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The purpose of this study was to examine short-term longitudinal relationships between handgrip strength (HGS) and cardiovascular disease (CVD) biomarkers in middle-aged to older adults living in rural areas (N = 138). The association between HGS and CVD biomarkers was examined at baseline, with HGS as a predictor of the annual change in biomarkers, and in a parallel fashion between the annual change in HGS and CVD biomarkers over an average of 2.8 follow-up years. The results showed HGS to cross-sectionally associate with waist circumference and diastolic blood pressure at baseline, but HGS at baseline was not found to predict the annual change in any biomarker. The annual increase in HGS was significantly associated with favorable changes in high-density lipoprotein cholesterol, triglycerides, and systolic/diastolic blood pressures; yet, these associations varied by the baseline levels of biomarkers. The present findings suggest that improved muscle strength with aging is related to favorable changes in CVD biomarkers.

Long sleep durations (≥540 min) are associated with poor cognitive performance in ageing adults, but the underlying cause is unclear. The aim of this study was to investigate the effect of extended sleep on cognitive performance and cerebral vascular function before and then after aerobic exercise. In all, 12 adults completed 6 nights of 8- (control) and 10+-h (sleep extension) time in bed in a randomised, crossover experiment. Sleep was measured using wrist actigraphy. On the last day of each time in bed protocol, participants performed three bouts of brisk walking. Sustained attention, spatial rotation ability, mental flexibility, and working memory were assessed, while prefrontal oxygen saturation index (ΔTSI) was measured using near-infrared spectroscopy. A two-way repeated-measures analysis of variance (time in bed × before/after exercise) was used for statistical analysis. Average sleep duration was longer following sleep extension as compared to control, at a mean (SD) of 551 (16) versus 428 (20) min (p lt; 0.001). Sleep extension did not alter cognitive performance as compared to control, but increased ΔTSI during tests of spatial rotation ability (main effect for time in bed, p = 0.03), mental flexibility (p = 0.04), and working memory (p lt; 0.01). Cognitive performance was improved (main effect for exercise, p lt; 0.05) following brisk walking for all cognitive domains except sustained attention with no interaction with time in bed. In summary, 6 nights of extended time in bed accompanied by long sleep durations does not impair cognitive performance at rest or alter the positive effect of acute aerobic exercise on cognition but may increase frontal cerebral oxygenation during cognitive functioning.

Background A very limited amount of research has examined intermittent fasting (IF) programs, such as time-restricted feeding (TRF), in active populations. Objective Our objective was to examine the effects of TRF, with or without β-hydroxy β-methylbutyrate (HMB) supplementation, during resistance training (RT). Methods This study employed a randomized, placebo-controlled, reduced factorial design and was double-blind with respect to supplementation in TRF groups. Resistance-trained females were randomly assigned to a control diet (CD), TRF, or TRF plus 3 g/d HMB (TRFHMB). TRF groups consumed all calories between 1200 h and 2000 h, whereas the CD group ate regularly from breakfast until the end of the day. All groups completed 8 wk of supervised RT and consumed supplemental whey protein. Body composition, muscular performance, dietary intake, physical activity, and physiological variables were assessed. Data were analyzed prior to unblinding using mixed models and both intention-to-treat (ITT) and per protocol (PP) frameworks. Results Forty participants were included in ITT, and 24 were included in PP. Energy and protein intake (1.6 g/kg/d) did not differ between groups despite different feeding durations (TRF and TRFHMB: ∼7.5 h/d; CD: ∼13 h/d). Comparable fat-free mass (FFM) accretion (+2% to 3% relative to baseline) and skeletal muscle hypertrophy occurred in all groups. Differential effects on fat mass (CD: +2%; TRF: -2% to -4%; TRFHMB: -4% to -7%) were statistically significant in the PP analysis, but not ITT. Muscular performance improved without differences between groups. No changes in physiological variables occurred in any group, and minimal side effects were reported. Conclusions IF, in the form of TRF, did not attenuate RT adaptations in resistance-trained females. Similar FFM accretion, skeletal muscle hypertrophy, and muscular performance improvements can be achieved with dramatically different feeding programs that contain similar energy and protein content during RT. Supplemental HMB during fasting periods of TRF did not definitively improve outcomes. This study was prospectively registered at clinicaltrials.gov as NCT03404271.

BACKGROUND Declines in muscle morphology and function are commonly reported as a consequence of aging. However, few studies have investigated the influence of age on a comprehensive set of muscle function-related measures (i.e., reactive strength, power, etc.) that focuses on a dynamic performance task such as the vertical jump across the adult life span. This study aimed to examine the effects of age on muscle morphology characteristics (muscle cross-sectional area [CSA] and echo intensity [EI]) and vertical jump height, power, and reactive strength index (RSI) in females. METHODS Twenty-six young (22±2 years), 30 middle-aged (36±5 years), and 23 older (71±5 years) females participated in this study. Muscle CSA and EI were determined from ultrasound scans of the vastus lateralis. Countermovement jumps were used to assess jump height, RSI, movement time, and peak power (Pmax). RESULTS Muscle CSA, jump height, and Pmax were higher for the young compared to the old and middle-aged (P≤0.027) and for the middle-aged compared to the old (P

