Impact of a Novel Training Approach on Hemodynamic and Vascular Profiles in Older Adults.

Exercise training beneficially moderates the effects of vascular aging. This study compared the efficacy of Peripheral Remodeling through Intermittent Muscular Exercise (PRIME), a novel training regimen, versus aerobic training on hemodynamic profiles in participants ≥70 years at risk for losing functional independence. Seventy-five participants (52 females, age: 76 ± 5 years) were assessed for hemodynamic and vascular function at baseline, after 4 weeks of either PRIME or aerobic training (Phase 1) and again after a further 8 weeks of aerobic and resistance training (Phase 2). Data were analyzed using 2 × 2 repeated-measures analysis of variance models on the change in each dependent variable. PRIME demonstrated reductions in brachial and aortic mean arterial pressure and diastolic blood pressure (p < .05) from baseline after Phase 1, which were sustained throughout Phase 2. Earlier and greater reductions in blood pressure following PRIME support the proposal that peripheral muscular training could beneficial for older individuals commencing an exercise program.

Sitting decreases endothelial microparticles but not circulating angiogenic cells irrespective of lower leg exercises: a randomized cross-over trial.

NEW FINDINGS: What is the central question of this study? What are the cellular and molecular determinants of increased risk for cardiovascular disease from prolonged sitting? What is the main finding and its importance? Prolonged sitting, independent of calf raise interruption strategies, decreases microparticle counts linked to endothelial activation and apoptosis. An acute bout of prolonged sitting appears to promote paradoxical decreases in microparticle counts, but the implications are not yet clear. ABSTRACT: Repeated exposure to prolonged sitting increases the risk for cardiovascular disease. However, the cellular links by which repeated exposure to prolonged sitting lead to increased cardiovascular risk have not been fully elucidated, with markers of vascular damage and repair such as microparticles (MPs) and circulating angiogenic cell (CACs) being promising targets. The objective of the study was to examine the effects of 3 h of sitting with or without intermittent calf raises on annexin V+ /CD34+ , annexin V+ /CD62E+ , and annexin V+ /CD31+ /42b- MP populations linked to CAC paracrine activity, endothelial activation and apoptosis, respectively, as well as CD14+ /31+ , CD3+ /31+ , and CD34+ CACs, which are linked to endothelial repair. In a random order, 20 sedentary participants (14 females, 22 ± 3 years) remained seated for 180 min with or without performing 10 calf raises every 10 min. Blood samples were obtained after 20 min of quiet rest in the supine position before and after sitting. Overall, sitting decreased annexin V+ /CD34+ MPs (-12 ± 5 events µl-1 , P < 0.01), annexin V+ /CD62E+ MPs (-17 ± 4 events µl-1 , P < 0.001), and annexin V+ /CD31+ /42b- MPs (-22 ± 6 events µl-1 , P < 0.001) regardless of condition. There were no differences in endothelin-1 plasma concentration, CD14+ /31+ , CD34+ or CD3+ /31+ CAC frequencies. Sitting did not alter CAC number, but decreased MPs linked to endothelial activation, apoptosis and CAC paracrine activity in a manner that was independent of muscle contraction. These findings support changes in markers of endothelial activation and apoptosis with sedentary behaviour and provide new insights into altered intercellular communication with physical inactivity such as prolonged sitting.

Endothelium function dependence of acute changes in pulse wave velocity and flow-mediated slowing.

