Impact Of Aerobic Fitness Research Articles

The Impact Of Aerobic Fitness On Isometric Handgrip-Mediated Assessment Of Sympathetic Transduction

The Impact Of Aerobic Fitness On Isometric Handgrip-Mediated Assessment Of Sympathetic Transduction

What is the impact of aerobic fitness and movement interventions on low-flow-mediated vasoconstriction? A systematic review of observational and intervention studies.

The cardiovascular benefits of physical exercise are well established. The vasoreactivity that occurs during reductions in local arterial blood flow, termed low-flow-mediated constriction (L-FMC), is a measure of endothelial-dependent vasoconstrictor function. It is unclear whether aerobic fitness and movement (or lack thereof) influences L-FMC. We systematically reviewed studies examining the impact of physical behaviours on L-FMC. To be included, cross-sectional and interventional studies had to examine the impact of a physical behaviour on L-FMC in adults. There were no language or date of publication restrictions. Sources were searched in May, 2021 and included Scopus, Embase, MEDLINE, CINAHL, and Academic Search Premier. National Institutes of Health quality assessment tools were used. Fourteen studies (15 arms; 313 participants; 398 total observations from four arteries) met the inclusion criteria. The study quality varied from four out of 14 (controlled intervention scoring) to nine out of 12 (longitudinal intervention with no control group scoring) with the total points dependent upon the study design. Conflicting results were reported for acute prolonged sitting studies (attenuated L-FMC: n = 1; no change: n = 1) and resistance exercise (increased L-FMC: n = 2; no change: n = 2). Most observational studies examining aerobic fitness (3/4 studies) and aerobic exercise interventions (4/5 studies) observed a favourable effect on L-FMC. Overall, the included studies support that higher aerobic fitness and engaging in aerobic exercise training may augment L-FMC responses. Our systematic review highlights the heterogeneity between studies and identifies current gaps and future directions to better our understanding of (in)activity, exercise, and posture on endothelial vasoconstrictor function. PROSPERO Registration No.: CRD42021248241.

Greater Influence of Aerobic Fitness on Autonomic Support of Blood Pressure in Young Women Than in Older Women.

Aging increases autonomic support of blood pressure; however, the impact of aerobic fitness on autonomic support of blood pressure has not been addressed in women. As such, we hypothesized that aerobic fitness would be related to the change in blood pressure during ganglionic blockade such that women with greater aerobic fitness would have a blunted fall in blood pressure during ganglionic blockade due to increased vagal tone. Thirteen young premenopausal and 13 older postmenopausal women completed a screening visit where aerobic fitness (maximal oxygen consumption, VO2max) was measured. On a separate study day, participants were instrumented for assessment of muscle sympathetic nerve activity, heart rate (electrocardiography), and beat by beat blood pressure (arterial catheter and pressure transducer) and underwent pharmacological blockade of the autonomic ganglia using trimethaphan camyslate. Heart rate, blood pressure, and muscle sympathetic nerve activity were analyzed before and during ganglionic blockade. In young women, there was a significant relationship between aerobic fitness and the change in blood pressure during ganglionic blockade (r=0.761, P=0.003). In older women, there was no relationship between aerobic fitness and the change in blood pressure during ganglionic blockade (r=-0.106, P=0.73). Measures of heart rate variability were related to fitness in young women, but not older women (root mean square of successive differences between normal heartbeats, r=0.713, P=0.006 versus r=-0.172, P=0.575). Our data suggest that in young women, autonomic support of blood pressure is attenuated in those that are highly fit; however, this relationship is not significant in older women.

The impact of aerobic fitness on arterial stiffness and adrenal cortex hormones in middle-aged and older adults.

An increase in arterial stiffness with advance aging is a risk for cardiovascular disease. Cardiovascular dysfunction is associated with the imbalance of adrenal cortex hormones, especially with the cortisol/dehydroepiandrosterone sulfate (DHEAs) ratio. However, the impact of aerobic fitness on arterial stiffness and cortisol/DHEAs ratio is unclear. The aim of this study was to investigate the relationship between aerobic fitness, arterial stiffness, and cortisol/DHEAs ratio. A total of 198 middle-aged and older adults (aged 50-79 years old) participated in this study. The aerobic fitness evaluated by peak oxygen consumption (VO2peak), carotid-femoral pulse wave velocity (cfPWV) as an indicator of arterial stiffness, and serum cortisol and DHEAs and their ratio were measured. The subjects were divided into the lower (n = 100) and the higher (n = 98) aerobic fitness groups based on the median value of VO2peak. There were no significant differences in serum cortisol and DHEAs concentration alone between the lower and higher fitness groups. However, the cortisol/DEHAs ratio and cfPWV in the higher fitness group was smaller than in the lower fitness group (p < 0.05). The cortisol/DHEAs ratio was significantly correlated with cfPWV (r = 0.159, p < 0.05). These findings suggest that the cortisol/DHEAs ratio is associated with aerobic fitness and arterial stiffness in middle-aged and older adults.

Relationship between brachial and popliteal artery low-flow-mediated constriction in older adults: impact of aerobic fitness on vascular endothelial function.