The purpose of this study was to determine whether L‐citrulline (CIT) supplementation during the follicular and luteal phases of the menstrual cycle would present differential effects on vasodilator kinetics in dynamically contracting muscle. Twenty‐four women were studied during the follicular (day 15 after onset of menses, n = 13) or the luteal phase (day 25 after onset of menses, n = 11). Supplementation with CIT (6g/day) or placebo occurred 7‐days prior to testing in a crossover design across two menstrual cycles. Forearm vascular conductance (FVC) was calculated from blood flow and mean arterial pressure measured continuously during handgrip exercise performed at 10% maximal grip strength. FVC was calculated for each duty cycle (contract:relax, 1:2s) and expressed as a change from baseline (ΔFVC) before being fit with a monoexponential model. Amplitude of the ΔFVC response and the number of duty cycles for ΔFVC to reach 63% of steady‐state amplitude (τΔFVC) were derived from the model. Analysis of variance showed no difference in the amplitude of ΔFVC between CIT and placebo (p = .45) or between menstrual cycle phases (p = .11). Additionally, τΔFVC was not different (p = .35) between CIT and placebo in women tested during the follicular (6 ± 3 versus 5 ± 3 duty cycles) or luteal phase (9 ± 1 versus 8 ± 1 duty cycles) although τΔFVC was found to be slower for women tested during the luteal as compared to the follicular phase (8 ± 4 versus 5 ± 3 duty cycles, p = .02). These results indicate that exercise‐onset vasodilator kinetics is unaltered with CIT supplementation in young healthy women irrespective of menstrual cycle phase., Exercise‐onset vasodilator kinetics was unaltered with L‐citrulline supplementation in young women tested during the follicular and luteal phase indicating that fluctuations in estrogen and progesterone do not influence the ability of L‐citrulline to enhance substrate availability for nitric oxide production. Vasodilator kinetics were faster during the follicular than luteal phase consistent with the notion that peripheral vascular reactivity may vary across the menstrual cycle.

Age-associated reduction in endothelial nitric oxide (NO) synthesis contributes to the development of cardiovascular diseases and sarcopenia. L-Citrulline is a precursor of NO with the ability to improve vascular function and muscle protein synthesis. We hypothesize that vascular and muscular benefits associated with oral L-citrulline supplementation might be augmented by concomitant supplementation with exercise training in older adults.

OBJECTIVE The menopausal transition has a negative effect on peripheral dilation in response to various stimuli including shear stress and exercise. Whether the presence of elevated traditional cardiovascular disease (CVD) risk factors in women going through menopause exacerbates the adverse effect on peripheral vasodilation is unclear. METHODS Forty-four perimenopausal women with relatively low CVD risk were divided into tertiles based on atherosclerotic CVD (ASCVD) 10-year risk scores (lowest: 0.1%-0.5%, middle: 0.6%-0.9%, higher: >1%). Comparisons were made across tertile groups for the femoral artery vascular conductance (FVC) response to single-leg knee extension exercise (0, 5, 10, 15 W) as measured using Doppler ultrasound. RESULTS At higher exercise intensities, FVC was lower in women in the tertile group with the highest ASCVD 10-year risk scores (10 W: 6 ± 2 mL/min/mm Hg, 15 W: 8 ± 3 mL/min/mm Hg) compared to women in the lowest tertile group (10 W: 9 ± 3 mL/min/mm Hg, P = 0.01; 15 W: 12 ± 3 mL/min/mm Hg, P

Supplementation with l-citrulline (Cit) has been shown to improve muscle oxygenation and oxygen uptake kinetics during moderate- to high-intensity cycling in young men. The aim of this study was to test the hypothesis that Cit would improve oxygen uptake kinetics during walking in older and young adults. In a randomized, double-blind study, 26 (15 women, 11 men) adults between the ages of 20–35 years (n = 15) and 64–86 years (n = 11) completed 7-day periods of taking placebo and Cit (6 g/day) in a crossover manner. Participants walked on a treadmill at 40% heart rate reserve while pulmonary oxygen uptake was measured using indirect calorimetry. Net oxygen cost, mean response time (MRT), and the oxygen deficit were calculated before and after each supplement period. There was no significant change (P > 0.05) in net oxygen cost, MRT, or the oxygen deficit after Cit in older adults, while young adults showed a decrease (P = 0.05) in the oxygen deficit after Cit that tended (P = 0.053) to be different than the change after placebo. Sex-stratified analysis revealed that Cit decreased MRT (P = 0.04, Cohen’s d = 0.41) and the oxygen deficit (P < 0.01, Cohen’s d = 0.56) in men with the change after Cit being greater than the change after placebo (MRT: −4.5 ± 2.1 vs. 3.4 ± 2.1 s, P = 0.01; deficit: −0.15 ± 0.05 vs. 0.01 ± 0.05 L, P = 0.02). All oxygen uptake parameters were unchanged (P > 0.05) following Cit and placebo in women. Cit does not alter the oxygen cost of moderate-intensity walking in young or older adults, but Cit improved the rate of rise in oxygen uptake at exercise onset in men.

To date, few studies have analyzed the effects of exercise on cardiac adipose tissue. Overall, exercise programs did not meet the recommendations for significant weight loss, the utilization of resistance training was minimal, and the conclusions derived from these studies have diminished exercise as a strategy for cardiac fat loss. The objective of this pilot study was to analyze the effects of 3-week high-intensity, moderate-volume muscular endurance resistance training (RT) on cardiac fat and arterial stiffness. A total of 11 young females with obesity, BMI = 34.13 (± 3.16) kg/m2 (n = 5 control, n = 6 intervention) completed the study. Absolute strength was assessed using one repetition maximum test (1RM) for bench press (BP) and leg press (LP), and relative strength was calculated using body weight (BW) as BP-to-BW and LP-to-BW ratio. Magnetic resonance was used to quantify epicardial and paracardial adipose tissue (EAT and PAT) volume, and applanation tonometry was used to assess arterial stiffness by estimating pulse wave velocity (PWV). EAT and PAT volumes (ml) showed significant interaction effects (p = 0.037 and p = 0.031), and very large changes (d > 1) of EAT (p = 0.006) and PAT (p = 0.036) in the intervention group. In addition, strength was significantly improved, including BP (p = 0.003), LP (p = 0.001), BP-to-BW ratio (p = 0.001), and LP-to-BW ratio (p = 0.002), while no changes were found in PWV. High-intensity, moderate-volume RT, designed to enhance muscular endurance following the recommendations reduces EAT and PAT volumes, improves physical fitness in females with obesity, and has no negative effects on arterial stiffness.