Flow-mediated slowing (FMS), defined as the minimum pulse wave velocity (PWVmin) during reactive hyperemia, is potentially a simple, user-objective test for examining endothelial function. The purpose of the current study was to determine the effects of a known endothelial dysfunction protocol on arm PWV and PWVmin. Complete data were successfully collected in 22 out of 23 healthy adults (23.8 years [SD 4.1], 16 F, 22.8 kg/m2 [SD 2.8]). Local endothelial dysfunction was induced by increasing retrograde shear stress in the upper arm, through inflation of a distal (forearm) tourniquet to 75 mmHg, for 30 min. Pre- and post-endothelial dysfunction, PWV was measured followed by simultaneous assessment of PWVmin and flow-mediated dilation (FMD). PWV was measured between the upper arm and wrist using an oscillometric device, and brachial FMD using ultrasound. FMD (%) and PWVmin (m/s) were calculated as the maximum increase in diameter and minimum PWV during reactive hyperemia, respectively. Endothelial dysfunction resulted in a large effect size (ES) decrease in FMD (∆ = -3.10%; 95% CI: -4.15, -2.05; ES = -1.3), and a moderate increase in PWV (∆ = 0.38 m/s; 95% CI: 0.07, 0.69; ES = 0.5) and PWVmin (∆ = 0.16 m/s; 95% CI: 0.05, 0.28; ES = 0.6). There was a large intra-individual (pre- vs post-endothelial dysfunction) association between FMD and PWVmin (r = -0.61; 95% CI: -0.82, -0.24). In conclusion, acute change in PWV and PWVmin are at least partially driven by changes in endothelial function.

Acute cardiovascular response to unilateral, bilateral, and alternating resistance exercise with blood flow restriction.

AIM: Blood flow restriction (BFR) exercise is a common alternative to traditional high-load resistance exercise used to increase muscle size and strength. Some populations utilizing BFR at a low load may wish to limit their cardiovascular response to exercise. Different contraction patterns may attenuate the cardiovascular response, but this has not been compared using BFR. PURPOSE: To compare the cardiovascular response to unilateral (UNI), bilateral (BIL), and alternating (ALT) BFR exercise contraction patterns. METHODS: Twenty healthy participants performed four sets (30 s rest) of knee extensions to failure, using 30% one-repetition maximum, 40% arterial occlusion pressure, and each of the three contraction patterns (on different days, at the same time of day, separated by 2-10 days, randomized). Cardiovascular responses, presented as pre- to post-exercise mean changes (SD), were measured using pulse wave analysis and analyzed with Bayesian RMANOVA. RESULTS: ALT caused greater changes in: aortic systolic [ΔmmHg: ALT = 21(8); UNI = 13(11); BIL = 15(8); BF10 = 29.599], diastolic [ΔmmHg: ALT = 13(8); UNI = 7(11); BIL = 8(8); BF10 = 5.175], and mean arterial [ΔmmHg: ALT = 19(8); UNI = 11(11); BIL = 13(7); BF10 = 48.637] blood pressures. Aortic [ΔmmHg bpm: ALT = 4945(2340); UNI = 3294(1408); BIL = 3428 (1461); BF10 = 113.659] and brachial [ΔmmHg bpm: ALT = 6134(2761); UNI = 4300(1709); BIL = 4487(1701); BF10 = 31.845] rate pressure products, as well as heart rate [Δbpm: ALT = 26(14); UNI = 19(8); BIL = 19(11); BF10 = 5.829] were greatest with ALT. Augmentation index [Δ%: UNI = -6(13); BIL = - 7(11); ALT = - 5(16); BF10 = 0.155] and wave reflection magnitude [Δ%: UNI = - 5(9); BIL = - 4(7); ALT = - 4(7); BF10 = 0.150] were not different. CONCLUSION: Those at risk of a cardiovascular event may choose unilateral or bilateral BFR exercise over alternating until further work determines the degree to which it can be tolerated.

Physical Activity and Pain in Youth With Sickle Cell Disease.

Study objectives were to examine the relationships between physical activity, pain, and psychological distress in youth 8 to 17 years of age with sickle cell disease. Participants were 206 youth with sickle cell disease (M = 11.73 years, 54.9% female, 99.5% African American). Caregivers and youth completed a clinical psychosocial screening battery. Results revealed frequent pain (37.6%), moderate median pain intensity, and elevated median pain interference in youth. Lower caregiver-reported physical activity was associated with worse pain outcomes. Increased anxiety was also associated with worse pain outcomes. A better understanding of the relationship between physical activity/inactivity and pain will guide multifactorial treatment interventions.

Central cardiovascular hemodynamic response to unilateral handgrip exercise with blood flow restriction.

