Effects of isometric leg training on ambulatory blood pressure and morning blood pressure surge in young normotensive men and women.

Despite the reported association between diurnal variations in ambulatory blood pressure (BP) and elevated cardiovascular disease risk, little is known regarding the effects of isometric resistance training (IRT), a practical BP-lowering intervention, on ambulatory BP and morning BP surge (MBPS). Thus, we investigated whether (i) IRT causes reductions in ambulatory BP and MBPS, in young normotensives, and (ii) if there are any sex differences in these changes. Twenty normotensive individuals (mean 24-h SBP = 121 ± 7, DBP = 67 ± 6 mmHg) undertook 10-weeks of bilateral-leg IRT (4 × 2-min/2-min rest, at 20% maximum voluntary contraction (MVC) 3 days/week). Ambulatory BP and MBPS (mean systolic BP (SBP) 2 h after waking minus the lowest sleeping 1 h mean SBP) was measures pre- and post-training. There were significant reductions in 24-h ambulatory SBP in men (- 4 ± 2 mmHg, P = 0.0001) and women (- 4 ± 2 mmHg, P = 0.0001) following IRT. Significant reductions were also observed in MBPS (- 6 ± 8 mmHg, p = 0.044; - 6 ± 7 mmHg, P = 0.019), yet there were no significant differences between men and women in these changes, and 24-h ambulatory diastolic BP remained unchanged. Furthermore, a significant correlation was identified between the magnitude of the change in MBPS and the magnitude of changes in the mean 2-h SBP after waking for both men and women (men, r = 0.89, P = 0.001; women, r = 0.74, P = 0.014). These findings add further support to the idea that IRT, as practical lifestyle intervention, is effective in significantly lowering ambulatory SBP and MBPS and might reduce the incidence of adverse cardiovascular events that often occur in the morning.

Blood pressure-lowering efficacy of a 6-week multi-modal isometric exercise intervention.

Isometric exercise training (IET) is an effective method for reducing resting blood pressure (BP). To date, no research studies have been conducted using multiple exercises within an IET intervention. Previous research has suggested that varied exercise programmes may have a positive effect on adherence. Therefore, this randomized controlled study aimed to investigate the BP-lowering efficacy of a multi-modal IET (MIET) intervention in healthy young adults. Twenty healthy participants were randomized to an MIET [n = 10; four women; SBP 117.9 ± 6.9 mmHg; DBP 66.3 ± 5.1 mmHg] or control (CON) group (n = 10; five women; SBP, 123.3 ± 10.4 mmHg; DBP, 77.3 ± 6.7 mmHg). The MIET group completed three sessions per week of 4, 2-min isometric contractions, with a 1-min rest between each contraction, for 6 weeks. Resting BP and heart rate (HR) were measured at baseline and post-intervention. Pre-to-post intervention within-group reductions in resting BP were observed (SBP: 5.3 ± 6.1 mmHg, DBP: 3.4 ± 3.7 mmHg, MAP: 4.0 ± 3.9 mmHg, HR: 4.8 ±6 .6 bpm), although clinically relevant (≥2 mmHg), these changes were not statistically significant. Significant (p < 0.05) between-group differences were found between the intervention and control groups, indicating that the MIET intervention has a greater BP-lowering effect compared to control. The clinically relevant post-training reductions in resting BP suggest that MIET may be a promising additional IET method for hypertension prevention. These findings; however, must be interpreted with caution due to the small sample size and the non-clinical cohort.

Cardiopulmonary Exercise Testing Following Open Repair for a Proximal Thoracic Aortic Aneurysm or Dissection.