What is the central question of this study? Does short-term supplementation with l-citrulline in order to increase l-arginine improve exercise blood flow and peripheral dilatation responses to exercise in older adults? What is the main finding and its importance? l-Citrulline increased femoral blood flow by 11% and vascular conductance by 14% during lower-limb exercise in older men, whereas no changes were observed in older women. This modest improvement in bulk muscle blood flow in older men has implications for altering muscle metabolism that may result in enhanced exercise tolerance in older adults. l-Citrulline (Cit) increases l-arginine (Arg), the primary substrate for nitric oxide biosynthesis. We tested the hypothesis that muscle blood flow during exercise would be enhanced by Cit supplementation in older adults. Femoral artery blood flow was measured during calf exercise using Doppler ultrasound, and vascular conductance (FVC) was calculated in 25 older adults (13 women and 12 men) before and after 14 days of Cit (6 g day-1 ) and placebo (maltodextrin) in a randomized, double-blind, crossover study. Plasma [Arg] and resting blood pressure were also measured before and after each condition. Women and men were analysed separately because of significant sex-by-condition interactions for the change in exercise blood flow and FVC. Plasma [Arg] was increased by 30 and 35% after Cit (P < 0.01) in women and men, respectively, with no change after placebo. Citrulline lowered diastolic blood pressure in men (75 ± 9 versus 71 ± 6 mmHg, P = 0.02), but this variable remained unchanged in women. Blood flow and FVC during exercise at higher workloads were increased after Cit in men (flow, 521 ± 134 versus 584 ± 166 ml min-1 , P = 0.04; FVC, 5.0 ± 1.5 versus 5.8 ± 1.7 m, min mmHg-1 , P = 0.01) but were not different after placebo. These variables were not altered by Cit in women. Adjusting for baseline diastolic blood pressure removed (P = 0.10) the difference in FBF and FVC following Cit in men. These results indicate that l-citrulline has a modest effect of improving muscle blood flow during submaximal exercise in older men.

Central arterial hemodynamics is associated with cognitive impairment. Reductions in gait speed during walking while performing concurrent tasks known as dual-tasking (DT) or multi-tasking (MT) is thought to reflect the cognitive cost that exceeds neural capacity to share resources. We hypothesized that central vascular function would associate with decrements in gait speed during DT or MT.Gait speed was measured using a motion capture system in 56 women (30-80y) without mild-cognitive impairment. Dual-tasking was considered walking at a fast-pace while balancing a tray. Multi-tasking was the DT condition plus subtracting by serial 7's. Applanation tonometry was used for measurement of aortic stiffness and central pulse pressure. Doppler-ultrasound was used to measure blood flow velocity and β-stiffness index in the common carotid artery.The percent change in gait speed was larger for MT than DT (14.1±11.2 vs. 8.7±9.6%, p0.01). Tertiles were formed based on the percent change in gait speed for each condition. No vascular parameters differed across tertiles for DT. In contrast, carotid flow pulsatility (1.85±0.43 vs. 1.47±0.42, p=0.02) and resistance (0.75±0.07 vs. 0.68±0.07, p=0.01) indices were higher in women with more decrement (third tertile) as compared to women with less decrement (first tertile) in gait speed during MT after adjusting for age, gait speed, and task error. Carotid pulse pressure and β-stiffness did not contribute to these tertile differences.Elevated carotid flow pulsatility and resistance are characteristics found in healthy women that show lower cognitive capacity to walk and perform multiple concurrent tasks.

Aim Cognitive dysfunction is associated with slower gait speed in older women, but whether cognitive function affects gait performance earlier in life has yet to be investigated. Thus, the objective of this study was to test the hypothesis that cognitive function will discriminate gait performance in healthy younger women. Methods Fast-pace and dual-task gait speed were measured in 30 young to middle-aged (30–45 y) and 26 older (61–80 y) women without mild cognitive impairment. Visuoperceptual ability, working memory, executive function, and learning ability were assessed using neuropsychological tests. Within each age group, women were divided by the median into lower and higher cognitive function groups to compare gait performance. Results Younger women with higher visuoperceptual ability had faster fast-pace (2.25 ± 0.30 vs. 1.98 ± 0.18 m/s, p ≤ 0.01) and dual-task gait speed (2.02 ± 0.27 vs. 1.69 ± 0.25 m/s, p ≤ 0.01) than women with lower visuoperceptual ability. The difference in dual-task gait speed remained significant (p = 0.02) after adjusting for age, years of education, and other covariates. Dividing younger women based on other cognitive domains showed no difference in gait performance. In contrast, working memory and executive function discriminated dual-task gait speed (p Conclusion To our knowledge, this is the first study to show that poorer cognitive function even at a relatively young age can negatively impact mobility. Different cognitive functions discriminated gait performance based on age, highlighting a possible influence of aging in the relationship between cognitive function and mobility in women.

Central aortic blood pressure (BP) is reduced after exercise. The aim of this study was to determine whether cardiorespiratory fitness relates to postexercise reductions in aortic BP.Sixteen young adults completed maximal exercise testing for peak oxygen uptake (VO2). Participants walked at a slow (80 steps/min, ~47% maxHR) and fast (125 steps/min, ~65% maxHR) stepping cadence for 3000 steps on two nonconsecutive days. Before and after each walking condition, radial tonometry was used to derive aortic pressures. Measurements after walking were taken after 30 and 60 min of supine recovery.The change in aortic BP was similar between walking cadences. Aortic systolic BP (-2.3 mmHg, P=0.03) and pulse pressure (-3.2 mmHg, P0.001) were significantly reduced after 60 min of recovery as compared to baseline. The reduction in aortic pulse pressure was associated with decreased forward (r=0.69, P0.001) and backward wave pressure (r=0.70, P0.001). Peak VO2 was not associated (P0.05) with these changes, but was strongly associated with non-significant changes in aortic systolic BP (30min: r=-0.54, P=0.03) and diastolic BP (30 min: r=-0.64, 60 min: r=-0.77; both P0.01) after slow walking only.These results indicate that cardiorespiratory fitness associates with aortic pressure reductions after walking dependent on exercise intensity.