AIM: Exercise training with blood flow restriction (BFR) increases muscle size and strength. However, there is limited investigation into the effects of BFR on cardiovascular health, particularly central hemodynamic load. PURPOSE: To determine the effects of BFR exercise on central hemodynamic load (heart rate-HR, central pressures, arterial wave reflection, and aortic stiffness). METHODS: Fifteen males (age = 25 ± 2 years; BMI = 27 ± 2 kg/m2, handgrip max voluntary contraction-MVC = 50 ± 2 kg) underwent 5-min bouts (counter-balanced, 10 min rest between) of rhythmic unilateral handgrip (1 s squeeze, 2 s relax) performed with a moderate-load (60% MVC) with and without BFR (i.e., 71 ± 5% arterial inflow flow reduction, assessed via Doppler ultrasound), and also with a low-load (40% MVC) with BFR. Outcomes included HR, central mean arterial pressure (cMAP), arterial wave reflection (augmentation index, AIx; wave reflection magnitude, RM%), aortic arterial stiffness (pulse wave velocity, aPWV), and peripheral (vastus lateralis) microcirculatory response (tissue saturation index, TSI%). RESULTS: HR increased above baseline and time control for all handgrip bouts, but was similar between the moderate load with and without BFR conditions (moderate-load with BFR = + 9 ± 2; moderate-load without BFR = + 8 ± 2 bpm, p < 0.001). A similar finding was noted for central pressure (e.g., moderate load with BFR, cMAP = + 14 ± 1 mmHg, p < 0.001). No change occurred for RM% or AIx (p > 0.05) for any testing stage. TSI% increased during the moderate-load conditions (p = 0.01), and aPWV increased above baseline following moderate-load handgrip with BFR only (p = 0.012). CONCLUSIONS: Combined with BFR, moderate load handgrip training with BFR does not significantly augment central hemodynamic load during handgrip exercise in young healthy men.

Reliability of muscle blood flow and oxygen consumption response from exercise using near-infrared spectroscopy.

NEW FINDINGS: What is the central question of this study? Continuous-wave near-infrared spectroscopy, coupled with venous and arterial occlusions, offers an economical, non-invasive alternative to measuring skeletal muscle blood flow and oxygen consumption, but its reliability during exercise has not been established. What is the main finding and its importance? Continuous-wave near-infrared spectroscopy devices can reliably assess local skeletal muscle blood flow and oxygen consumption from the vastus lateralis in healthy, physically active adults. The patterns of response exhibited during exercise of varying intensity agree with other published results using similar methodologies, meriting potential applications in clinical diagnosis and therapeutic assessment. Near-infrared spectroscopy (NIRS), coupled with rapid venous and arterial occlusions, can be used for the non-invasive estimation of resting local skeletal muscle blood flow (mBF) and oxygen consumption (mV̇O2), respectively. However, the day-to-day reliability of mBF and mV̇O2 responses to stressors such as incremental dynamic exercise has not been established. The aim of this study was to determine the reliability of NIRS-derived mBF and mV̇O2 responses from incremental dynamic exercise. Measurements of mBF and mV̇O2 were collected in the vastus lateralis of 12 healthy, physically active adults [seven men and five women; 25 (SD 6) years old] during three non-consecutive visits within 10 days. After 10 min rest, participants performed 3 min of rhythmic isotonic knee extension (one extension every 4 s) at 5, 10, 15, 20, 25 and 30% of maximal voluntary contraction (MVC), before four venous occlusions and then two arterial occlusions. The mBF and mV̇O2 increased proportionally with intensity [from 0.55 to 7.68 ml min-1  (100 ml)-1 and from 0.05 to 1.86 ml O2  min-1  (100 g)-1 , respectively] up to 25% MVC, where they began to plateau at 30% MVC. Moreover, an mBF/mV̇O2 muscle oxygen consumption ratio of ∼5 was consistent for all exercise stages. The intraclass correlation coefficient for mBF indicated high to very high reliability for 10-30% MVC (0.82-0.9). There was very high reliability for mV̇O2 across all exercise stages (intraclass correlation coefficient 0.91-0.96). In conclusion, NIRS can reliably assess muscle blood flow and oxygen consumption responses to low- to moderate-intensity exercise, meriting potential applications in clinical diagnosis and therapeutic assessment.