PURPOSE: There are limited data on cardiopulmonary exercise testing (CPX) and cardiorespiratory fitness (CRF), following open repair for a proximal thoracic aortic aneurysm or dissection. The aim was to evaluate serious adverse events, abnormal CPX event rate, CRF (peak oxygen uptake, (Equation is included in full-text article.)O2peak), and blood pressure. METHODS: Patients were retrospectively identified from cardiac rehabilitation participation or prospectively enrolled in a research study and grouped by phenotype: (1) bicuspid aortic valve/thoracic aortic aneurysm, (2) tricuspid aortic valve/thoracic aortic aneurysm, and (3) acute type A aortic dissection. RESULTS: Patients (n = 128) completed a CPX a median of 2.9 mo (interquartile range: 1.8, 3.5) following repair. No serious adverse events were reported, although 3 abnormal exercise tests (2% event rate) were observed. Eighty-one percent of CPX studies were considered peak effort (defined as respiratory exchange ratio of ≥1.05). Median measured (Equation is included in full-text article.)O2peak was <36% predicted normative values (19.2 mL·kgmin vs 29.3 mLkgmin, P < .0001); the most marked impairment in (Equation is included in full-text article.)O2peak was observed in the acute type A aortic dissection group (<40% normative values), which was significantly different from other groups (P < .05). Peak exercise systolic and diastolic blood pressures were 160 mm Hg (144, 172) and 70 mm Hg (62, 80), with no differences noted between groups. CONCLUSIONS: We observed no serious adverse events with an abnormal CPX event rate of only 2% 3 mo following repair for a proximal thoracic aortic aneurysm or dissection. (Equation is included in full-text article.)O2peak was reduced among all patient groups, especially the acute type A aortic dissection group, which may be clinically significant, given the well-established prognostic importance of reduced cardiorespiratory fitness.

Blood pressure lowering effects of a novel isometric exercise device following a 4-week isometric handgrip intervention.

Background: Hypertension is the leading risk factor for global mortality. Isometric resistance exercise training reduces blood pressure (BP). However, the protocols used are often limited by cost/immobility and the use of rigid exercise modalities. In response, a novel more versatile, isometric exercise (IE) device, the IsoBall (IB) was created. Purpose: The aim of this study was to test the BP-lowering effectiveness of this prototype. Methods: Twenty-three healthy participants (29.10±2.19 years old, 173.95±3.83 cm, 75.43±5.06 kg, SBP 127.10±10.37 mmHg, DBP 70.40±6.77 mmHg) were randomly allocated to either a control group (CON) or 2 isometric handgrip (IHG) training groups that used the Zona plus (ZON) and IB devices. The intervention groups completed 3 sessions each week of 4, 2 min IHG at 30% maximal voluntary contraction, with a 1-min rest, for 4 weeks. Resting BP, heart rate (HR) and IHG strength were measured in all groups at baseline and postintervention. Results: Postintervention systolic BP (SBP) was significantly lower in both ZON (114.5±8.2 mmHg, p = 0.000) and IB (119.9±7.0 mmHg, p = 0.000) compared to control (131.0±12.4 mmHg). Postintervention diastolic BP (DBP) was reduced in both intervention groups (ZON 66.6±7.4 mmHg, p = 0.004; IB 65.7±10.0 mmHg, p = 0.012) compared to CON (71.1±8.8 mmHg). Mean arterial pressure (MAP) was reduced in both groups (ZON 82.6±6.8 mmHg, p = 0.000; IB 84.3±9.1 mmHg, p = 0.000) compared to control (91.0±9.7 mmHg). No significant changes were seen in HR or strength (p > 0.05). Conclusion: The results of this study indicate that both the ZON and IB devices elicit significant SBP, DBP and MAP reductions. Despite the ZON group having larger reductions in BP, no significant differences were found between the two devices. Thus, this study indicates the IB device to be an effective alternative to the ZON that can also be used to perform other IE modalities.

Effects of 6 Months of Exercise-Based Cardiac Rehabilitation on Autonomic Function and Neuro-Cardiovascular Stress Reactivity in Coronary Artery Disease Patients.