We aimed to test the hypothesis that central blood pressure (BP) would be lower in healthy older adults with greater daily ambulatory activity. Forty-three (24 women, 19 men) older adults wore a triaxial accelerometer at the hip for 1 week. The volume of ambulatory activity was estimated by average steps per day. As a proxy of intensity of ambulatory activity, 1-min peak step accumulation, or the maximum number of steps taken within a minute was averaged from each day. Participants were considered “active” if they had >7500 steps per day or >105 steps per min. Radial arterial tonometry was used to estimate central (aortic) BP from pulse wave analysis. After adjusting for age and sex, adults with higher steps per day (n = 18) tended to have lower central pulse pressure (p = 0.08). Interestingly, adults with higher peak step accumulation (n = 25) had significantly lower central pulse pressure (40.4 ± 1.6 vs. 46.8 ± 2.0 mmHg; p = 0.02) after adjusting for age and sex. Stepwise regression including age, sex, body mass index, and peak step accumulation found body mass index to be the strongest predictor of central systolic BP [β = 0.42, 95 % CI (0.13, 0.70), p = 0.004] while peak step accumulation was the strongest predictor of central pulse pressure [β = −0.31, 95 % CI (−0.01, −0.60), p = 0.043]. These results find older adults with an “active” daily walking pattern, particularly having a higher number of maximal steps in a minute, have lower central pulse pressure than older adults with lower daily ambulatory activity.

L-citrulline (Cit) increases arginine (Arg), the primary substrate for nitric oxide biosynthesis. We tested the hypothesis that muscle blood flow during exercise would be enhanced by Cit supplementation in older adults. Femoral artery blood flow was measured during calf exercise using Doppler ultrasound, and vascular conductance (FVC) was calculated in 25 older adults (13W, 12M) before and after 14 days of Cit (6 g/day) and placebo (maltodextrin) in a randomized, double-blind, crossover study. Plasma [Arg] and resting blood pressure were also measured before and after each condition. Women and men were analyzed separately due to significant sex-by-condition interactions for the change in exercise blood flow and FVC. Plasma [Arg] was increased by 30% and 35% following Cit (P < 0.01) in women and men, respectively, with no change after placebo. Citrulline lowered diastolic blood pressure in men (75 ± 9 vs. 71 ± 6 mmHg, P = 0.02), but remained unchanged in women. Blood flow and FVC during exercise at higher workloads were increased following Cit in men (flow: 521 ± 134 vs. 584 ± 166 mL/min, P = 0.04; FVC: 5.0 ± 1.5 vs. 5.8 ± 1.7 mL/min/mmHg, P = 0.01) but was not different after placebo. These variables were not altered by Cit in women. Adjusting for baseline diastolic blood pressure removed (P = 0.10) the difference in FBF and FVC following Cit men. These results indicate that L-citrulline has a modest effect of improving muscle blood flow during submaximal exercise in older men.

To test the hypothesis that volume or intensity of daily ambulatory activity would associate with greater large artery compliance in healthy untrained adults.Cross-sectional study.Forty-five recreationally active young adults (22 ± 3 yr, 51% women) wore an accelerometer for 5.3 ± 1.3 days for determination of average daily steps (volume) and 30-min peak stepping cadence (intensity; average steps per min for the 30 highest min in a day). Arterial compliance of the common carotid artery, superficial femoral artery (SFA), and popliteal artery was estimated using Doppler ultrasound. Data were analyzed using correlational analysis and analysis of covariance.Average daily steps and peak stepping cadence was 8957 ± 3422 steps per day and 97 ± 24 steps per min, respectively. Weight was the main independent predictor of daily steps (r(2) = 0.13, p = 0.01) and peak stepping cadence (r(2) = 0.17, p0.01). After adjusting ambulatory activity for weight, SFA compliance was positively correlated with peak stepping cadence (r = 0.53, p0.01) but not with daily steps (r = 0.23, p0.05). No other correlations were found between ambulatory activity and carotid or popliteal artery compliance (p0.05). Adults with peak stepping cadence ≥ 102 steps per min had greater carotid (1.26 ± 0.08 vs. 1.57 ± 0.09 mm(2) kPa(-1); p = 0.01) and SFA compliance (0.43 ± 0.03 vs. 0.54 ± 0.03 mm(2) kPa(-1); p = 0.04) than adults with lower stepping cadence."Brisk" stepping cadence during daily ambulation is associated with greater leg vascular compliance. These results support the promotion of accumulating 30 min of "brisk" walking per day as a strategy to improve vascular health.

Task-related brain activity is associated with preferred pace gait speed in older adults. Whether similar regional brain activity relates to fast pace gait speed has yet to be determined, but may provide insight into neural substrate important for walking under various conditions. This study measured regional blood-oxygen-level dependent (BOLD) changes using functional magnetic resonance imaging (fMRI) in response to a spatial Simon/Stroop task in community-dwelling older adults (N = 20, 63-80y). Preferred pace, fast pace, and dual-task gait speeds (picking up objects at preferred pace; fast walking over obstacles) were measured across a 7-meter course. Time to complete a fast pace 400 m walk test was also recorded. Partial correlations were used for all analyses after adjusting for age. Accuracy on incongruent trials of the spatial task was positively correlated with all fast walking conditions (all p 0.01), but not preferred pace walking conditions. BOLD signal change in the left middle frontal gyrus during the spatial task was associated with preferred pace gait speed (r = 0.51, p = 0.02) and fast walking over obstacles (r = 0.53, p = 0.01). Interestingly, BOLD signal change in the bilateral precuneus was associated with fast pace gait speed (r = 0.58, p 0.01), fast walking over obstacles (r = 0.48, p = 0.03), and 400 m walk time (r=-0.49, p = 0.02). These results find preferred and fast pace gait speed are associated with different regional task-related brain activity, with activation in the precuneus related with greater performance during fast pace walking.