Influence of physical inactivity on arterial compliance during a glucose challenge.

NEW FINDINGS: What is the central question of this study? To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. What is the main finding and its importance? During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day-1 ) and not when they were engaging in regular physical activity (>10,000 steps day-1 ). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia. ABSTRACT: Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co-morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High-resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat-to-beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day-1 ). Compliance and ß-stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or ß-stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2  mmHg-1 versus 120 min OGTT, 0.06 ± 0.02 mm2  mmHg-1 ; P < 0.001) and femoral ß-stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.

Influence of aerobic fitness on vasoreactivity in young men.

Previous work has demonstrated a direct relationship between aerobic fitness and vasodilatory function (i.e., flow-mediated dilation; FMD); however, the relation between aerobic fitness and vasoconstrictor responsiveness (i.e., low flow-mediated constriction; L-FMC), and the overall vasoactive range (FMD + L-FMC) is unclear. PURPOSE: To test the hypothesis that L-FMC and the overall vasoactive range (FMD + L-FMC) will be related to aerobic fitness in young, healthy men. METHODS: Twenty men (age: 23 ± 5 years) were recruited, and divided evenly into a higher (HF) vs. lower (LF) aerobic fitness group, quantified via YMCA cycle ergometry (VO2 peak extrapolation), and a 3-min step test (1-min heart rate recovery). Duplex Doppler-ultrasound was used to assess brachial artery FMD and L-FMC. RESULTS: Estimated VO2 peak (HF = 55 ± 10 vs. LF = 38 ± 5 mL/kg/min) and heart rate recovery (HF = 36 ± 10 vs. LF = 25 ± 8 beats) were greater in the HF group (P < 0.05). FMD and the vasoactive range were similar between groups; however, L-FMC was significantly greater in HF (HF = -2.5 ± 1.6 vs. LF = -0.7 ± 1.8%, P < 0.05; d = 1.18). A correlational analysis revealed an inverse relationship between L-FMC and both HR recovery (r = -0.665, P < 0.01) and estimated VO2 peak (r = -0.5, P < 0.05). CONCLUSIONS: This work supports an association between L-FMC and aerobic fitness in young, healthy men. Longitudinal or interventional studies are warranted to support causality, and to distinguish whether L-FMC is more sensitive to changes in aerobic fitness than FMD.

Impact of prolonged sitting on lower and upper limb micro- and macrovascular dilator function.

NEW FINDINGS: What is the central question of this study? The prevalence of sedentary behaviour in the workplace and increased daily sitting time have been associated with the development of cardiovascular disease; however, studies investigating the impact of sitting on vascular function remain limited. What is the main finding and its importance? We demonstrate that there is a marked vulnerability of the vasculature in the lower and upper limbs to prolonged sitting and highlight the importance of physical activity in restoring vascular function in a limb-specific manner. Sedentary behaviour in the workplace and increased daily sitting time are on the rise; however, studies investigating the impact of sitting on vascular function remain limited. Herein, we hypothesized that 6 h of uninterrupted sitting would impair limb micro- and macrovascular dilator function and that this impairment could be improved with a bout of walking. Resting blood flow, reactive hyperaemia to 5 min cuff occlusion (microvascular reactivity) and associated flow-mediated dilatation (FMD; macrovascular reactivity) were assessed in popliteal and brachial arteries of young men at baseline (Pre Sit) and after 6 h of uninterrupted sitting (Post Sit). Measures were then repeated after a 10 min walk (~1000 steps). Sitting resulted in a marked reduction of resting popliteal artery mean blood flow and mean shear rate (6 h mean shear rate, -52 ± 8 s(-1) versus Pre Sit, P < 0.05). Interestingly, reductions were also found in the brachial artery (6 h mean shear rate, -169 ± 41 s(-1) versus Pre Sit, P < 0.05). Likewise, after 6 h of sitting, cuff-induced reactive hyperaemia was reduced in both the lower leg (-43 ± 7% versus Pre Sit, P < 0.05) and forearm (-31 ± 11% versus Pre Sit, P < 0.05). In contrast, popliteal but not brachial artery FMD was blunted with sitting. Notably, lower leg reactive hyperaemia and FMD were restored after walking. Collectively, these data suggest that prolonged sitting markedly reduces lower leg micro- and macrovascular dilator function, but these impairments can be fully normalized with a short bout of walking. In contrast, upper arm microvascular reactivity is selectively impaired with prolonged sitting, and walking does not influence this effect.

