Firefighter hemodynamic responses to different fire training environments.

Firefighting is associated with an increased risk for a cardiovascular (CV) event, likely due to increased CV strain. The increase in CV strain during firefighting can be attributed to the interaction of several factors such as the strenuous physical demand, sympathetic nervous system activation, increased thermal burden, and the environmental exposure to smoke pollutants. Characterizing the impact of varying thermal burden and pollutant exposure on hemodynamics may help understand the CV burden experienced during firefighting. The purpose of this study was to examine the hemodynamic response of firefighters to training environments created by pallets and straw; oriented strand board (OSB); or simulated fire/smoke (fog). Twenty-three firefighters had brachial blood pressure measured and central blood pressure and hemodynamics estimated from the pressure waveform at baseline, and immediately and 30 minutes after each scenario. The training environment did not influence the hemodynamic response over time (interaction, p > 0.05); however, OSB scenarios resulted in higher pulse wave velocity and blood pressure (environment, p < 0.05). In conclusion, conducting OSB training scenarios appears to create the largest arterial burden in firefighters compared to other scenarios in this study. Environmental thermal burden in combination with the strenuous exercise, and psychological and environmental stress placed on firefighters should be considered when designing fire training scenarios and evaluating CV risk.

Similar Effects of Acute Resistance Exercise on Carotid Stiffness in Males and Females.

Sex differences exist in vascular responses to blood pressure perturbations, such as resistance exercise. Increases in aortic stiffness following acute resistance exercise appear different between sexes, with attenuated increases in females vs. males. Whether sex differences exist in carotid stiffness, following resistance exercise is unknown. This study sought to examine sex differences in carotid stiffness, aortic stiffness, and hemodynamics following acute resistance exercise. Thirty-five participants (18 male) completed 3 sets of 10 repetitions of maximal isokinetic knee extension/flexion. Aortic stiffness and hemodynamics were estimated using an automated oscillometric blood pressure monitor at baseline, 5- and 30-min post-exercise. Carotid stiffness was assessed by ß-stiffness index, pressure-strain elastic modulus and arterial compliance using ultrasonography. Resistance exercise increased aortic stiffness, mean and systolic pressure at 5-min (p<0.01), and pressure-strain elastic modulus at 5-min in both sexes (p<0.05). Arterial compliance decreased at 5- and 30-min post exercise in both sexes (p<0.01). No interaction effects were detected in carotid stiffness, aortic stiffness, and hemodynamics, indicating similar vascular responses between sexes. Our findings indicate that the large arteries appear to stiffen similarly following resistance exercise in males and females when presented with similar blood pressure responses.

Sex Differences in Aortic Hemodynamics Following Acute Exercise: Wave Separation Analysis.

The importance of sex differences in the control of blood pressure responses to exercise is controversial. It is unknown whether the potential sex differences are a result of magnitude differences in forward or reflected pressure waves. The purpose of this study was to investigate sex differences in BP following acute exercise using wave separation analysis. Sixty-eight adults (36 females) participated in the study. Aerobic capacity was measured during a graded cycle ergometry test. Central pulse wave analysis was derived from the radial pulse using applanation tonometry and separated into forward and reflected pressure waves before, and 15 min and 30 min after maximum aerobic exercise. Both males and females exhibited significantly decreased brachial SBP (p<0.05) following acute exercise. However, only males exhibited a significant decrease in forward wave pressure (p<0.05). Reflected wave pressure was decreased following exercise in both sex (p<0.05) with no sex difference. Males and females differ in blood pressure control following maximal exercise. Results show that males rely on both central and peripheral hemodynamic modifications, whereas females mostly rely on peripheral modifications. The preferential peripheral adaptations in females may provide insight regarding mechanisms of blood pressure control and the disproportionate development of hypertension in young men compared to women.

Cognitive Enhancement Strategies for Older Adults: An Evaluation of Different Training Modalities to Improve Executive Function-A Systematic Review and Meta-Analysis.

(1) Background: The aging population is expected to triple by 2050. Executive functions decline with age, impacting daily tasks, and this is associated with neurodegenerative diseases. Aerobic and resistance exercises positively affect cognitive function in older adults by influencing growth markers. However, the modalities of exercise and the optimal parameters for maximum cognitive benefits remain unclear. (2) Methods: A meta-analysis of randomized clinical trials (RCTs) was conducted. The systematic search was on slowing cognitive decline and performed in the PubMed/MEDLINE and Cochrane Library databases. Articles were included if participants were ≥65 years, healthy, and performing resistance or aerobic exercise, and they were excluded if there was a combination of training and if they have neurological disease or cognitive impairment. (3) Results: The search strategy found a total of 1635 studies. After removing duplicates and assessing the inclusion and exclusion criteria, eight articles were included in the meta-analysis, with a total of 463 healthy older adults analyzed. No significant differences between the intervention groups and the control groups after the aerobic or resistance programs were found. (4) Conclusions: Aerobic exercise interventions improved executive function more than resistance training in older adults, but without statistically significant differences. This can serve as a guide to see, with caution, whether we need a multidisciplinary approach to be more effective in improving the cortical health of older adults.