Declines in endothelial function can take place rapidly across the menopause transition, placing women at heightened risk for atherosclerosis. Disturbed patterns of conduit artery shear, characterized by greater oscillatory and retrograde shear, are associated with endothelial dysfunction but have yet to be described across menopause. Healthy women, who were not on hormone therapy or contraceptives, were classified into early perimenopausal, late perimenopausal, and early postmenopausal stage. Resting antegrade, retrograde, and oscillatory shear were calculated from blood velocity and diameter measured in the brachial and common femoral artery using Doppler ultrasound. Serum was collected for measurements of estradiol, follicle‐stimulating hormone (FSH), and luteinizing hormone. After adjusting for age, brachial artery oscillatory shear was significantly higher in early postmenopausal women (n = 15, 0.17 ± 0.08 a.u.) than both early (n = 12, 0.08 ± 0.05 a.u., P

L-Citrulline, either synthetic or in watermelon, may improve vascular function through increased L-arginine bioavailability and nitric oxide synthesis. This article analyses potential vascular benefits of L-citrulline and watermelon supplementation at rest and during exercise.There is clear evidence that acute L-citrulline ingestion increases plasma L-arginine, the substrate for endothelial nitric oxide synthesis. However, the subsequent acute improvement in nitric oxide production and mediated vasodilation is inconsistent, which likely explains the inability of acute L-citrulline or watermelon to improve exercise tolerance. Recent studies have shown that chronic L-citrulline supplementation increases nitric oxide synthesis, decreases blood pressure, and may increase peripheral blood flow. These changes are paralleled by improvements in skeletal muscle oxygenation and performance during endurance exercise. The antihypertensive effect of L-citrulline/watermelon supplementation is evident in adults with prehypertension or hypertension, but not in normotensives. However, L-citrulline supplementation may attenuate the blood pressure response to exercise in normotensive men.The beneficial vascular effects of L-citrulline/watermelon supplementation may stem from improvements in the L-arginine/nitric oxide pathway. Reductions in resting blood pressure with L-citrulline/watermelon supplementation may have major implications for individuals with prehypertension and hypertension. L-Citrulline supplementation, but not acute ingestion, have shown to improve exercise performance in young healthy adults.

Subendocardial viability ratio (SEVR) is a measure of left ventricular function, specifically; it is an index of myocardial perfusion relative to left ventricular workload. Women have lower SEVR than men, partly due to a faster resting heart rate that reduces diastolic time (i.e., time for myocardial perfusion). It is unclear if body fat relates to SEVR, thus the purpose of this study was to examine the relation between body fat and SEVR in women. Twenty-eight middle-aged (31-45 years) and 31 older (60-80 years) women were examined. Radial artery applanation tonometry was used to calculate SEVR from a synthesized central aortic pressure wave. Dual-energy X-ray absorptiometry was used to assess body composition including fat in the trunk, legs, android and gynoid regions. Body fat was not related (P>.05) with SEVR in older women. In middle-aged women, all measures of regional fat were correlated with heart rate (range, r=.49-.59, P≤.01) and SEVR (range, r=.43-.53, P≤.01). Android-to-gynoid ratio was identified as the strongest predictor (r(2) =-.26, P

The aim of the present study was to determine if leg function is associated with ventilatory efficiency during exercise in healthy older adults. 24 women and 18 men aged 60–80 years performed treadmill exercise to fatigue for calculation of ventilatory efficiency using the ratio of ventilation to carbon dioxide at the anaerobic threshold (VE/VCO2@AT). On a separate day, participants performed leg strength testing and graded single-leg knee extension exercise. The VE/VCO2@ AT was higher in women than men (33 ± 3 vs. 30 ± 3; p = 0.03). After adjustment for age and VO2max, leg strength (knee extensor isometric force) was inversely associated with VE/VCO2@ AT in women (r = −0.44, p = 0.03) while no relationships were found for men. Strength-matched women and men had similar VE/VCO2@AT indicating that the correlation between leg strength and VE/VCO2@AT was strength-but not sex-specific. During knee extensor exercise, women with lower leg strength had increased VE/VCO2 slope across 0–15 W as compared to higher strength women (38 ± 8 vs. 31 ± 3; p < 0.05), while no differences were found for men. These results find leg strength to be associated with ventilatory responses to exercise in healthy older women, a finding that might be related to lower leg strength in women than men.

The authors examined interindividual and sex-specific variation in systolic (SBP) and diastolic (DBP) blood pressure responses to graded leg-extension exercise in healthy older (60–78 yr) women (n = 21) and men (n = 19). Maximal oxygen uptake (VO2max), body composition, physical activity (accelerometry), and vascular function were measured to identify predictors of exercise BP. Neither VO2max nor activity counts were associated with the rise in SBP or DBP during exercise in men. The strongest predictors of these responses in men were age (SBP: r2 = .19, p = .05) and peak exercise leg vasodilation (DBP: r2 = –.21, p < .05). In women, the modest relationship observed between VO2max and exercise BP was abolished after adjusting for central adiposity and activity counts (best predictors, cumulative r2 = .53, p < .05, for both SBP and DBP). These results suggest that determinants of variation in submaximal exercise BP responses among older adults are sex specific, with daily physical activity influencing these responses in women but not men.

Shear stress is the frictional force of blood against the endothelium, a stimulus for endothelial activation and the release of von Willebrand factor (vWF). This study tested the hypothesis that the increase in shear stress associated with exercise correlates with plasma vWF. Young (n = 14, 25.7 +/- 5.4 years) and older (n = 13, 65.6 +/- 10.7 years) individuals participated in 30 min of dynamic handgrip exercise at a moderate intensity. Brachial artery diameter and blood flow were measured using ultrasound Doppler and blood samples were collected before, immediately after, and following 30 min of recovery from exercise with plasma levels of vWF. Plasma levels of vWF increased (P0.05) by 6 +/- 2% in young individuals and 4 +/- 1% in older individuals immediately after exercise. The change in plasma vWF was linearly correlated with the increase in shear stress during exercise in older individuals (post-exercise: r = 0.78, 30 min recovery: r = 0.77, P0.01), but no association was found in the young individuals. These changes in plasma levels of vWF in humans suggest that aging influences endothelial activation and hemostasis.