Effect of aging on carotid baroreflex control of blood pressure and leg vascular conductance in women.

Recent work suggests that ß-adrenergic vasodilation offsets α-adrenergic vasoconstriction in young women, but this effect is lost after menopause. Given these age-related vascular changes, we tested the hypothesis that older women would exhibit a greater change in vascular conductance following baroreflex perturbation compared with young women. In 10 young (21 ± 1 yr) and 10 older (62 ± 2 yr) women, mean arterial pressure (MAP; Finometer), heart rate (HR), cardiac output (CO; Modelflow), total vascular conductance (TVC), and leg vascular conductance (LVC, duplex-Doppler ultrasound) were continuously measured in response to 5-s pulses of neck suction (NS; -60 Torr) and neck pressure (NP; +40 Torr) to simulate carotid hypertension and hypotension, respectively. Following NS, decreases in MAP were similar between groups; however, MAP peak response latency was slower in older women (P < 0.05). Moreover, at the time of peak MAP, increases in LVC (young, -11.5 ± 3.9%LVC vs. older, +19.1 ± 7.0%LVC; P < 0.05) and TVC were greater in older women, whereas young women exhibited larger decreases in HR and CO (young, -10 ± 3% CO vs. older, +0.8 ± 2% CO; P < 0.05). Following NP, increases in MAP were blunted (young, +14 ± 1 mmHg vs. older, +8 ± 1 mmHg; P < 0.05) in older women, whereas MAP response latencies were similar. Interestingly, decreases in LVC and TVC were similar between groups, but HR and CO (young, +7.0 ± 2% CO vs. older, -4.0 ± 2% CO; P < 0.05) responses were attenuated in older women. These findings suggest that older women have greater reliance on vascular conductance to modulate MAP via carotid baroreflex, whereas young women rely more on cardiac responsiveness. Furthermore, older women demonstrate a blunted ability to increase MAP to hypotensive stimuli.

The role of α-adrenergic receptors in mediating beat-by-beat sympathetic vascular transduction in the forearm of resting man.

Sympathetic vascular transduction is commonly understood to act as a basic relay mechanism, but under basal conditions, competing dilatory signals may interact with and alter the ability of sympathetic activity to decrease vascular conductance. Thus, we determined the extent to which spontaneous bursts of muscle sympathetic nerve activity (MSNA) mediate decreases in forearm vascular conductance (FVC) and the contribution of local α-adrenergic receptor-mediated pathways to the observed FVC responses. In 19 young men, MSNA (microneurography), arterial blood pressure and brachial artery blood flow (duplex Doppler ultrasound) were continuously measured during supine rest. These measures were also recorded in seven men during intra-arterial infusions of normal saline, phentolamine (PHEN) and PHEN with angiotensin II (PHEN+ANG). The latter was used to control for increases in resting blood flow with α-adrenergic blockade. Spike-triggered averaging was used to characterize beat-by-beat changes in FVC for 15 cardiac cycles following each MSNA burst and a peak response was calculated. Following MSNA bursts, FVC initially increased by +3.3 ± 0.3% (P = 0.016) and then robustly decreased to a nadir of -5.8 ± 1.6% (P < 0.001). The magnitude of vasoconstriction appeared graded with the number of consecutive MSNA bursts; while individual burst size only had a mild influence. Neither PHEN nor PHEN+ANG infusions affected the initial rise in FVC, but both infusions significantly attenuated the subsequent decrease in FVC (-2.1 ± 0.7% and -0.7 ± 0.8%, respectively; P < 0.001 vs. normal saline). These findings indicate that spontaneous MSNA bursts evoke robust beat-by-beat decreases in FVC that are exclusively mediated via α-adrenergic receptors.

Occupational sitting and work engagement among university employees.