Home-based exercise improves subclinical atherosclerosis marker in multiple sclerosis.

PURPOSE: Using a 12-week, randomized controlled trial coupled with social cognitive theory behavioral coaching, we aimed to assess the effect of a home-based aerobic training intervention versus an attention-control on aerobic fitness, subclinical atherosclerosis, and mobility in persons with MS. METHODS: Persons with MS with an expanded disability status scale score between 0 and 4 were randomized to a 12-week aerobic exercise (EX) (n = 26; 19 females; 49 yrs; 28.8 kg/m2) or attention-control (CON) condition (stretching; n = 22; 16 females; 44 yrs; 29.2 kg/m2). Aerobic capacity was assessed via a graded cycle ergometry test with indirect calorimetry. The co-primary measures of subclinical atherosclerosis assessed included carotid intima media thickness, a test of vasodilatory reactivity, and arterial stiffness. Mobility was assessed via a timed 25-foot walk test (T25FW) and a 6 min walk test. The EX group engaged in cycle ergometry 3d/wk with gradual increases in the intensity and duration of the exercise sessions. CON participated in standardized stretching designed to provide the same contact time as EX 3d/wk. Behavioral coaching took place via weekly phone/video chats to track adherence. RESULTS: Aerobic capacity, vasodilatory reactivity, and T25FW speed increased only in the EX group, 7%, 16%, and 13% (p<0.05), respectively; whereas the CON group did not change. CONCLUSION: The EX group had modest, yet significant, increases in aerobic capacity over the 12-week period, coupled with improvements in T25FW speed and vasodilatory reactivity. A home-based exercise intervention can improve outcomes of a subclinical marker of atherosclerosis, which provides a basis for examining these outcomes in persons prescreened for CVD-related comorbidities and/or mobility issues.

Central and Peripheral Postexercise Blood Pressure and Vascular Responses in Young Adults with Obesity.

INTRODUCTION: Adults with obesity are at an increased risk of incident hypertension. Regular aerobic exercise is recommended for the prevention and treatment of hypertension, but whether young adults with obesity exhibit impaired postexercise blood pressure (BP) and vascular responses remains unclear. PURPOSE: We tested the hypothesis that young adults with obesity exhibit attenuated postexercise hypotension (PEH) and postexercise peripheral vasodilation compared with young adults without obesity. METHODS: Thirty-six normotensive adults without and with obesity (11 men and 7 women per group) underwent measurements of brachial and central BP, and leg blood flow (Doppler ultrasound) at baseline and at 30, 60, and 90 min after acute 1-h moderate-intensity cycling. Leg vascular conductance (LVC) was calculated as flow/mean arterial pressure. RESULTS: Both groups exhibited similar brachial and central PEH (peak change from baseline, -2 and -4 mm Hg for brachial and central systolic BPs, respectively, for both groups; time effect, P < 0.05). Both groups also exhibited postexercise peripheral vasodilation, assessed via LVC (time effect, P < 0.05), but its overall magnitude was smaller in young adults with obesity (LVC change from baseline, +47% ± 37%, +29% ± 36%, and +20% ± 29%) compared with young adults without obesity (LVC change from baseline, +88% ± 58%, +59% ± 54%, and +42% ± 51%; group effect, P < 0.05). CONCLUSIONS: Although obesity did not impair PEH after acute moderate-intensity exercise, young adults with obesity exhibited smaller postexercise peripheral vasodilation compared with young adults without obesity. Collectively, these findings have identified evidence for obesity-induced alterations in the peripheral vasculature after exercise.

Aging reduces cerebral blood flow regulation following an acute hypertensive stimulus.