Background Autonomic dysregulation represents a hallmark of coronary artery disease (CAD). Therefore, we investigated the effects of exercise-based cardiac rehabilitation (CR) on autonomic function and neuro-cardiovascular stress reactivity in CAD patients. Methods and Results Twenty-two CAD patients (4 women; 62±8 years) were studied before and following 6 months of aerobic- and resistance-training-based CR. Twenty-two similarly aged, healthy individuals (CTRL; 7 women; 62±11 years) served as controls. We measured blood pressure, muscle sympathetic nerve activity, heart rate, heart rate variability (linear and nonlinear), and cardiovagal (sequence method) and sympathetic (linear relationship between burst incidence and diastolic blood pressure) baroreflex sensitivity during supine rest. Furthermore, neuro-cardiovascular reactivity during short-duration static handgrip (20s) at 40% maximal effort was evaluated. Six months of CR lowered resting blood pressure (P<0.05), as well as muscle sympathetic nerve activity burst frequency (48±8 to 39±11 bursts/min; P<0.001) and burst incidence (81±7 to 66±17 bursts/100 heartbeats; P<0.001), to levels that matched CTRL and improved sympathetic baroreflex sensitivity in CAD patients (P<0.01). Heart rate variability (all P>0.05) and cardiovagal baroreflex sensitivity (P=0.11) were unchanged following CR, yet values were not different pre-CR from CTRL (all P>0.05). Furthermore, before CR, CAD patients displayed greater blood pressure and muscle sympathetic nerve activity reactivity to static handgrip versus CTRL (all P<0.05); yet, responses were reduced following CR (all P<0.05) to levels observed in CTRL. Conclusions Six months of exercise-based CR was associated with marked improvement in baseline autonomic function and neuro-cardiovascular stress reactivity in CAD patients, which may play a role in the reduced cardiac risk and improved survival observed in patients following exercise training.

The Impact of Blood Pressure Dipping Status on Cognition, Mobility, and Cardiovascular Health in Older Adults Following an Exercise Program.

Objectives: To determine whether a dual-task gait and aerobic exercise intervention differentially impacted older adults with normal blood pressure (BP) dipping status (dippers) compared to those with nondipping status (nondippers). Methods: This study was a secondary analysis involving participants (mean age = 70.3 years, 61% women) who attended a laboratory-based exercise intervention over a 6-month period (40 min/day and 3 days/week). Participants were assessed in measures of cognition, mobility, and cardiovascular health at baseline, 3, 6, and 12 months (after a 6-month no-contact follow-up). Results: We observed improvements in cognition in both groups at 6 and 12 months, although no between-group differences were seen. Nondippers demonstrated superior improvements in usual gait velocity and step length after the exercise intervention compared to dippers. Dippers reduced daytime systolic BP at 6 and 12 months to a greater extent than nondippers. Discussion: BP dipping status at baseline did not influence exercise benefits to cognition but did mediate changes in mobility and cardiovascular health.

Acute Response to a 2-Minute Isometric Exercise Test Predicts the Blood Pressure-Lowering Efficacy of Isometric Resistance Training in Young Adults.

BACKGROUND: This work aimed to explore whether different forms of a simple isometric exercise test could be used to predict the blood pressure (BP)-lowering efficacy of different types of isometric resistance training (IRT) in healthy young adults. In light of the emphasis on primary prevention of hypertension, identifying those with normal BP who will respond to IRT is important. Also, heightened BP reactivity increases hypertension risk, and as IRT reduces BP reactivity in patients with hypertension, it warrants further investigation in a healthy population. METHODS: Forty-six young men and women (24 ± 5 years; 116 ± 10/ 68 ± 8 mm Hg) were recruited from 2 study sites: Windsor, Canada (n = 26; 13 women), and Northampton, United Kingdom (n = 20; 10 women). Resting BP and BP reactivity to an isometric exercise test were assessed prior to and following 10 weeks of thrice weekly IRT. Canadian participants trained on a handgrip dynamometer (isometric handgrip, IHG), while participants in the UK trained on an isometric leg extension dynamometer (ILE). RESULTS: Men and women enrolled in both interventions demonstrated significant reductions in systolic BP (P < 0.001) and pulse pressure (P < 0.05). Additionally, test-induced systolic BP changes to IHG and ILE tests were associated with IHG and ILE training-induced reductions in systolic BP after 10 weeks of training, respectively (r = 0.58 and r = 0.77; for IHG and ILE; P < 0.05). CONCLUSIONS: The acute BP response to an isometric exercise test appears to be a viable tool to identify individuals who may respond to traditional IRT prescription.

