ABSTRACT
Frailty reflects age-related damage to multiple physiological systems. Executive dysfunction is often a presenting symptom of diseases characterized by cognitive impairment. A decline in cardiovascular health is associated with worse executive function. We tested the hypothesis that higher frailty would be associated with executive dysfunction and that cardiovascular health would mediate this relationship. Middle- and older-aged adults at baseline (n = 29,591 [51% female]) and 3-year follow-up (n = 25,488 [49% females]) from the Canadian Longitudinal Study on Aging (comprehensive cohort) were included. Frailty was determined at baseline from a 61-item index, a cumulative cardiovascular health score was calculated from 30 variables at baseline, and participants completed a word-color Stroop task as an assessment of executive function. Multiple linear regressions and mediation analyses of cardiovascular health were conducted between frailty, Stroop interference-condition reaction time, and cardiovascular health in groups stratified by both age and sex (middle-aged males [MM], middle-aged females [MF], older-aged males [OM], older-aged females [OF]). Frailty (MM, 0.15 ± 0.05; MF, 0.16 ± 0.06; OM, 0.21 ± 0.06; OF, 0.23 ± 0.06) was negatively associated with cardiovascular health (MM, 0.12 ± 0.08; MF, 0.11 ± 0.07; OM, 0.20 ± 0.10; OF, 0.18 ± 0.09; ß > 0.037, p < 0.001), as well as the Stroop reaction time at 3-year follow-up (MM, 23.7 ± 7.9; MF, 23.1 ± 7.3; OM, 32.9 ± 13.1; OF, 30.9 ± 12.0; ß > 2.57, p < 0.001) across all groups when adjusted for covariates. Cardiovascular health was a partial (~ 10%) mediator between frailty and reaction time, aside from MFs. In conclusion, higher frailty levels are associated with executive dysfunction, which was partially mediated by cardiovascular health. Strategies to improve frailty and better cardiovascular health may be useful for combatting the age-related decline in executive function.
ABSTRACT
Executive functions are among the first cognitive abilities to decline with age and age-related executive function slowing predisposes older adults to cognitive disorders and disease. Intermittent Lifestyle Physical Activity (ILPA) reflects brief, unplanned activity that occurs during routine daily activities and is operationalized as activity bouts <60s. Our understanding of short bouts of habitual physical activity and executive functions is limited. We tested the hypothesis that greater amounts of ILPA in moderate and vigorous intensity domains would be associated with better executive function in older adults. Forty older adults (26 females, 68 ± 6, >55 years; body mass index: 26.6 ± 4.3â kg/m2) completed a Trail-Making-Task and wore an activPAL 24-hr/day for 6.2 ± 1.8-days. For each intensity, total time and time spent in bouts <60â s were determined. Trail A (processing speed) and Trail B (cognitive flexibility) were completed in 25.8 ± 8.2â s and 63.2 ± 26.2â s, respectively. Non-parametric Spearman's rank correlations report that moderate ILPA (3.2 ± 3.2â min/day) and total-moderate physical activity (20.1 ± 16.0â min/day) were associated with faster Trail A (total-moderate physical activity: ρ=-0.48; moderate-ILPA: ρ = -0.50; both, p < 0.003) and Trail B time (total-moderate physical activity: ρ = 0.36; moderate-ILPA: ρ = -0.46; both, p < 0.020). However, the results show no evidence of an association with either vigorous physical activity or light physical activity (total time or ILPA bouts: all, p > 0.180). Moderate physical activity accumulated in longer bouts (>60â s) was not associated with Trail B time (p = 0.201). Therefore, more total moderate physical activity and shorter bouts (<60â s) may result in better executive functions in older adults.