Objective: This study sought to determine the relationship between occupational sitting and work engagement among university employees. Participants: Participants included 103 university employees (age: 48.5 ± 10.4 years, 80% female, 77% staff). Methods: Participants completed an online survey based on the Utrecht Work Engagement Survey (UWES) and the Occupational Sitting and Physical Activity Questionnaire (OSPAQ). The UWES assessed elements of work engagement. The OSPAQ assessed time spent sitting, standing, walking, and in heavy labor during a workday. Results: Compared to staff members, faculty members self-reported less time seated during the workday (373.8 ± 109.7 min/day vs. 321.1 ± 97.3 min/day, p = 0.03). Work engagement was comparable among faculty and staff members (vigor: p = 0.44; absorption: p = 0.68; dedication: p = 0.71). Associations of work engagement with occupational sitting were not significant. Conclusions: These pilot findings suggest that university staff tend to engage in more occupational sitting compared to faculty. Being absorbed and engaged at work is not associated with occupational sitting.

Influence of compressive gear on powerlifting performance: role of blood flow restriction training.

This study investigated the effects of powerlifting gear on training volume and performance, defined by the squat, bench press, and deadlift. Eighteen powerlifters (18-26 years) were randomized into either a group that trained and competed using compressive gear (CG) or without the gear (NON). Training volume, volume progression, and powerlifting performance were assessed before and after 10 weeks of training. Training volume increased in the first 4 weeks for both groups. Volume lifted for squat and the totals were greater in the CG. There was an increase in squat (19.05 ± 30.97 lb, p = 0.02), deadlift (19.05 ± 21.17 lb, p = 0.001), and the total score (44.00 ± 60.44 lb, p = 0.005) for both the groups. The improvements in squat (CG = 33.85 vs. NON = 5.74, p = 0.07) and totals (CG = 66.59 vs. NON = 23.67, p = 0.15) were greater in the CG. Both groups showed a significant and similar increase in the Wilks scores (+13.54 points, p = 0.03). There was a trend toward greater volume progression in those wearing CG during the initial stages of training. Both the groups significantly improved performance for the squat, and deadlift, and had higher totals, and Wilks scores, indicating significant strength gains. The greater magnitude of improvements in the squat and totals for the CG lifters suggests an ergogenic potential of training with powerlifting gear.

Impact of Acute Uninterrupted Sitting on Cerebrovascular Hemodynamics.

Reductions in brain blood flow are associated with reduced cognitive function and cerebrovascular disease. Acute periods of uninterrupted sitting can lead to endothelial dysfunction, namely due to a reduction in shear stress and subsequent reduction in nitric oxide bioavailability. Little is known of the impact of sitting on brain health. The purpose was to determine the total brain blood flow response following a 60-minute bout of uninterrupted sitting. Using a parallel design, this study evaluated the impact of 60-minutes of sitting on total brain blood flow. Fifteen participants (n=15; age=24 ± 1yr; BMI=25 ± 1 kg/m2) sat, uninterrupted, for 60-minutes during the SIT protocol. To ascertain the contribution of blood pooling effects on total brain blood flow, ten participants (n=10; age=23±2yr; BMI=27±4 kg/m2) sat in a modified sitting (MOD) for 60-minutes. Finally, thirteen participants (n=13; age=23±3yr; BMI=26±4 kg/m2) remained supine for the duration of the 60-minutes as a time-control (TC). Brain blood flow was quantified through Doppler-ultrasound measurements of blood flow through the internal carotid (ICA) and vertebral (VA) arteries: (ICA blood flow + VA blood flow) × 2. Following the 60-minutes of sitting (SIT), there was a significant reduction in brain blood flow with time (p=0.001, η p 2 =0.05). Total brain blood flow did not significantly change in MOD (p=0.69, η p 2 =0.05) or TC (p=0.06, η p 2 =0.58) conditions. These findings indicate 60-minutes of sitting may alter cerebrovascular hemodynamics characterized by a reduction in total brain blood flow.

Electrically induced cycling and nutritional counseling for counteracting obesity after spinal cord injury: A pilot study.