Isometric Handgrip as an Adjunct for Blood Pressure Control: a Primer for Clinicians.

Considered a global health crisis by the World Health Organization, hypertension (HTN) is the leading risk factor for death and disability. The majority of treated patients do not attain evidence-based clinical targets, which increases the risk of potentially fatal complications. HTN is the most common chronic condition seen in primary care; thus, implementing therapies that lower and maintain BP to within-target ranges is of tremendous public health importance. Isometric handgrip (IHG) training is a simple intervention endorsed by the American Heart Association as a potential adjuvant BP-lowering treatment. With larger reductions noted in HTN patients, IHG training may be especially beneficial for those who (a) have difficulties continuing or increasing drug-based treatment; (b) are unable to attain BP control despite optimal treatment; (c) have pre-HTN or low-risk stage I mild HTN; and (d) wish to avoid medications or have less pill burden. IHG training is not routinely prescribed in clinical practice. To shift this paradigm, we focus on (1) the challenges of current HTN management strategies; (2) the effect of IHG training; (3) IHG prescription; (4) characterizing the population for whom it works best; (5) clinical relevance; and (6) important next steps to foster broader implementation by clinical practitioners.

Combined Dual-Task Gait Training and Aerobic Exercise to Improve Cognition, Mobility, and Vascular Health in Community-Dwelling Older Adults at Risk for Future Cognitive Decline1.

This 6-month experimental case series study investigated the effects of a dual-task gait training and aerobic exercise intervention on cognition, mobility, and cardiovascular health in community-dwelling older adults without dementia. Participants exercised 40 min/day, 3 days/week for 26 weeks on a Biodex GaitTrainer2 treadmill. Participants were assessed at baseline (V0), interim (V1: 12-weeks), intervention endpoint (V2: 26-weeks), and study endpoint (V3: 52-weeks). The study outcomes included: cognition [executive function (EF), processing speed, verbal fluency, and memory]; mobility: usual & dual-task gait (speed, step length, and stride time variability); and vascular health: ambulatory blood pressure, carotid arterial compliance, and intima-media thickness (cIMT). Fifty-six participants [age: 70(6) years; 61% female] were included in this study. Significant improvements following the exercise program (V2) were observed in cognition: EF (p = 0.002), processing speed (p < 0.001), verbal fluency [digit symbol coding (p < 0.001), phonemic verbal fluency (p < 0.001)], and memory [immediate recall (p < 0.001) and delayed recall (p < 0.001)]; mobility: usual & dual-task gait speed (p = 0.002 and p < 0.001, respectively) and step length (p = 0.001 and p = 0.003, respectively); and vascular health: cIMT (p = 0.002). No changes were seen in the remaining outcomes. In conclusion, 26 weeks of dual-task gait training and aerobic exercise improved performance on a number of cognitive outcomes, while increasing usual & dual-task gait speed and step length in a sample of older adults without dementia.

Isometric exercise training lowers resting blood pressure and improves local brachial artery flow-mediated dilation equally in men and women.

INTRODUCTION: Isometric resistance training has repeatedly shown to be an effective exercise modality in lowering resting blood pressure (BP), yet associated mechanisms and sex differences in the response to training remain unclear. Exploration into potential sex differences in the response to isometric resistance training is necessary, as it may allow for more optimal and sex-based exercise prescription, thereby maximizing the efficacy of the training intervention. PURPOSE: Therefore, we investigated, in normotensives, whether sex differences exist in the response to isometric handgrip (IHG) training. METHODS: Resting BP and endothelium-dependent vasodilation (brachial artery flow-mediated dilation; FMD) were assessed in 11 women (23 ± 4 years) and 9 men (21 ± 2 years) prior to and following 8 weeks of IHG training (four, 2-min unilateral contractions at 30 % of maximal voluntary contraction; 3 days per week). RESULTS: Main effects of time were observed (all P < 0.05), whereby IHG training reduced systolic BP (Δ 8 ± 6 mmHg), diastolic BP (Δ 2 ± 3 mmHg), mean arterial pressure (Δ 4 ± 3 mmHg), and pulse pressure (Δ 5 ± 7 mmHg), accompanied by increases in absolute (Δ 0.09 ± 0.15 mm) and relative (Δ 2.4 ± 4.1 %) brachial artery FMD; however, no significant sex differences were observed in the magnitude of post-training change in any variable assessed (all P > 0.05). CONCLUSION: IHG training effectively lowers resting BP and improves endothelium-dependent vasodilation in men and women, without significant sex differences in the magnitude of response.