ABSTRACT
PURPOSE: The nadir pressure responses to cardiac cycles absent of muscle sympathetic nerve activity (MSNA) bursts (or non-bursts) are typically reported in studies quantifying sympathetic transduction, but the information gained by studying non-bursts is unclear. We tested the hypothesis that longer sequences of non-bursts (≥8 cardiac cycles) would be associated with a greater nadir diastolic blood pressure (DBP) and that better popliteal artery function would be associated with an augmented reduction in DBP. METHODS: Resting beat-by-beat DBP (via finger photoplethysmography) and common peroneal nerve MSNA (via microneurography) were recorded in 39 healthy, adults (age 23.4 ± 5.3 years; 19 females). For each cardiac cycle absent of MSNA bursts, the mean nadir DBP (ΔDBP) during the 12 cardiac cycles following were determined, and separate analyses were conducted for ≥8 or < 8 cardiac cycle sequences. Popliteal artery endothelial-dependent (via flow-mediated dilation; FMD) and endothelial-independent vasodilation (via nitroglycerin-mediated dilation; NMD) were determined. RESULTS: The nadir DBP responses to sequences ≥8 cardiac cycles were larger (-1.40 ± 1.27 mmHg) than sequences <8 (-0.38 ± 0.46 mmHg; p < 0.001). In adjusting for sex and burst frequency (14 ± 8 bursts/min), larger absolute or relative FMD (p < 0.01), but not NMD (p > 0.53) was associated with an augmented nadir DBP. This overall DBP-FMD relationship was similar in sequences ≥8 (p = 0.04-0.05), but not <8 (p > 0.72). CONCLUSION: The DBP responses to non-bursts, particularly longer sequences, were inversely associated with popliteal endothelial function, but not vascular smooth muscle sensitivity. This study provides insight into the information gained by quantifying the DBP responses to cardiac cycles absent of MSNA.
Subject(s)
Blood Pressure , Popliteal Artery , Sympathetic Nervous System , Vasodilation , Humans , Male , Female , Popliteal Artery/physiology , Blood Pressure/physiology , Adult , Sympathetic Nervous System/physiology , Vasodilation/physiology , Vasodilation/drug effects , Young Adult , Endothelium, Vascular/physiology , Peroneal Nerve/physiology , Heart Rate/physiologyABSTRACT
BACKGROUND: More habitual time spent engaging in prolonged sedentary behaviors increases the risk of developing hypertension. Beat-by-beat systolic (SBPV) and diastolic blood pressure variability (DBPV) are more pronounced in persons with hypertension and may be an early manifestation of blood pressure dysregulation. We tested the hypothesis that a single bout of prolonged sitting augments very short-term SBPV and DBPV. The secondary aim was to explore sex differences in prolonged sitting-induced increases in SBPV and DBPV. METHODS: Thirty-three adults (22.9â ±â 1.9 years; 17 females) completed a single, 3-hour bout of prolonged sitting with beat-by-beat arterial pressure determined at baseline, 1.5-hour, and 3-hour via finger photoplethysmography. RESULTS: There were no sex differences observed for baseline brachial SBP (males: 122â ±â 10 mm Hg; females: 111â ±â 9 mm Hg), SBPV (males: 1.87â ±â 0.63 mm Hg; females: 1.51â ±â 0.38 mm Hg), DBP (males: 68â ±â 6 mm Hg; females: 66â ±â 8 mm Hg), or DBPV (males: 1.40â ±â 0.41 mm Hg; females: 1.27â ±â 0.32 mm Hg) (all, Pâ >â 0.41). In the pooled sample, baseline SBPV (1.68â ±â 0.54 mm Hg) remained unchanged after 1.5 hours (1.80â ±â 0.60 mm Hg; Pâ =â 0.59) but increased after 3.0 hours (1.84â ±â 0.52 mm Hg; Pâ =â 0.01). This post-sitting increase was driven by males (Pâ =â 0.009), with no difference observed in females (Pâ =â 1.00). Similarly, baseline DBPV (1.33â ±â 0.36 mm Hg) was similar after 1.5 hours (1.42â ±â 0.41 mm Hg; Pâ =â 0.72) but was increased at 3 hours (1.50â ±â 0.34 mm Hg; Pâ =â 0.02). However, no sex differences in DBPV (all, Pâ >â 0.07) were observed across the time points. CONCLUSIONS: In young, normotensive adults, a single bout of prolonged sitting augmented beat-by-beat blood pressure variability, which may provide a link between uninterrupted sitting and the development of blood pressure dysregulation.
