tissue lipolysis. METHODS: Young healthy females (n = 17; mean ± SD; age: 21.7 ± 5 years; body mass index: 22.2 ± 3.8 kg/m2) participated in this study. Participants underwent microdialysis and hyperinsulinemic-euglycemic clamp (clamp) procedures. Three microdialysis probes were inserted into subcutaneous abdominal adipose tissue to monitor local adipose tissue ROS (H2O2) production and lipolysis (as indicated by dialysate glycerol). To determine whether NOX stimulates lipolysis via distinct signaling pathways, microdialysis probes were perfused with either isoproterenol (Iso; β-adrenergic agonist to stimulate canonical lipolysis signaling) or atrial natriuretic peptide (ANP to stimulate non-canonical lipolysis signaling), then perfused with a local NOX inhibitor (apocynin). A control probe was perfused with apocynin but without any agonists of lipolysis. The microdialysis procedures were then repeated under hyperinsulinemic conditions during the same study visit. RESULTS: In the fasted state, dialysate H2O2 concentrations were lower in the control and Iso probes upon apocynin perfusion (control probe without apocynin: 1.06 ± 0.5 μM, with apocynin: 0.62 ± 0.2 μM; p = 0.005; Iso probe without apocynin: 1.01 ± 0.4 μM, with apocynin: 0.66 ± 0.2 μM; p = 0.003). Apocynin perfusion did not alter dialysate H2O2 concentrations in the ANP probe under the fasted state (p = 0.11). Dialysate glycerol concentrations did not change upon apocynin perfusion under any of the microdialysis probe conditions in the fasted state (p &gt; 0.05). During the clamp, apocynin perfusion resulted in lower dialysate H2O2 concentrations in the three conditions (control probe without apocynin: 1.22 ± 0.6 μM, with apocynin: 0.75 ± 0.3 μM; p = 0.03; Iso probe without apocynin: 1.55 ± 0.8 μM, with apocynin: 0.79 ± 0.3 μM; p = 0.01; ANP probe without apocynin: 1.55 ± 0.6 μM, with apocynin: 0.92 ± 0.3 μM; p = 0.03). Dialysate glycerol concentrations were lower in the Iso probe upon apocynin perfusion during the clamp (Iso probe without apocynin: 124.7 ± 38 μM, with apocynin: 90.9 ± 25 μM; p = 0.003). CONCLUSIONS: This study presents adipose tissue NOX as a source of in vivo ROS production in human participants. In addition, we reveal a novel mechanism of NOX in adipose tissue function whereby NOX exerts increases in β-adrenergic-mediated lipolysis during hyperinsulinemia. Our findings highlight the roles of ROS as signaling mediators and suggest that an imbalance between NOX activity and insulin action on adipose tissue could negatively affect systemic fatty acid metabolism. Porter Pre-doctoral Fellowship from the American Physiological Society and an NIH National Research Service Award (F31HL154642). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Characterizing the association of systemic estradiol levels and transcriptional markers of skeletal muscle regeneration in healthy young females

Recent research indicates estradiol's (E2) role in modulating skeletal muscle regeneration. E2 has been observed to enhance myogenic capacity by upregulating myogenic factors and downregulating proteolytic factors[1,2]. The extracellular matrix (ECM) of skeletal muscle also influences regeneration due to its interaction with muscle progenitor cells [5]. Cell and animal studies observed E2's ability to impact on collagen (COL) 1, 3, and 4 production [3,4]. However, limited data from physiologically relevant human models exploring myogenic markers and ECM throughout the menstrual cycle are available. We hypothesize that higher systemic E2 levels will correspond to an increased regenerative gene expression signature. Understanding this relationship is crucial for assessing how E2 levels affect muscle healing in eumenorrheic women and E2’s potential as a therapeutic molecule for enhancing muscle repair. The study included 19 pre-menopausal women aged 18-39 undergoing hip surgery at UT Southwestern (UTSW) Medical Center. This study was approved by the UTSW IRB and conducted in accordance with the Declaration of Helsinki. Blood and muscle biopsies were collected for hormone and gene analysis. Only subjects in the follicular phase (n=12) were included to minimize progesterone's influence. Investigated genes included myogenic factors (MYOD1, MYF5, MYF6, MYOG), proteolytic factors (FOXO3, MuRF1), and COL genes (COL1a1, COL-3a1, COL-4a1, COL-6a1). E2 levels ranged from 26-356 pg/mL, with negligible progesterone levels, consistent with the follicular phase. While no significant relationships were found between myogenic and proteolytic genes, MYF6 exhibited a positive relationship with E2 (p=0.07), while MuRF1 showed a negative one (p=0.09). COL 1, 3, and 6 gene expressions had no significant relationship with E2, but COL 4 exhibited a statistically significant positive relationship (p=0.04) with E2 concentration. Though no statistically significant relationships emerged between myogenic or proteolytic gene expression and E2 levels, there were notable trends toward significance for MYF6 and MuRF1. MYF6, recognized for its role in myogenic differentiation, is implicated in maintaining the satellite cell pool by promoting myokine secretion[6]. In contrast, MuRF1 is a critical component in muscle atrophy[7]. COL4 expression was significantly associated with E2 levels (p=0.4). It is hypothesized that COL4 enhances IGF1-activated myoblast migration, differentiation, and fusion [5]. These findings suggest a potential link between elevated E2 levels and an enhanced regenerative capacity. These findings indicate that higher E2 conditions may create a favorable environment for muscle recovery. Future research should increase sample size and examine protein levels of these factors.