Shear stress is considered an important stimulus for vascular adaptations with exercise training, yet the shear rate response to exercise has not been carefully examined in women or in healthy older adults. Therefore, the purpose of this study was to determine if age or sex differences are present in common femoral artery (CFA) shear rates during leg exercise. Diameter and mean blood velocity were measured in the CFA using Doppler ultrasound in young (20-30 yr) and older (60-79 yr) men and women at rest and during single-leg knee extensor exercise. Shear rate was calculated. Resting shear rate was lower in older compared to young adults (33.9 ± 3. 7v s. 58.3 ± 3. 6s −1 , respectively; p< 0.05) and lower in men than women (36.8 ± 3. 8v s. 55.4 ± 3. 5s −1 , respectively; p< 0.05). During exercise, older adults had overall lower shear rates compared to young adults (within-sex comparison, p< 0.05). The rise in shear rate with work rate showed no age difference but was lower in men than women (4.6 ± 0. 4v s. 8.6 ± 0. 4s −1 per W, p< 0.05). These results suggest that age and sex differences are present in CFA shear rates during exercise which could have implications for vascular adaptability with exercise training.

The aim of this study was to test the hypothesis that prior heavy exercise results in a higher oxygen cost during a subsequent bout of moderate exercise due to changes in muscle activity. Eight male subjects (25+/-2 yr, +/-SE) performed moderate-moderate and moderate-heavy-moderate transitions in work rate (cycling intensity, moderate=90% LT, heavy=80% VO(2) peak). The second bout of moderate exercise was performed after 6 min (C) or 30s (D) of recovery. Pulmonary gas exchange was measured breath-by-breath and surface electromyography was obtained from the vastus lateralis and medialis muscles. Root mean square (RMS) and median power frequency (MDPF) were computed. Prior heavy exercise increased DeltaVO(2)/DeltaWR (C: +2.0+/-0.8 ml min(-1)W(-1), D: +3.4+/-0.8 ml min(-1)W(-1); P0.05) and decreased exercise efficiency (C: -13.3+/-5.6%, D: -22.2 +/-4.9%; P0.05) during the second bout of moderate exercise in the absence of changes in RMS. MDPF was slightly elevated ( approximately 2%) during the second bout of moderate exercise, but MDPF was not correlated with V O(2) (r=0.17). These findings suggest that the increased oxygen cost during moderate exercise following heavy exercise is not due to increased muscle activity as assessed by surface electromyography.

To test the hypothesis that sex influences forearm blood flow (FBF) during exercise, 15 women and 16 men of similar age [women 24.3 ± 4.0 (SD) vs. men 24.9 ± 4.5 yr] but different forearm muscle strength (women 290.7 ± 44.4 vs. men 509.6 ± 97.8 N; P < 0.05) performed dynamic handgrip exercise as the same absolute workload was increased in a ramp function (0.25 W/min). Task failure was defined as the inability to maintain contraction rate. Blood pressure and FBF were measured on separate arms during exercise by auscultation and Doppler ultrasound, respectively. Muscle strength was positively correlated with endurance time ( r = 0.72, P < 0.01) such that women had a shorter time to task failure than men (450.5 ± 113.0 vs. 831.3 ± 272.9 s; P < 0.05). However, the percentage of maximal handgrip strength achieved at task failure was similar between sexes (14% maximum voluntary contraction). FBF was similar between women and men throughout exercise and at task failure (women 13.6 ± 5.3 vs. men 14.5 ± 4.9 ml·min−1·100 ml−1). Mean arterial pressure was lower in women at rest and during exercise; thus calculated forearm vascular conductance (FVC) was higher in women during exercise but similar between sexes at task failure (women 0.13 ± 0.05 vs. men 0.11 ± 0.04 ml·min−1·100 ml−1·mmHg−1). In conclusion, the similar FBF during exercise was achieved by a higher FVC in the presence of a lower MAP in women than men. Still, FBF remained coupled to work rate (and presumably metabolic demand) during exercise irrespective of sex.

This study examined the magnitude of the oxygen uptake slow component \((\dot{V}\hbox{O}_{2}\; \hbox{SC})\) during heavy exercise when preceded by heavy knee extension (KE) exercise. Nine males (26.6 ± 1.7 years, ±SE) performed repeated bouts of heavy exercise, each lasting 6 min with 6 min of recovery. Cycling–cycling trials (CYC1, CYC2) involved step transitions to a workrate corresponding to 50% of the difference between peak \(\dot{V}\hbox{O}_{2}\) and the lactate threshold (Δ 50%). During bilateral KE-cycling trails (KE, CYC3), KE was performed at an intensity requiring twofold greater muscle activation relative to CYC1 followed by a cycling transition to Δ 50%. \(\dot{V}\hbox{O}_{2}\) was measured breath-by-breath and was modeled using three exponentials to determinate the amplitudes (A2′, A3′) and time constants (τ2, τ3) of the primary phase and \(\dot{V}\hbox{O}_{2}\) SC. Electromyography (EMG) recorded from the vastus lateralis and medialis was averaged and reported relative to maximal voluntary contraction (%MVC). EMG was higher (p < 0.05) during KE (37.6 ± 8.1 %MVC) than CYC1 (20.8 ± 1.9 %MVC), CYC2 (21.6 ± 5.7 %MVC) and CYC3 (19.8 ± 6.3 %MVC). The amplitude of the \(\dot{V}\hbox{O}_{2}\) SC was lower (p < 0.05) in CYC2 (197 ± 120 ml min−1) and CYC3 (163 ± 51 ml min−1) compared to CYC1 (325 ± 126 ml min−1). No difference in \(\dot{V}\hbox{O}_{2}\) SC was observed between CYC2 and CYC3. Although the activation of additional motor units during KE exercise reduced the amplitude of the \(\dot{V}\hbox{O}_{2}\) SC, the decrease was similar to that observed following heavy cycling exercise. Thus, the activation of motor units in excess of those required for the activity does not alter the\(\dot{V}\hbox{O}_{2}\) response during a subsequent bout of exercise.