Subject(s)
Sedentary Behavior , Sitting Position , Humans , Male , Female , Young Adult , Sex Factors , Time Factors , Blood Pressure/physiology , Adult , Photoplethysmography , Hypertension/physiopathology , Hypertension/diagnosis , Arterial PressureABSTRACT
INTRODUCTION: Single bouts of prolonged bent-legged sitting attenuate popliteal endothelial-dependent vasodilation (as assessed via flow-mediated dilation [FMD]), which is partially attributed to arterial 'kinking'. However, the impact of knee-flexion angle on sitting-induced popliteal FMD is unknown. The objective of this study was to perform separate laboratory and free-living studies to test the hypotheses that: (1) popliteal FMD impairments would be graded between knee flexions at 90° (bent-legged sitting) > 45° > 0° (straight-legged sitting) following a 3-hour bout of sitting; and (2) more habitual time spent bent-legged sitting (< 45°) would be associated with lower FMD. METHODS: The laboratory study included eight young, healthy adults (24 ± 2 years; four women) who underwent two sitting bouts over 2 days with one leg positioned at a knee-flexion angle of 0° or 90° and the opposite leg at 45° knee flexion. Popliteal FMD was assessed at pre- and postsitting timepoints. RESULTS: Sitting-induced reductions in FMD were similar between all knee-flexion angles (all, p > 0.674). The free-living study included 35 young, healthy adults (23 ± 3 years; 16 women) who wore three activPAL monitors (torso, thigh, shin) to determine detailed sedentary postures. Time spent sedentary (624 ± 127 min/day), straight-legged sitting (112 ± 98 min/day), and bent-legged sitting (442 ± 106 min/day) were not related to relative FMD (5.3 ± 1.8%; all, p > 0.240). CONCLUSION: These findings suggest that knee-flexion angle-mediated arterial 'kinking' during sitting is not a major contributor toward sitting-induced popliteal endothelial-dependent vasodilatory dysfunction.
Subject(s)
Healthy Volunteers , Knee Joint , Popliteal Artery , Sitting Position , Vasodilation , Humans , Female , Male , Young Adult , Popliteal Artery/diagnostic imaging , Popliteal Artery/physiopathology , Adult , Knee Joint/physiopathology , Time Factors , Endothelium, Vascular/physiopathology , Regional Blood Flow , Sedentary BehaviorABSTRACT
The metabolic cost of walking (MCOW), or oxygen uptake normalized to distance, provides information on the energy expended during movement. There are conflicting reports as to whether sex differences in MCOW exist, with scarce evidence investigating factors that explain potential sex differences. This study 1) tested the hypothesis that females exhibit a higher MCOW than males, 2) determined whether normalizing to stepping cadence ameliorates the hypothesized sex difference, and 3) explored whether more habitual step counts and time in intensity-related physical activity, and less sedentary time were associated with a decreased MCOW. Seventy-six participants (42 females, 24 ± 5 yr) completed a five-stage, graded treadmill protocol with speeds increasing from 0.89 to 1.79 m/s (6-min walking stage followed by 4-min passive rest). Steady-state oxygen uptake (via indirect calorimetry) and stepping cadence (via manual counts) were determined. Gross and net MCOW, normalized to distance traveled (km) and step-cadence (1,000 steps) were calculated for each stage. Thirty-nine participants (23 females) wore an activPAL on their thigh for 6.9 ± 0.4 days. Normalized to distance, females had greater gross MCOW (J/kg/km) at all speeds (P < 0.014). Normalized to stepping frequency, females exhibited greater gross and net MCOW at 1.12 and 1.79 m/s (J/kg/1,000 steps; P < 0.01) but not at any other speeds (P < 0.075). Stature was negatively associated with free-living cadence (r = -0.347, P = 0.030). Females expend more energy/kilometer traveled than males, but normalizing to stepping cadence attenuated these differences. Such observations provide an explanation for prior work documenting higher MCOW among females and highlight the importance of stepping cadence when assessing the MCOW.NEW & NOTEWORTHY Whether there are sex differences in the metabolic cost of walking (MCOW) and the factors that may contribute to these are unclear. We demonstrate that females exhibit a larger net MCOW than males. These differences were largely attenuated when normalized to stepping cadence. Free-living activity was not associated with MCOW. We demonstrate that stepping cadence, but not free-living activity, partially explains the higher MCOW in females than males.