Aging increases arterial stiffness, which has a negative impact on cerebral blood flow (CBF) regulation (decreases CBF and increases CBF pulsatility). The association between arterial stiffness and CBF pulsatility may, in part, explain the relationship between elevated blood pressure (BP) fluctuations and end-organ disease with aging. To understand the mechanisms by which large BP alterations influence cerebral blood flow regulation in both young and old, we examined the effects of age on central and cerebral blood flow regulation following an acute hypertensive stimulus [resistance-exercise (RE)]. Measurements were obtained pre and immediately, 5, and 30 min post-RE in young (n = 35) and older (n = 26) adults. Measurements included cerebral blood velocity (CBv), CBv pulsatility, central pulse-wave velocity (PWV), beta-stiffness index (ß), and carotid blood flow pulsatility. Central hemodynamics and BP were continuously recorded. Mean CBv increased immediately post-RE only in the young and decreased below baseline at 5 min post-RE in both groups (interaction, P < 0.05). Older adults had a greater increase in CBv pulsatility immediately post-RE compared with the young (interaction, P < 0.05). Mean BP was higher and carotid pulsatility was lower in the older group and increased immediately post-RE in both groups (P < 0.05). PWV increased immediately post-RE (P < 0.05). There were no changes in ß. In conclusion, with aging, greater central arterial stiffness leads to a greater transmission of pulsatile blood velocity from the systemic circulation to the cerebral circulation following an acute hypertensive stress.NEW & NOTEWORTHY Reductions in cerebral blood flow and increases in flow pulsatility with aging are associated to cerebrovascular disease; however, little is known about how an acute hypertensive stimulus effects cerebral blood flow regulation in an aged population. Following the hypertensive stimulus, older adults elicit an attenuated increase in cerebral blood velocity and greater transmission of pulsatile velocity to the brain compared with young adults, demonstrating reduced cerebral blood flow regulation to elevated blood pressure responses with aging.

Peripheral blood flow regulation in response to sympathetic stimulation in individuals with Down syndrome.

BACKGROUND: Individuals with Down syndrome (DS) experience autonomic dysfunction, with reduced sympathetic and parasympathetic control. This results in alterations in resting heart rate and blood pressure and attenuated responses to sympathoexcitatory stimuli. It is unknown to what extent this impacts the regulation of peripheral blood flow in response to sympathetic stimuli, which is an important prerequisite to exercise and perform work. Therefore, we aimed to investigate differences in peripheral blood flow regulation in response to lower body negative pressure (LBNP) between individuals with and without DS. METHODS: Participants (n=10 males with DS and n=11 male controls, mean age 23.7 years ± 3.2) underwent 5 min of LBNP stimulations (-20 mmHg), after resting supine for 10 min. One minute steady state blood pressure and blood flow at baseline and during LBNP were obtained for analysis. Mean flow velocity and arterial diameters were recorded with ultrasonography; foreram blood flow (FBF), shear rate and forearm vascular conductance (FVC) were calculated using brachial blood pressure measured right before ultrasound recordings. RESULTS: Participants with DS responded differently (consistent with reduced vasoconstrictive control) to the LBNP stimulus (significant ConditionxGroup interaction effect) for mean velocity (p=0.02), FBF (p=0.04), shear rate (p=0.02) and FVC (p=0.03), compared to participants without DS. CONCLUSION: Young males with DS exhibit reduced peripheral regulation of blood flow in response to LBNP compared to controls, indicating a blunted sympathetic control of blood flow. Further research is necessary to explore the impact of these findings on exercise and work capacity.

Healthy aging and carotid performance: strain measures and ß-stiffness index.

Arterial stiffness is related to the risk of cardiovascular disease (CVD) and increases with aging. Functional impairment of the arterial wall can occur before structural changes and can be detectable before CVD symptoms. The elastic properties of the carotid arterial wall during the cardiac cycle can be evaluated by standard 2-dimensional (2D) ultrasound longitudinal or circumferential imaging of vascular deformation (strain) using speckle tracking. The purpose of this study was to compare standard 2D ultrasound circumferential and longitudinal images of vascular tissue motion and strain using speckle tracking in young and older individuals. Participants underwent recording of 2D ultrasound circumferential and longitudinal images of the common carotid artery. Circumferential carotid strain (CS) and CS rate were obtained and analyzed via speckle tracking software. Following the strain analysis, the circumferential strain ß-stiffness (C-ß) was calculated. Conventional longitudinal ß-stiffness (L-ß) was calculated and non-invasive blood pressure measurements were obtained from carotid artery pressure measurements in a resting supine position using applanation tonometry. C-ß was significantly higher than L-ß, and the association with age was greater (r = .824 vs. r = .547). CS and CS rate were significantly higher in the young compared to the older group. L-ß does not explain as much of the age-dependent differences in the carotid artery compared with C-ß. This is possibly due to the inclusion of whole arterial wall motion and deformation observed in the CS image. The ability of C-ß to accurately predict the future risk of CVD independent of age still needs further investigation.

Impact of obesity and Down syndrome on peak heart rate and aerobic capacity in youth and adults.