Previous studies have reported women to have a greater resistance to fatigue than men during sustained handgrip exercise, however, observed gender differences in fatigue has been shown to be a function of contraction type. The purpose of the present study was to determine if gender differences exist in forearm muscle fatigue during intermittent handgrip contractions. Women [n = 11, 23.5 ± 1.5 (SE) yr] and men (n = 11, 24.1 ± 1.5 yr) performed intermittent isometric handgrip contractions at a target force of 50% of maximal voluntary contraction (MVC) for 5 s followed by 5 s rest until task failure. Rate of fatigue was calculated from MVCs taken every 2 min during exercise, and recovery of muscle strength was measured in 5 min increments until 45 min post-task failure. Forearm muscle strength was less for women than men (W: 341.5 ± 11.9 N; M: 480.2 ± 28.0 N; p < 0.05). No gender difference was present in time to task failure (W: 793.3 ± 92.5 s; M: 684.8 ± 76.3 s) or in the decrease in muscle force generating capacity at task failure (W: -47.6 ± 1.0%; M: -49.9 ± 1.3%). Rate of muscle fatigue was found to be similar between women and men (W: -3.6 ± 0.5 %·min-1; M: -4.3 ± 0.6 %·min-1) and no gender difference was found in the recovery of muscle strength following task failure. In summary, no gender difference was found in the fatigability of the forearm muscles during intermittent submaximal handgrip contractions, independent of muscle strength

To determine if an echinacea-based dietary supplement (EBS) provided at two different doses (a regular dose (RD), 8,000 mg/day, vs. a double dose (DD), 16,000 mg/day) would increase erythropoietin (EPO) and other blood markers involved in improving aerobic capacity and maximal oxygen consumption (VO2max) in endurance-trained men. Secondly, to determine if any sex differences exist between male and female endurance-trained athletes.Forty-five endurance athletes completed three visits during a 35-day intervention. Participants were randomized into placebo (PLA; n = 8 men, n = 7 women), RD of EBS (n = 7 men, n = 8 women), or DD of EBS (n = 15 men) for the 35-day intervention period. At baseline, weight, body composition, and VO2max were measured. Blood was drawn to measure EPO, ferritin, red blood cells, white blood cells, hemoglobin, and hematocrit. At the mid-intervention visit, blood was collected. At the post-intervention visit, all measurements from the baseline visit were obtained once again.There was a significant increase in VO2max for endurance-trained men in PLA (increase of 2.8 ± 1.5 ml kg(-1) min(-1), p = .01) and RD of EBS (increase of 2.6 ± 1.8 ml kg(-1) min(-1), p = .04), but not in DD of EBS (p = .96). Importantly, there was no difference in the change in VO2max between PLA and RD of EBS. For endurance-trained women, VO2max did not change in either treatment (PLA: -0.7 ± 1.7 ml kg(-1) min(-1), p = .31; RD of EBS: -0.2 ± 2.4 ml kg(-1) min(-1), p = .80). There were no significant changes in any blood parameter across visits for any treatment group.This EBS should not be recommended as a means to improve performance in endurance athletes.

The aim of this study was to determine if stepping cadence when controlling for total steps has a differential impact on regional vascular function. 16 young adults (21±2 years) performed fast (125 steps per min) and slow (80 steps per min) walking for a total of 3 000 steps on separate days. Doppler ultrasound was used to measure compliance, blood flow and shear rate of the common carotid artery and superficial femoral artery before walking and at 30 and 60 min after walking. Carotid compliance was significantly (p

We investigated whether central and/or peripheral arterial stiffness contributes to increased perceived fatigue during walking in mobility-intact older adults. Arterial stiffness of the common carotid artery and superficial femoral artery (SFA) was measured using Doppler-ultrasound in 45 community-dwelling women and men (60-78yrs). The change in perceived fatigue was measured after a fast-pace 400meter walk test. Adults that rated feeling more tired after walking (n=10) had higher SFA stiffness (p

We tested the hypothesis that the intensity of daily ambulation would relate with functional walking capacity in older adults. Forty-three women (n = 25) and men (n = 18) between the ages of 60-78 years wore an accelerometer for measurement of average daily steps and 30-min peak stepping cadence. A 400-m walk test was used to measure walking speed. No sex difference was found for average daily steps (p = .76), average peak cadence (p = .96), or walking speed (p = .89). Daily steps (women: r = .68, p < .01; men: r = .04) and peak cadence (women: r = .81, p < .01; men: r = −.16) were positively correlated with walking speed in women but not in men. After controlling for daily steps, peak cadence remained significantly associated with walking speed in women (partial r = .61, p < .01). Walking intensity during daily ambulation is independently related to functional walking capacity in older adults, albeit this relation may be more significant for women than men.

Vascular aging as measured by central arterial stiffness contributes to slow walking speed in older adults, but the impact of age-related changes in peripheral vascular function on walking performance is unclear. The aim of this study was to test the hypothesis that calf muscle-specific vasodilator responses are associated with walking performance fatigue in healthy older adults. Forty-five older (60–78 yrs) adults performed a fast-paced 400 m walk test. Twelve of these adults exhibited fatigue as defined by slowing of walking speed (≥ 0.02 m/s) measured during the first and last 100 m segments of the 400 m test. Peak calf vascular conductance was measured following 10 min of arterial occlusion using strain-gauge plethysmography. Superficial femoral artery (SFA) vascular conductance response to graded plantar-flexion exercise was measured using Doppler ultrasound. No difference was found for peak calf vascular conductance between adults that slowed walking speed and those that maintained walking speed (p > 0.05); however, older adults that slowed walking speed had a lower SFA vascular conductance response to calf exercise (at highest workload: slowed group, 2.4 ± 0.9 vs. maintained group, 3.6 ± 0.9 ml/kg/min/mm Hg; p < 0.01). Moreover, the initial increase in SFA vascular conductance from rest to exercise was positively correlated with the change in walking speed for all adults (rho = 0.41, p = 0.005). In conclusion, these results suggest that calf exercise hemodynamics are associated with walking performance fatigability in older adults.