Subject(s)
Energy Metabolism , Oxygen Consumption , Walking , Humans , Female , Male , Energy Metabolism/physiology , Adult , Walking/physiology , Oxygen Consumption/physiology , Young Adult , Exercise Test/methods , Sex Characteristics , Sex FactorsABSTRACT
Discharge of postganglionic muscle sympathetic nerve activity (MSNA) is related poorly to blood pressure (BP) in adults. Whether neural measurements beyond the prevailing level of MSNA can account for interindividual differences in BP remains unclear. The current study sought to evaluate the relative contributions of sympathetic-BP transduction and sympathetic baroreflex gain on resting BP in young adults. Data were analyzed from 191 (77 females) young adults (18-39 years) who underwent continuous measurement of beat-to-beat BP (finger photoplethysmography), heart rate (electrocardiography), and fibular nerve MSNA (microneurography). Linear regression analyses were computed to determine associations between sympathetic-BP transduction (signal-averaging) or sympathetic baroreflex gain (threshold technique) and resting BP, before and after controlling for age, body mass index, and MSNA burst frequency. K-mean clustering was used to explore sympathetic phenotypes of BP control and consequential influence on resting BP. Sympathetic-BP transduction was unrelated to BP in males or females (both R2 < 0.01; P > 0.67). Sympathetic baroreflex gain was positively associated with BP in males (R2 = 0.09, P < 0.01), but not in females (R2 < 0.01; P = 0.80), before and after controlling for age, body mass index, and MSNA burst frequency. K-means clustering identified a subset of participants with average resting MSNA, yet lower sympathetic-BP transduction and lower sympathetic baroreflex gain. This distinct subgroup presented with elevated BP in males (P < 0.02), but not in females (P = 0.10). Sympathetic-BP transduction is unrelated to resting BP, while the association between sympathetic baroreflex gain and resting BP in males reveals important sex differences in the sympathetic determination of resting BP.NEW & NOTEWORTHY In a sample of 191 normotensive young adults, we confirm that resting muscle sympathetic nerve activity is a poor predictor of resting blood pressure and now demonstrate that sympathetic baroreflex gain is associated with resting blood pressure in males but not females. In contrast, signal-averaged measures of sympathetic-blood pressure transduction are unrelated to resting blood pressure. These findings highlight sex differences in the neural regulation of blood pressure.
Subject(s)
Baroreflex , Hypertension , Young Adult , Humans , Male , Female , Blood Pressure/physiology , Baroreflex/physiology , Heart Rate/physiology , Sympathetic Nervous System , Muscle, Skeletal/innervationABSTRACT
Elevated pulse wave velocity (PWV) determined arterial stiffness is a prominent marker of cardiovascular disease (CVD) risk. Exercise training delays the progression of CVD, but existing reviews on the impact of training on PWV are conflicting. We synthesized the evidence on the effects of exercise training interventions on PWV. We searched Scopus, EMBASE, PubMed, CINAHL, and Academic Search Premier databases for systematic reviews including PWV, and examined the effects of exercise training on PWV. We screened 842 citations that resulted in 44 systematic reviews, including 22 meta-analyses [unique participants, n = 6,719 (3,390 females)]. Studies were conducted in general adults with/without disease(s) (n = 19, 8 meta-analyses), kidney disease (n = 9, 6 meta-analyses), increased CVD risk or CVD (n = 7, 5 meta-analyses), type 2 diabetes mellitus (n = 3, 2 meta-analyses), and other conditions (n = 6, 2 meta-analyses). In general adults, PWV was reduced by aerobic exercise (ß, -0.75 to -0.52 m/s) and low-to-moderate intensity resistance exercise training (ß, -0.34 m/s). Exercise training was beneficial for patients with kidney disease (ß, -1.13 to -0.56 m/s). Aerobic exercise improved PWV in adults with CVD or high CVD risk (ß, -0.70 to -0.42 m/s). Combined aerobic and resistance exercise training decreased carotid-femoral (CF) PWV in patients with CVD (ß, -1.15 m/s) and decreased brachial-ankle (BA) PWV in postmenopausal females (ß, -1.18 m/s). Neither aerobic nor combined training improved PWV in individuals with type 2 diabetes. The potential physiological mechanisms involved are discussed. Overall, the included systematic reviews and meta-analyses documented that exercise training was an effective strategy to improve PWV, but the optimal type of training varied between populations.
ABSTRACT
TAKE HOME MESSAGE: Our case study indicated that a bifurcated brachial artery exhibited worse vasodilatory responses relative to an intact contralateral artery.