When and how to recommend 'alternative approaches' in the management of high blood pressure.

Several nonpharmacologic therapies, such as sodium restriction and weight loss, have been promoted by hypertension guidelines based on the trial evidence supporting their capacity to lower blood pressure. However, many patients may not respond or be able to adhere to these nonpharmacologic treatments. Despite numerous formal diet and lifestyle recommendations, the prevalence of hypertension continues to grow worldwide. As such, additional approaches are needed to help combat this public health epidemic. In this review, we outline the evidence supporting the efficacy of a number of alternative approaches for blood pressure lowering. On the basis of the recommendations by a recent American Heart Association scientific statement, we also provide guidance on when and how to implement these methods in clinical practice. The available evidence supports several approaches, including Transcendental Meditation, device-guided slow breathing, and aerobic, resistance, and isometric exercises. Nonetheless, many questions remain, and future recommendations for using alternative approaches will need to be updated as new trials are published.

Evidence for the emergence of leg sympathetic vasoconstrictor tone with age in healthy women.

While muscle sympathetic nerve activity (MSNA) is elevated with advancing age, correlational evidence suggests that, in contrast to men, basal MSNA is not related to resting lower limb hemodynamics in women. However, limited data exists in women that have attempted to directly assess the degree of limb sympathetic vasoconstrictor tone, and whether it is altered with age. To address this issue, we measured changes in femoral artery vascular conductance (FVC) during an acute sympatho-inhibitory stimulus (-60 mm Hg neck suction, NS) in groups of healthy younger (n = 8, 23 ± 1 years) and older (n = 7, 66 ± 1 years) women. The percent change in FVC in response to NS was significantly augmented in the older (P = 0.006 vs. young) women. Although NS caused no significant change (3 ± 3%, P = 0.33) in FVC in the young women, there was a robust increase in FVC (21 ± 5%, P = 0.003) in the old women. Collectively, these findings provide evidence that in women, leg sympathetic vasoconstrictor tone emerges with age.

Sit, breathe, smile: effects of single and weekly seated Qigong on blood pressure and quality of life in long-term care.

Long-term care (LTC) facilities house individuals with diverse combinations of cognitive and physical impairments, and the practice of Seated Qigong eliminates common exercise barriers. This study hypothesized: 1) a single session would lower blood pressure (BP) and improve quality of life (QOL) in a generalized LTC population, and 2) these responses would be attenuated with chronic (weekly) Seated Qigong practice. Ten residents (6 female; 86 ± 7 years) participated in 1X/week Seated Qigong sessions for 10-weeks. BP and QOL were assessed pre- and post-session at baseline and following 5- and 10-weeks of Qigong. Systolic BP was significantly reduced immediately post-session after 10-weeks of Qigong (P = 0.03), yet unchanged at baseline and after 5-weeks (all P > 0.05). Diastolic BP and QOL remained unchanged (P > 0.05). A session of Seated Qigong elicits a hypotensive response with exposure, supporting the notion that repeated sessions may provide advantageous health benefits.

Evidence for the role of isometric exercise training in reducing blood pressure: potential mechanisms and future directions.