CYP450 Inhibition on Cerebral Hemodynamics in Healthy, Young Males and Females During Simulated Hypovolemia

Animal models have shown that cytochrome P450 2C9 (CYP450) is involved in vascular control within the cerebrovasculature. However, the role sex plays on CYP450 within human cerebral circulation has not been examined. PURPOSE: To determine the contribution of CYP450 to cerebrovascular hemodynamics between healthy young males and females at rest and during mild simulated hypovolemia. METHODS: 18 subjects (9 females, tested during days 1-5 of early follicular phase) participated in 1 familiarization and 2 experimental visits. During experimental visits, subjects ingested a CYP450 inhibitor (fluconazole, FLZ 150mg) or placebo (PLC, 250mg microcrystalline cellulose) in a randomized, single-blind, crossover design. Following ingestion and 120 minutes of supine rest, middle cerebral artery velocity (MCAv, cm/s, Transcranial Doppler) and mean arterial pressure (MAP, mmHg, finger photoplethysmography) were continuously measured during 5 minutes of supine rest and 5 minutes of lower-body negative pressure (LBNP, -20mmHg). Cerebrovascular conductance index (CVCi) was calculated as MCAv/MAP. RESULTS: Means ± SD. Resting values for all variables were not different between treatments (p &gt; 0.05). Therefore, all data are presented as a change (Δ) from rest to LBNP. There was no treatment*time*sex effect for MCAv or CVCi (p = 0.52, pη2 = 0.08; p = 0.34, pη2 = 0.06, respectively). MCAv responded similarly to LBNP between sexes within PLC and FLZ with a low-to-moderate effect (M -4.2 ± 5.2 vs. F -2.4 ± 7.3, p = 0.63, r = 0.11; M -4.2 ± 6.2 vs. F -8.1 ± 6.3, p = 0.06, r = 0.45, respectively). Similarly, male and female CVCi responses to LBNP were similar within treatments with a low effect (PLC M -0.04 ± 0.05 vs. -0.02 ± 0.08, p = 0.69, r = 0.09; FLZ M -0.06 ± 0.06 vs. -0.08 ± 0.05, p = 0.31, r = 0.24). Two one-sided testing (TOST) analysis, used to assess equivalence between groups (1), revealed that the differences between PLC and FLZ ΔMCAv and ΔCVCi were non-equivalent between the sexes (Mean = 5.67, t(13.84) = 0.42, p = 0.55; Mean = 0.05, t(15.02) = 0.34, p = 0.63, respectively). CONCLUSION: Although no significant differences were seen between sexes, small-to-moderate effect sizes and TOST analysis suggest male and female hemodynamic responses to LBNP are not equal following CYP450 inhibition. These data argue that CYP450 may have differential contributions to cerebral vascular control between the sexes and further exploration is warranted. 1. O’Brien MW, Kimmerly DS. Is “not different” enough to conclude similar cardiovascular responses across sexes? American Journal of Physiology-Heart and Circulatory Physiology 322: H355–H358, 2022. doi: 10.1152/ajpheart.00687.2021. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Habitual Sleep and Muscle Sympathetic Nerve Activity in Humans

Short habitual sleep duration and inadequate sleep effciency are associated with poor cardiovascular health. Although a potential mediator of this relationship is augmented sympathetic activity, only one study to date has assessed the relationship between objectively measured habitual sleep duration and direct muscle sympathetic nerve activity (MSNA) in humans. Moreover, the proportion of resting MSNA that can be independently explained by habitual sleep while controlling for other key variables remains unknown. The purpose of the present study was to assess the independent relationship between total sleep time (TST), sleep effciency (SE), and MSNA in a large population of young males and females. We hypothesized that short TST and low SE would be associated with elevated MSNA and blood pressure. A minimum 7 days of at-home, objective actigraphy sleep monitoring was collected in 66 healthy young adults (35 males, 31 females; 24±1 years; 26±1 kg/m2). In each participant, the average of three seated brachial blood pressures was recorded and used to determine resting mean arterial blood pressure (MAP). All participants underwent an autonomic function test that simultaneously assessed heart rate (HR, electrocardiogram), beat-to-beat blood pressure (finger plethysmography) and MSNA (microneurography) during 10 minutes of quiet rest. Resting MAP (83±1 mmHg), HR (64±1 beats/min) and MSNA (19±1 bursts/min) were normally distributed. Habitual TST was significantly correlated with MSNA (r=-0.265, p=0.032), but was not associated with resting MAP (r=-0.153, p=0.219) or HR (r=-0.205, p=0.098). SE was not associated with any of the outcome variables (all p&gt;0.25). Multiple regression was used to test the independent relationship between TST, MAP, HR, and MSNA while accounting for effects of age, sex, and body mass index (BMI). The regression model significantly predicted MAP (R2=0.253, p=0.001) and MSNA (R2=.211, p=0.005), but not HR (R2=.047, p=0.560). TST did not independently explain any additional variance in MAP (ΔR2=0.004, p=0.562) beyond that ascribed to the effects of age, sex, and BMI. In contrast, TST independently explained an additional 5% of the variance in MSNA (ΔR2=0.053, p=0.048). In a large sample of healthy young males and females, our results indicate that habitual TST explains only a minor proportion of the observed variance in resting MSNA between participants. NIH (AA-024892). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.