Subject(s)
Brachial Artery , Vasodilation , Vasodilation/physiology , Brachial Artery/physiology , Endothelium, Vascular/physiology , Upper Extremity , Regional Blood FlowABSTRACT
Heart rate variability (HRV) is a well-established noninvasive marker of autonomic cardiac control. We test whether time spent sitting (negatively) versus lying (positively) influences vagal HRV outcomes. HRV (10 min supine electrocardiogram) and free-living postures (dual-accelerometer configuration, 7 days) were measured in 31 young healthy adults (15â, age: 23 ± 3 years). Habitual lying (66 ± 61 min/day), but not sitting time (558 ± 109 min/day), total sedentary time (623 ± 132 min/day), nor step counts (10 752 ± 3200 steps/day; all, p > 0.090), was associated with root mean square of successive cardiac interval differences (ρ = -0.409, p = 0.022) and normalized high-frequency HRV (ρ = -0.361, p = 0.046). These findings document a paradoxical negative impact of waking lying time on cardioautonomic function. Take home message Using a multi-accelerometer configuration, we demonstrated that more habitual waking time lying, but not sitting or total sedentary time, was associated with worse vagally mediated cardiac control.
Subject(s)
Heart , Vagus Nerve , Humans , Adult , Young Adult , Heart Rate/physiology , Vagus Nerve/physiology , Heart/physiology , Electrocardiography , Autonomic Nervous SystemABSTRACT
Objective. Approaches to differentiate sitting and lying are available within the default activPAL software from a single thigh-worn monitor. Dual-monitor methods use multiple monitors positioned on the thigh and torso to characterize sitting versus lying. We evaluated the validity between these two methods to measure waking, sitting, and lying time in free-living conditions. We also examined if the degree-threshold distinguishing sitting/lying for the dual-monitor (<30° and <45°) impacted results.Approach. Thirty-five young adults (24 ± 3 years, 16 females) wore an activPAL 24 h per day on their thigh and torso during free-living conditions (average: 6.8 ± 1.0 d, 239 total). Data were processed using the default activPAL software (thigh-only) or a custom MATLAB program (dual-monitor).Main results. The single-monitor recorded less lying time (59 ± 99 min d-1) and more sitting time (514 ± 203 min d-1) than the dual-monitor method regardless of 30° (lying: 85 ± 94 min d-1; sitting: 488 ± 166 min d-1) or 45° lying threshold (lying: 170 ± 142, sitting: 403 ± 164 min d-1; all,p< 0.001). The single monitor lying time was weakly correlated to the dual-monitor (30°:ρ= 0.25, 45°:ρ= 0.21; both,p< 0.001), whereas sitting was moderate-strong (30°:ρ= 0.76, 45°:ρ= 0.58; both,p< 0.001). However, the mean absolute error was 81 min d-1(30°) and 132 min d-1(45°) for both lying and sitting.Significance. The method of differentiating sitting/lying from a single thigh-worn activPAL records more sitting time and less lying time compared to a dual-monitor configuration (regardless of degree-threshold) that considered the position of the torso. A further refinement of algorithms or implementation of multiple-monitor methods may be needed for researchers to derive detailed sedentary positions.
Subject(s)
Posture , Social Conditions , Female , Young Adult , Humans , Accelerometry , Software , AlgorithmsSubject(s)
Muscle, Skeletal , Sympathetic Nervous System , Male , Humans , Female , Blood Pressure/physiology , Heart Rate/physiologyABSTRACT
Whole-day movement guidelines for improving health, recommend that adults engage in at least 150 min week-1 of moderate-to-vigorous aerobic physical activity and limit their sedentary time. In young adults, higher systolic blood pressure variability (BPV) is a precursor for the development of hypertension. The impact of habitual activity that comprises (inter)national guidelines on BPV is unclear. We tested the hypothesis that less habitual physical activity and greater sedentary time would be associated with larger BPV. Ninety-two normotensive participants [age: 19-38 years, body mass index (BMI): 23.6 ± 3.3 kg/m2, 44â] wore an activPAL monitor on their thigh for 7.0 ± 0.3 days. Ten minutes of supine systolic arterial pressure was measured via finger photoplethysmography (115 ± 11 mmHg). Beat-by-beat systolic BPV was measured using the average real variability index (1.1 ± 0.6 mmHg). Relationships between habitual activity outcomes and BPV were assessed via multiple regressions adjusted for age, sex, and BMI. Moderate-intensity physical activity (average: 36 ± 19 min day-1; ß = -0.010, p = 0.02) and time spent in sedentary bouts >1-h (245 ± 134 min day-1; ß = 0.002, p < 0.001), but not light-intensity activity, vigorous-intensity activity, standing time, sedentary breaks, or time spent in sedentary bouts <1-h (all, p > 0.10) were predictors of systolic BPV. Higher moderate physical activity and lower prolonged sedentary time were associated with attenuated systolic BPV responses in young adults. These findings highlight the cardiovascular benefits of habitual activity among younger adults and suggest that simple strategies such as reducing long periods of uninterrupted sitting and increasing moderate-intensity physical activity may be efficacious for reducing the risk of developing or delaying the onset of hypertension.