Hypertension, or the chronic elevation in resting arterial blood pressure (BP), is a significant risk factor for cardiovascular disease and estimated to affect ~1 billion adults worldwide. The goals of treatment are to lower BP through lifestyle modifications (smoking cessation, weight loss, exercise training, healthy eating and reduced sodium intake), and if not solely effective, the addition of antihypertensive medications. In particular, increased physical exercise and decreased sedentarism are important strategies in the prevention and management of hypertension. Current guidelines recommend both aerobic and dynamic resistance exercise training modalities to reduce BP. Mounting prospective evidence suggests that isometric exercise training in normotensive and hypertensive (medicated and non-medicated) cohorts of young and old participants may produce similar, if not greater, reductions in BP, with meta-analyses reporting mean reductions of between 10 and 13 mmHg systolic, and 6 and 8 mmHg diastolic. Isometric exercise training protocols typically consist of four sets of 2-min handgrip or leg contractions sustained at 20-50 % of maximal voluntary contraction, with each set separated by a rest period of 1-4 min. Training is usually completed three to five times per week for 4-10 weeks. Although the mechanisms responsible for these adaptations remain to be fully clarified, improvements in conduit and resistance vessel endothelium-dependent dilation, oxidative stress, and autonomic regulation of heart rate and BP have been reported. The clinical significance of isometric exercise training, as a time-efficient and effective training modality to reduce BP, warrants further study. This evidence-based review aims to summarize the current state of knowledge regarding the effects of isometric exercise training on resting BP.

Effects of isometric handgrip training dose on resting blood pressure and resistance vessel endothelial function in normotensive women.

Isometric handgrip (IHG) training lowers resting blood pressure (BP) in both hypertensives and normotensives, yet the effect of training dose on the magnitude of reduction and the mechanisms associated with the hypotensive response are elusive. We investigated, in normotensive women, the effects of two different doses of IHG training on resting BP, and explored improved resistance vessel endothelial function and heart rate variability (HRV) as potential mechanisms of BP reduction. Resting BP, HRV, and resistance vessel endothelial function (venous strain-gauge plethysmography with reactive hyperemia) were assessed in 32 women before and after 4 and 8 weeks of 3×/week (n = 12) or 5×/week (n = 11) IHG training (four, 2-min unilateral contractions at 30 % maximal voluntary contraction), or 0×/week control (n = 9). IHG training decreased systolic BP in the 3×/week (94 ± 6 to 91 ± 6 to 88 ± 5 mmHg, pre- to mid- to post-training; P < 0.01) and 5×/week (97 ± 11 to 90 ± 9 to 91 ± 9 mmHg, P < 0.01) groups, concomitant with increased forearm reactive hyperemic blood flow (26 ± 7 to 30 ± 8 to 36 ± 9 mL/min/100 mL tissue, P < 0.01; and 26 ± 7 to 29 ± 7 to 38 ± 13 mL/min/100 mL tissue, P < 0.01, respectively), yet both remained unchanged in the control group. No changes were observed in diastolic BP, mean arterial BP, or any indices of HRV in any group (all P > 0.05). In conclusion, IHG training lowers resting systolic BP and improves resistance vessel endothelial function independent of training dose in normotensive women.

Cardiovascular stress reactivity tasks successfully predict the hypotensive response of isometric handgrip training in hypertensives.

This study aimed to determine whether: (a) isometric handgrip (IHG) training lowers resting blood pressure (BP), (b) cardiovascular reactivity to a serial subtraction (SST), IHG (IHGT), and cold pressor (CPT) task predicts this hypotensive response, and (c) cardiovascular reactivity is attenuated posttraining. Resting BP and cardiovascular reactivity to a SST, IHGT, and CPT were measured in 24 hypertensives (51-74 years) before and after 10 weeks of IHG training (n = 12) or control (n = 12). IHG training lowered resting BP (Δ8/5 mmHg), whereby the decrease in systolic BP was correlated to pretraining systolic BP reactivity to the SST (r = -.85) and IHGT (r = -.79; all ps < .01), but not the CPT (r = .34; p > .01). Furthermore, following IHG training, systolic BP reactivity to the SST (Δ7 mmHg) and IHGT (Δ8 mmHg) was reduced (all ps < .01). The results offer promising implications for hypertensives and may provide a tool to identify IHG training responders.