Objective: The purpose of this pilot study was to determine the preliminary efficacy of interval functional electrical stimulation (FES) cycling combined with nutritional counseling in obese adults with SCI.Setting: Community-based individuals with chronic SCI.Participants: Ten participants with chronic SCI.Interventions: Participants were divided into 2 groups (1) FES cycling and nutritional counseling (FES & Nutri) and (2) nutritional counseling only (Nutri Only). The FES & Nutri group performed high intensity interval FES cycling for 30 min 3 times per week for 8 weeks and received nutritional counseling for 30 min once per week for 8 weeks. The Nutri Only group received the nutritional counseling only.Outcome Measures: Body composition (fat mass, lean mass, body fat percentage), blood glucose levels.Results: Participants in the FES & Nutri group had a statistically significant greater decrease in body fat percentage (M = -1.14) compared to those in the Nutri Only group (M = +0.28) and gained more lean mass in their legs (M = +0.66 kg) compared to the Nutri Only group (M = -1.05 kg).Discussion/Conclusion: The statistically significant decrease in body fat percentage for the FES & Nutri group provides evidence that further study is merited. Future studies should include larger numbers of participants and the possible introduction of a preliminary strengthening program before initiating interval FES cycling. In addition, an increase in exercise volume and a greater role for nutritional counseling should be considered in order to optimize the treatment for obesity.

Arterial stiffness responses to prolonged sitting combined with a high-glycemic-index meal: a double-blind, randomized crossover trial.

Regular exposure to uninterrupted prolonged sitting and the consumption of high-glycemic-index (HGI) meals is independently associated with increased cardiovascular disease risk. Sitting for as little as 1 h can impair the health of both peripheral and central arteries. However, it is currently unknown whether combined acute exposure to uninterrupted prolonged sitting and an HGI meal is more detrimental to global (peripheral and central) vascular health. The purpose of this study was to investigate the effect of prolonged sitting (3 h), following the consumption of an HGI or a low-glycemic-index (LGI) meal, on global pulse wave velocity (G-PWV). Eighteen healthy participants [70% female, mean (standard deviation, SD) age = 22.6 (3.1) yr, body mass index (BMI) = 25.5 (6.1) kg/m2] sat for 3 h after consuming an HGI or LGI meal. G-PWV was assessed by incorporating three PWV measures (carotid-femoral, brachial-femoral, and femoral-ankle). The effects of time (PRE vs. POST) and condition (LGI vs. HGI) were analyzed using linear mixed models. Following prolonged sitting, G-PWV increased by 0.29 m/s (i.e., PRE vs. POST). However, the condition (P = 0.987) and time × condition (P = 0.954) effects were nonsignificant. The current findings support previous research showing an increase in arterial stiffness with prolonged sitting. However, in young and healthy adults, the arterial stiffness response was not worsened through HGI meal consumption.NEW & NOTEWORTHY We used novel statistical techniques and study design characteristics to examine how the cardiovascular disruptions due to prolonged sitting are changed after the consumption of low- and high-glycemic-index meals. The current study indicates that changes in arterial stiffness due to prolonged sitting are not worsened in young, healthy adults after the consumption of a high-glycemic-index meal.

The Effects of Acute Exposure to Prolonged Sitting, With and Without Interruption, on Vascular Function Among Adults: A Meta-analysis.