Subject(s)
Hypertension , Sedentary Behavior , Young Adult , Humans , Adult , Blood Pressure/physiology , Exercise , Hypertension/diagnosis , Hypertension/prevention & control , Body Mass IndexABSTRACT
BACKGROUND: Dysfunction of the endothelium is a key precursor of cardiovascular disease. Endothelial function, as assessed via the flow-mediated dilation test, is attenuated with chronic disease (e.g., type 2 diabetes mellitus, hypertension). Exercise training may mitigate this dysfunction and promote better vascular health. OBJECTIVE: The main objective of this umbrella review was to determine the impact of exercise training on flow-mediated dilation in healthy adults and those with chronic disease. METHODS: Studies were included if they conducted a systematic review and/or meta-analysis on flow-mediated dilation responses to exercise interventions in adults. Sources were searched in January 2022 and included Scopus, EMBASE, MEDLINE, CINAHL, and Academic Search Premier. National Institutes of Health quality assessment tools were used. The results were presented narratively. RESULTS: Twenty-seven systematic reviews, including 19 meta-analyses, (total: 5464 unique participants, 2181 reported unique female individuals) met the inclusion criteria. The average overall quality of included reviews was 8.8/11. The quality of studies within each included review varied from low to moderate using a variety of quality assessment scales. Reviews were conducted in healthy adults (n = 9, meta-analyses = 6), as well as those with type 2 diabetes (n = 5, meta-analyses = 4), cardiovascular conditions [i.e., conditions that impact the cardiovascular system, but excluding samples of only type 2 diabetes] (n = 11, meta-analyses = 7), and other chronic conditions (n = 2, meta-analyses = 2). Overall, the included reviews provided evidence that the type of training to optimally improve FMD may vary based on disease condition. Specifically, the evidence suggests that healthy adults benefitted most from higher intensity aerobic training and/or more frequent low-to-moderate resistance training. In addition, adults with type 2 diabetes benefitted most from low-intensity resistance or aerobic exercise training, whereas those with cardiovascular conditions should consider engaging in high-intensity aerobic training to improve endothelial function. CONCLUSIONS: This information may help guide the design of specific exercise programs or recommendations for adults with chronic conditions.
Subject(s)
Diabetes Mellitus, Type 2 , Humans , Adult , Female , Diabetes Mellitus, Type 2/therapy , Dilatation , Exercise , Exercise Therapy/methods , Chronic DiseaseABSTRACT
OBJECTIVES: Carotid intima-media-thickness (cIMT) is predictive of future cardiovascular events, increases with chronological age, and greater in males. The accumulation of health deficits (or frailty) is a marker of biological age. However, normative cIMT values are lacking and would be an important comparative tool for healthcare providers and researchers. This study aimed to establish sex-specific normative cIMT values across chronological age and frailty levels (i.e. biological age). METHODS: Frailty and right common cIMT data were extracted from the Canadian Longitudinal Study of Aging baseline comprehensive cohort of middle-aged and older adults (n = 10,209; 5000 females). cIMT was assessed via high-resolution ultrasound. Frailty was determined using a 52-item frailty index. Ordinary least squares and quantile regressions were conducted between age (years or frailty index) with cIMT (average or maximum), separately for males and females. RESULTS: In both sexes, average and maximum cIMT increased with higher chronological age and frailty. Both cIMT metrics increased non-linearly (quadratic-cIMT term) with advancing age (ß-coefficients for quadratic and linear terms: all, p < 0.001), except for the linear relationship between average and maximum cIMT with chronological age among males (p < 0.001). Sex-specific normative average and maximum cIMT values were established (1st-99th percentiles, 5% increments), separately for chronological and biological ages. CONCLUSIONS: This is the largest sample of adults to establish normative cIMT outcomes that includes older adults. The chronological age and frailty-related normative cIMT outcomes will serve as a useful resource for healthcare professionals and researchers to establish "normal" age- and sex-specific cIMT values.