Individuals with Down syndrome (DS) exhibit reduced aerobic capacity with reduced peak heart rate (HRpeak). This condition is often coexistent with higher level of obesity compared to individuals without DS. The purpose of this study is to investigate the effects of obesity and Down syndrome (DS) on peak heart rate (HRpeak) and peak oxygen consumption (VO2peak) in children and adults both with and without intellectual disabilities (ID)s. VO2peak and HRpeak from individualized treadmill tests on 654 individuals were analyzed. Body mass index was used to categorize individuals' weight status using standard cut-offs. DS groups had the lowest HRpeak (167bpm±14, p<0.05) compared to individuals with (183bpm±12) without ID (187bpm±12). Obesity did not affect HRpeak among adults and children with DS. VO2peak was lower among individuals with DS (25.2mL/kg/min±6.3, p<0.05) when compared individuals with (37.0mL/kg/min±10.5) and without ID (36.1mL/kg/min±10.4). Obese adults with DS had lower VO2peak (24.3mL/kg/min±6.9, p=0.001) compared to the normal weight (26.7±7.1mL/kg/min) and overweight groups (27.0mL/kg/min±6.1) with DS. Conversely, in children, obesity level did not impact VO2peak in individuals with DS. Our results suggest that DS attenuates both VO2peak and HRpeak, regardless of obesity status and age group. However, obesity was associated with lower VO2peak in all adults, but not in children with DS.

Effects of combined aerobic and resistance exercise on central arterial stiffness and gait velocity in patients with chronic poststroke hemiparesis.

OBJECTIVE: The effects of combined aerobic and resistance exercise training on central arterial stiffness and gait velocity in patients with chronic poststroke hemiparesis were investigated. DESIGN: Twenty-six patients with chronic poststroke hemiparesis were randomly assigned to either the combined aerobic and resistance exercise group (n = 14) or the control group (n = 12). The exercise intervention group received a combined aerobic and resistance exercise training (1 hr/day, three times/week for 16 wks), whereas the control group received usual care. Central arterial stiffness was determined by pulse wave velocity and augmentation index. Gait velocity was assessed using the 6-min walk test, 10-m walk test, and the Timed Up-and-Go test. RESULTS: Patients in the exercise intervention group had greater improvement of mean pulse wave velocity (P < 0.001), augmentation index (P = 0.048), and gait velocity (6-min walk test, P < 0.001; 10-m walk test, P < 0.001) than did patients in the control group. Patients in the exercise intervention group also had greater improvements in physical fitness component (grip strength, P < 0.001; muscular strength of upper and lower limbs, P < 0.027; flexibility, P < 0.001) when compared with control patients. CONCLUSIONS: The combined aerobic and resistance exercise program significantly reduced central arterial stiffness and increased gait velocity in patients with chronic poststroke hemiparesis.

Aerobic exercise and postprandial lipemia in men with the metabolic syndrome.

INTRODUCTION: It is currently unclear as to how exercise prescription variables influence attenuations of postprandial lipemia (PPL) in men with the metabolic syndrome (MetS) after exercise. Therefore, the purposes of this investigation were to compare the effects of low- and moderate-intensity exercise and accumulated versus continuous exercise on PPL in males with MetS. METHODS: Fourteen males with MetS (waist circumference (WC) = 110.2 +/- 10.9 cm; triglycerides (TG) = 217 +/- 84 mg dL(-1); fasting blood glucose = 105 +/- 7 mg dL(-1); high-density lipoprotein cholesterol (HDL-C) = 44 +/- 7 mg dL(-1); systolic blood pressure (SBP) = 120 +/- 12 mm Hg; diastolic blood pressure (DBP) = 76 +/- 10 mm Hg) completed a control condition consisting of a high-fat meal and blood sampling at 2 h intervals for 6 h. Next, participants completed the following exercise conditions: 1) continuous moderate-intensity (MOD-1), 2) continuous low-intensity (LOW-1), and 3) two accumulated moderate-intensity sessions (MOD-2). The test meal and blood sampling were repeated 12-14 h after exercise. Area under the curve (AUC) scores and temporal postprandial responses were analyzed using repeated-measures ANOVA for TG and insulin. RESULTS: The TG AUC decreased by 27% after LOW-1. TG concentrations were also reduced by 22% and 21% at 4 h postmeal after LOW-1 and MOD-1, yet TG parameters were no different from the control condition after MOD-2 (P < 0.05 for all). CONCLUSION: These findings indicate that 500 kcal of continuous aerobic exercise before a meal attenuates PPL in men with MetS. This outcome can be achieved through low- or moderate-intensity exercise performed in a single session. Accumulating moderate-intensity exercise does not appear to effectively modulate PPL in men with MetS.