BACKGROUND: Exposure to acute prolonged sitting can result in vascular dysfunction, particularly within the legs. This vascular dysfunction, assessed using flow-mediated dilation (FMD), is likely the consequence of decreased blood flow-induced shear stress. With mixed success, several sitting interruption strategies have been trialled to preserve vascular function. OBJECTIVES: The objectives of this meta-analysis were to (1) assess the effects of acute prolonged sitting exposure on vascular function in the upper- and lower-limb arteries, and (2) evaluate the effectiveness of sitting interruption strategies in preserving vascular function. Sub-group analyses were conducted to determine whether artery location or interruption modality explain heterogeneity. DATA SOURCES: Electronic databases (PubMed, Web of Science, SPORTDiscus, and Google Scholar) were searched from inception to January 2020. Reference lists of eligible studies and relevant reviews were also checked. STUDY SELECTION: Inclusion criteria for objective (1) were: (i) FMD% was assessed pre- and post-sitting; (ii) studies were either randomised-controlled, randomised-crossover, or quasi-experimental trials; (iii) the sitting period was ≥ 1 h; and (iv) participants were healthy non-smoking adults (≥ 18 years), and free of vascular-acting medication and disease at the time of testing. Additional inclusion criteria for objective (2) were: (i) the interruption strategy must have been during the sitting period; (ii) there was a control (uninterrupted sitting) group/arm; and (iii) the interruption strategy must have involved the participants actively moving their lower- or upper-limbs. APPRAISAL AND SYNTHESIS METHODS: One thousand eight hundred and two articles were identified, of which 17 (22 trials, n = 269) met inclusion criteria for objective (1). Of those 17 articles, 6 studies (9 trials, n = 127) met the inclusion criteria for objective (2). Weighted mean differences (WMD), 95% confidence intervals (95% CI), and standardised mean difference (SMD) were calculated for all trials using random-effects meta-analysis modelling. SMD was used to determine the magnitude of effect, where < 0.2, 0.2, 0.5, and 0.8 was defined as trivial, small, moderate, and large respectively. RESULTS: (1) Random-effects modelling showed uninterrupted bouts of prolonged sitting resulted in a significant decrease in FMD% (WMD = - 2.12%, 95% CI - 2.66 to - 1.59, SMD = 0.84). Subgroup analysis revealed reductions in lower- but not upper-limb FMD%. (2) Random-effects modelling showed that interrupting bouts of sitting resulted in a significantly higher FMD% compared to uninterrupted sitting (WMD = 1.91%, 95% CI 0.40 to 3.42, SMD = 0.57). Subgroup analyses failed to identify an optimum interruption strategy but revealed moderate non-significant effects for aerobic interventions (WMD = 2.17%, 95% CI - 0.34 to 4.67, SMD = 0.69) and simple resistance activities (WMD = 2.40%, 95% CI - 0.08 to 4.88, SMD = 0.55) and a trivial effect for standing interruptions (WMD = 0.24%, 95% CI - 0.90 to 1.38, SMD = 0.16). CONCLUSIONS: Exposure to acute prolonged sitting leads to significant vascular dysfunction in arteries of the lower, but not upper, limbs. The limited available data indicate that vascular dysfunction can be prevented by regularly interrupting sitting, particularly with aerobic or simple resistance activities.

Brachial artery retrograde flow increases with age: relationship to physical function.

The purpose of this study was to examine the flow velocity pattern of the brachial artery and to determine its relationship to measures of physical function. Subjects from the Louisiana Healthy Aging Study (n = 95; age = 84 +/- 10 years) were evaluated. Brachial artery flow velocities and dimensions were measured using high-resolution ultrasonography. The continuous scale of physical function and performance test (CS-PFP10) was used to assess physical function. This test is based on the performance of 11 activities of daily living. Total CS-PFP10 score was 39.51 +/- 21.21 U. Mean antegrade and retrograde velocities at rest were 14.2 +/- 4.7 and 3.6 +/- 2.2 cm/s, respectively. Ante-/retrograde ratio was 5.5 +/- 4.6. Brachial artery diameter was 4.3 +/- 0.7 mm. Pulse pressure and vascular conductance were 66 +/- 18 mmHg, and 0.9 +/- 0.5 ml/min/mmHg, respectively. Vascular conductance (r = -0.34), ante-/retrograde ratio (r = -0.42) and CS-PFP10 (r = -0.65) were inversely and retrograde velocity (r = 0.40) and pulse pressure (r = 0.36), were directly associated with age. Retrograde velocity was inversely related to vascular conductance (r = -0.27) and CS-PFP10 total score (r = -0.45). A MANOVA revealed that those with the higher CS-PFP10 scores had a lower retrograde velocity (P = 0.0001), but this association was, in part, age-dependent. Among nonagenarians (n = 52), those in the lower tertiles of the CS-PFP10 scores had significantly higher retrograde velocities compared to those in the higher tertiles (P = 0.035). These data indicate an increase in brachial retrograde velocity with age. These hemodynamic changes are related to a decline in physical function.