ABSTRACT
A single bout of prolonged uninterrupted sitting increases oxidative stress, reduces popliteal blood flow-induced shear stress, and diminishes endothelium-dependent, flow-mediated dilation (FMD). The FMD response is also influenced by the sensitivity of vascular smooth muscle cells to nitric oxide (i.e., endothelium-independent dilation), which is also attenuated by elevated oxidative stress. However, it is currently unknown whether prolonged sitting impacts popliteal endothelium-independent dilation responses, which may uncover a novel mechanism associated with sitting-induced vascular dysfunction. This study tested the hypothesis that prolonged sitting attenuates both popliteal FMD and endothelium-independent, nitroglycerin-mediated dilation responses (NMD, 0.4 mg sublingual dose). Popliteal blood flow (mL/min), relative FMD (%), and NMD (%) were assessed via duplex ultrasonography before and after a â¼3-h bout of sitting in 14 young, healthy adults (8â; 22 ± 2 yr). Prolonged sitting attenuated resting blood flow (57 ± 23 to 32 ± 16 mL/min, P < 0.001), relative FMD (4.6 ± 2.8% to 2.2 ± 2.5%; P = 0.001), and NMD (7.3 ± 4.0% to 4.6 ± 3.0%; P = 0.002). These novel findings demonstrate that both endothelium-dependent and independent mechanisms contribute to the adverse vascular consequences associated with prolonged bouts of sitting.NEW & NOTEWORTHY We demonstrate that lower-limb vascular smooth muscle function is attenuated in young, healthy adults after an acute bout of prolonged sitting. These data indicate that prolonged sitting-induced vascular dysfunction involves both endothelium-dependent and -independent mechanisms.
Subject(s)
Endothelium, Vascular , Vasodilation , Humans , Adult , Vasodilation/physiology , Dilatation , Endothelium, Vascular/physiology , Popliteal Artery/physiology , Posture/physiology , Regional Blood Flow/physiology , Brachial Artery/physiologyABSTRACT
Objective monitors such as the activPAL characterize time when the thigh is horizontal as sedentary time. However, there are physiological differences between lying, bent-legged sitting, and straight-legged sitting. We introduce a three-monitor configuration to assess detailed sedentary postures and demonstrate its use in characterizing such positions in free-living conditions. We explored time spent in each sedentary posture between prolonged (>1 h) versus non-prolonged (<1 h) sedentary bouts. In total, 35 healthy adults (16â, 24 ± 3 years; 24 h/day for 6.8 ± 1.0 days) wore an activPAL accelerometer on their thigh, torso, and shin. Hip and knee joint flexion angle estimates were determined during sedentary bouts using the dot-product method between the torso−thigh and thigh−shin, respectively. Compared to lying (69 ± 60 min/day) or straight-legged sitting (113 ± 100 min/day), most time was spent in bent-legged sitting (439 ± 101 min/day, p < 0.001). Most of the bent-legged sitting time was accumulated in non-prolonged bouts (328 ± 83 vs. 112 ± 63 min/day, p < 0.001). In contrast, similar time was spent in straight-legged sitting and lying between prolonged/non-prolonged bouts (both, p > 0.26). We document that a considerable amount of waking time is accumulated in lying or straight-legged sitting. This methodological approach equips researchers with a means of characterizing detailed sedentary postures in uncontrolled conditions and may help answer novel research questions on sedentariness.