Simvastatin reduces sympathetic outflow and augments endothelium-independent dilation in non-hyperlipidaemic primary hypertension.

OBJECTIVES: Previous reports, involving hypercholesterolaemic hypertensive subjects, that statins reduce muscle sympathetic nerve activity (MSNA) did not investigate potential neural sites of such sympathoinhibition or determine its consequences for endothelial function or insulin resistance. This study of hypertensive subjects with lower plasma cholesterol tested the hypotheses that lipophilic simvastatin would attenuate resting sympathoexcitation and augment baroreflex modulation of MSNA and heart rate (HR), flow-mediated vasodilation and insulin sensitivity. DESIGN: Prospective, randomised, double-blind, placebo-controlled crossover study. SETTING: Academic hospital-based study. PATIENTS: Fourteen non-hyperlipidaemic primary hypertensive subjects (10 men; overall mean±SD age 58±12 years). INTERVENTIONS: Four weeks of simvastatin (80 mg/day) or placebo. MAIN OUTCOME MEASURES: Resting blood pressure (BP), HR, MSNA, spontaneous arterial baroreflex MSNA and HR modulation, endothelium-dependent and endothelium-independent vasodilation, and the homoeostatic model assessment of insulin resistance (HOMA-IR). RESULTS: Simvastatin lowered MSNA burst frequency (from 32±12 to 25±9 bursts/min) and MSNA burst incidence (from 55±23% to 43±17%; all p<0.01) without affecting BP, HR, baroreflex modulation of either MSNA or HR, or HR variability (all p>0.05). Plasma glucose, insulin, HOMA-IR and endothelium-dependent vasodilation (all p>0.05) were unchanged, whereas endothelium-independent vasodilation increased (7.1±3.8% to 9.7±3.9%, n=13; p<0.01). The fall in MSNA was unrelated to the decrease in low-density lipoprotein cholesterol (r=0.41, p=0.14). CONCLUSIONS: These findings are consistent with the concept that, in non-hyperlipidaemic subjects with primary hypertension, simvastatin causes a cholesterol-independent reduction in an elevated central set-point for MSNA, without affecting arterial baroreflex modulation of either MSNA or HR. There may be less neurogenic constraint on endothelium-independent vasodilation as a consequence.

Sex and life expectancy.

BACKGROUND: A sexual dimorphism in human life expectancy has existed in almost every country for as long as records have been kept. Although human life expectancy has increased each year, females still live longer, on average, than males. Undoubtedly, the reasons for the sex gap in life expectancy are multifaceted, and it has been discussed from both sociological and biological perspectives. However, even if biological factors make up only a small percentage of the determinants of the sex difference in this phenomenon, parity in average life expectancy should not be anticipated. OBJECTIVE: The aim of this review is to highlight biological mechanisms that may underlie the sexual dimorphism in life expectancy. METHODS: Using PubMed, ISI Web of Knowledge, and Google Scholar, as well as cited and citing reference histories of articles through August 2012, English-language articles were identified, read, and synthesized into categories that could account for biological sex differences in human life expectancy. RESULTS: The examination of biological mechanisms accounting for the female-based advantage in human life expectancy has been an active area of inquiry; however, it is still difficult to prove the relative importance of any 1 factor. Nonetheless, biological differences between the sexes do exist and include differences in genetic and physiological factors such as progressive skewing of X chromosome inactivation, telomere attrition, mitochondrial inheritance, hormonal and cellular responses to stress, immune function, and metabolic substrate handling among others. These factors may account for at least a part of the female advantage in human life expectancy. CONCLUSIONS: Despite noted gaps in sex equality, higher body fat percentages and lower physical activity levels globally at all ages, a sex-based gap in life expectancy exists in nearly every country for which data exist. There are several biological mechanisms that may contribute to explaining why females live longer than men on average, but the complexity of the human life experience makes research examining the contribution of any single factor for the female advantage difficult. However, this information may still prove important to the development of strategies for healthy aging in both sexes.