Summary Arterial stiffening is a widely known physiological change that occurs with ageing, but the functional consequences of vascular ageing are unclear. The purpose of this study was to determine whether carotid–femoral pulse wave velocity (PWV), mechanical properties of the carotid and femoral arteries and/or peripheral perfusion was associated with gait performance measured using a 400-m walk test. Twenty-one healthy older (68 ± 5 years) adults without cardiovascular disease participated in this study. Applanation tonometry was used to measure PWV, and Doppler ultrasound was used to measure arterial wall properties of the left common carotid and common femoral artery along with femoral blood flow. The median walk distance in the first 2 min of the test was 585 ft, and the overall gait speed was 1·5 m s−1. Gait performance was inversely correlated with PWV (distance: r = -0·51; speed: r = −0·48; P

Regular physical activity (PA) has numerous health benefits, many of which are directly relevant to menopausal women such as reduction in the risk for cardiovascular disease, diabetes, osteopenia and osteoporosis, some cancers, as well as depression.1 One area in which support for the beneficial influence of PA remains unconvincing is its effect on vasomotor symptoms. Vasomotor symptoms affect the majority of American women as they transition through menopause, and for some these symptoms become severe enough to negatively impact daily functioning and quality of life.2–5 Disheartening for many women is also the finding that vasomotor symptoms last much longer than previously thought (>5–8 years on average), with 10% of women experiencing these symptoms as long as 12 years post menopause.6,7 Most women are reluctant to treat their symptoms with pharmacological approaches, and opt instead for more natural methods which may include behavior modification through PA. Reviews of research examining the effects of exercise and other forms of PA on vasomotor symptoms attest to the growing interest in pursuing PA as a modality for symptom management.8–11 The overall conclusion nonetheless remains that there is insufficient evidence that PA alleviates vasomotor symptoms. Moreover, one study documented an increase in self-reported vasomotor symptoms in some women as part of a year-long exercise intervention trial.12 In another laboratory-based study, objectively measured vasomotor symptoms increased within 24 hours following a moderate-intensity exercise bout.13 Perceived physical exertion also preceded hot flashes (HFs) in a study involving two days of ambulatory HF monitoring in a real-life setting.14 HFs are believed to serve a heat dissipating function. Specifically, the thermoregulatory model posits that HFs are caused by altered neurotransmitter release in the hypothalamus, disrupting the regulation of the thermoregulatory center such that the core body temperature threshold for sweating is lowered, reducing the thermoneutral zone (i.e, sweating occurs at lower body core temperature).15,16 PA increases body core temperature and might thus stimulate more HFs, especially when performed at high exercise intensities or for long durations. On the other hand, a protective role of PA for alleviating HFs may be expected given its other neuroendocrine17,18,19, body composition, thermoregulation, fitness and psychological effects 20–22. There are no sufficiently powered randomized controlled trials of aerobic exercise targeting HFs as the primary outcome.11 The remaining studies are limited by the absence of both subjective and objective measures of PA and menopausal HFs. Consequently, it is unclear whether acute or chronic PA impacts primarily processes involved in symptom perception and reporting or whether any of the aforementioned physiological mechanisms are at play and having any discernible impact on objectively measured HFs. Thus, the present study had two main purposes. First, we sought to evaluate whether an acute bout of moderate-intensity aerobic exercise increases subjective and objective vasomotor symptoms, as previously reported by Freedman and Krell.13 Second, we examined whether objectively measured PA is associated with subjective HFs across a two-week monitoring period “in a real life setting” during which HFs were self-reported on a personal digital assistant (PDA) device. At the same time, we evaluated whether there are individual differences in the responses to acute exercise and daily PA associated with characteristics (cardiorespiratory fitness, weight status, or menopausal status) likely to influence the relation between PA and HFs.9,23–25

Leg exercise hemodynamics during single-leg knee extensions were compared among healthy groups of early perimenopausal (n = 15), late perimenopausal (n = 12), and early postmenopausal (n = 11) women. Femoral blood flow (FBF) and vascular conductance (FVC) at rest and during very light work rates (0 and 5 W) were similar among all three menopause stage groups. Vascular responses at 10 W (FBF) and 20 W (FBF and FVC) were significantly higher (P < 0.05) in early perimenopausal compared with late perimenopausal women. At 15 and 25 W, FBF and FVC were similar between late perimenopausal and early postmenopausal groups but higher (P < 0.05) in early perimenopausal women as compared with the other two menopausal groups. In the combined sample of all three menopause stage groups, follicle-stimulating hormone was significantly correlated with vascular conductance during submaximal (15 W) exercise (R = –0.56, P < 0.001), even after adjustment for age, fitness, LDL cholesterol, and abdominal fat (R = –0.46, P = 0.005). Collectively, these findings suggest that in middle-aged women, there is an association between menopause stage and leg vascular responsiveness during exercise.

Previous studies have demonstrated that carbonic anhydrase inhibition with acetazolamide reduces exercise capacity. The mechanism responsible for this early fatigue is unclear, but may be partly mediated by impaired respiratory muscle function. Inspiratory muscle strength and endurance were assessed in seven healthy men (age 28 ± 5 yrs, ±SD) by measuring maximal inspiratory pressure (MIP) and time to task failure during a constant-load breathing test (CLBT), respectively, under control (CON) and acetazolamide (ACZ; 500 mg/8 h po for 3 days) conditions that were separated by two weeks and randomized between subjects. In addition, MIP was measured before and after moderate-intensity cycling exercise to fatigue while pulmonary gas exchange, plasma pH, and ventilation were measured during exercise. ACZ did not alter pulmonary function (FVC, FEV1, MVV) or MIP measured at rest (CON, -157 ± 47 vs. ACZ, -154 ± 45 cmH(2)O, p>0.05), but decreased time to task failure during the CLBT (CON, 1340 ± 820 vs. ACZ, 698 ± 434 s; p=0.01). Exercise duration during cycling exercise was reduced (p=0.003) with ACZ (1090 ± 254 s) compared to CON (1944 ± 532 s) in the presence of a significantly lower plasma pH and higher ventilation compared to control (p