Subject(s)
Accelerometry , Social Conditions , Adult , Humans , Posture , Sitting Position , TorsoABSTRACT
BACKGROUND: Carotid intima-media thickness (cIMT) provides an index of arterial injury. Frailty is an indicator of vulnerability to adverse health outcomes. It is unclear whether cIMT is associated with the multi-dimensional frailty index and/or if this relationship is age- or sex-specific. The aim was to determine the impact of age and sex on the relationship between cIMT and frailty level in middle-aged and older adults. METHODS: Frailty and cIMT data were extracted from the Canadian Longitudinal Study of Aging baseline comprehensive cohort of middle-aged (45-64â¯years) and older adults (>65â¯years) (nâ¯=â¯10,209). cIMT was assessed via high-resolution ultrasound. Frailty was determined using a 52-item index. Covariate-adjusted ordinary least squares regressions were conducted separately for middle-aged males (nâ¯=â¯3178), middle-aged females (nâ¯=â¯3125), older males (nâ¯=â¯2031), and older females (nâ¯=â¯1875). RESULTS: Average cIMTs were larger in older versus middle-aged adults and in males versus females (all, pâ¯<â¯0.001). Average cIMT was positively associated with frailty level in adjusted linear regression models in middle-aged males [adj. R2â¯=â¯0.09; ßâ¯=â¯0.015 (95â¯% CI: 0.005-0.026), pâ¯=â¯0.004], middle-aged females [adj. R2â¯=â¯0.11; ßâ¯=â¯0.040 (95â¯% CI: 0.025-0.054), pâ¯<â¯0.001], older males [adj. R2â¯=â¯0.12; ßâ¯=â¯0.019 (95â¯% CI: 0.004-0.034), pâ¯=â¯0.01], and older females [adj. R2â¯=â¯0.11; ßâ¯=â¯0.020 (95â¯% CI: 0.002-0.039), pâ¯=â¯0.03]. CONCLUSION: cIMT was an independent contributor to frailty level regardless of age group (middle-aged/older adults) or sex, with the strongest effect observed in middle-aged females. Our cross-sectional study documents the independent relationship between a marker of cardiovascular function and an increased vulnerability to adverse health outcomes in middle-aged and older males and females.
Subject(s)
Carotid Intima-Media Thickness , Frailty , Male , Middle Aged , Female , Humans , Aged , Longitudinal Studies , Frailty/epidemiology , Cross-Sectional Studies , Canada/epidemiology , Aging , Risk FactorsABSTRACT
AIMS: Patients with sympathetic excess are those most likely to benefit from novel interventions targeting the autonomic nervous system. To inform such personalized therapy, we identified determinants of augmented muscle sympathetic nerve activity (MSNA) in heart failure, versus healthy controls. METHODS AND RESULTS: We compared data acquired in 177 conventionally-treated, stable non-diabetic patients in sinus rhythm, aged 18-79 years (149 males; 28 females; left ventricular ejection fraction [LVEF] 25 ± 11% [mean ± standard deviation]; range 5-60%), and, concurrently, under similar conditions, in 658 healthy, normotensive volunteers (398 males; aged 18-81 years). In heart failure, MSNA ranged between 7 and 90 bursts·min-1 , proportionate to heart rate (p < 0.0001) and body mass index (BMI) (p = 0.03), but was unrelated to age, blood pressure, or drug therapy. Mean MSNA, adjusted for age, sex, BMI, and heart rate, was greater in heart failure (+14.2 bursts·min-1 ; 95% confidence interval [CI] 12.1-16.3; p < 0.0001), but lower in women (-5.0 bursts·min-1 ; 95% CI 3.4-6.6; p < 0.0001). With spline modeling, LVEF accounted for 9.8% of MSNA variance; MSNA related inversely to LVEF below an inflection point of â¼21% (p < 0.006), but not above. Burst incidence was greater in ischaemic than dilated cardiomyopathy (p = 0.01), and patients with sleep apnoea (p = 0.03). Burst frequency correlated inversely with stroke volume (p < 0.001), cardiac output (p < 0.001), and peak oxygen consumption (p = 0.002), and directly with norepinephrine (p < 0.0001) and peripheral resistance (p < 0.001). CONCLUSION: Burst frequency and incidence exceeded normative values in only â¼53% and â¼33% of patients. Such diversity encourages selective deployment of sympatho-modulatory therapies. Clinical characteristics can highlight individuals who may benefit from future personalized interventions targeting pathological sympathetic activation.