We previously observed that brachial artery (BA) low-flow-mediated constriction (L-FMC) is inversely related to aerobic fitness (i.e., V̇o2peak) in older adults (OA). However, it is unclear if an L-FMC response is elicited in the popliteal artery (POP) or if a similar inverse relationship with aerobic fitness exists. Considering that the POP experiences larger shear stress fluctuations during sedentary behaviors and traditional lower limb modes of aerobic exercise, we tested the hypotheses that 1) heterogeneous L-FMC responses exist between the BA versus POP of OA, and 2) that aerobic fitness will be inversely related to POP L-FMC. L-FMC was assessed in 47 healthy OA (30 women, 67 ± 5 yr) using duplex ultrasonography and quantified as the percent decrease in diameter (from baseline) during the last 30 s of a 5-min distal cuff occlusion period. When allometrically scaled to baseline diameter, the BA exhibited a greater L-FMC response than the POP (-1.3 ± 1.6 vs. -0.4 ± 1.6%; P = 0.03). Furthermore, L-FMC responses in the BA and POP were not correlated (r = 0.22; P = 0.14). V̇o2peak was strongly correlated to POP L-FMC (r = -0.73; P < 0.001). The heterogeneous BA versus POP L-FMC data indicate that upper limb L-FMC responses do not represent a systemic measure of endothelial-dependent vasoconstrictor capacity in OA. The strong association between V̇o2peak and POP L-FMC suggests that localized shear stress patterns, perhaps induced by lower limb dominant modes of aerobic exercise, may result in greater vasoconstrictor responsiveness in healthy OA. NEW & NOTEWORTHY We compared low-flow-mediated constriction responses between the brachial and popliteal arteries of healthy older adults. Vasoconstrictor responses were not correlated between arteries. A strong relationship between aerobic fitness and low-flow-mediated vasoconstriction was observed in the popliteal artery. These findings suggest that brachial vasoconstrictor responsiveness is not reflective of the popliteal artery, which is exposed to larger shear stress fluctuations during bouts of sedentary behavior and traditional lower limb modes of exercise.

Impact of aerobic fitness on cerebral blood flow and cerebral vascular responsiveness to CO2 in young and older men.

We sought to test the hypothesis that brain blood flow and cerebral vascular responsiveness to carbon dioxide (CVRCO2 ) are greater in aerobically trained young and old individuals compared to their untrained counterparts. In 11 young trained {[23 (20-26) years] [mean (95% confidence interval)]}, 10 young untrained [25 (22-28) years], 8 older trained [65 (61-69) years], and 9 older untrained [67 (64-71) years] healthy individuals, Doppler ultrasound of the internal carotid (ICA) and vertebral (VA) artery blood flow were determined, along with middle cerebral artery mean flow velocity (MCA Vmean ). Bilateral ICA blood flow was higher in trained individuals when compared to untrained (≈31%, P<0.05), but was not influenced by age. VA blood flow was not affected by age or cardiorespiratory fitness. MCA Vmean was reduced with age [59.5 (55.0-64.1) cm/s young vs 43.6 (38.4-48.9) cm/s old, P<0.05] with no significant effect of training observed. MCA CVRCO2 were not significantly affected by either age or training status, while ICA CVRCO2 tended to be elevated in the old trained group. These findings indicate that endurance training enhances bilateral ICA but not VA blood flow in both young and older individuals.

Impact of aerobic fitness on musculoskeletal sickness absence 5–15 years later: a cohort study of 227 201 male Norwegian employees

ObjectivesThe aim of the study was to estimate associations between aerobic fitness among men at age 18–19 years and work absence due to musculoskeletal sickness 5–15 years later.MethodsAll 321 975...

Impact of Aerobic Fitness on Cerebral White Matter Integrity in the Cingulum.

Aerobic fitness may help maintain cognitive function in older adults. However, little is known about the potential mechanisms by which improvements in aerobic fitness may lead to these changes. One potential mechanism is cerebral white matter integrity (CWMI). Both CWMI and aerobic fitness decline with aging. Hence, different aerobic fitness levels may be related to varying amounts of CWMI, which then could impact cognitive function. PURPOSE: To determine brain regions with significant positive associations between CWMI and aerobic fitness in older adults. METHODS: 15 older adults (66 + 6 yrs) completed peak VO2 treadmill testing (Modified Pepper Protocol; VO2 peak range = 14 to 54 ml/kg/min). Magnetic resonance (MR) imaging was used to analyze multiple brain regions during rest on a separate day. Structural 3D T1 MP-Rage and diffusion tensor imaging (DTI, 21 directions, repeated 4x) was done using a 3.0 Tesla MR imaging unit. 3D fractional anisotropy (FA) maps were computed from the raw DTI data. Previous research has shown age-related FA declines in the frontal regions, therefore the specific regions of interest (ROI) identified for this study were the cingulum, genu of the corpus callosum, and uncinate fasciculus (UNC). All ROIs were outlined using InsightSNAP software on the FA maps (FA Coefficient of Variance = 3.9%). RESULTS: Manova revealed no significant age and gender effects. Bivariate analysis showed an overall positive correlation between FA and VO2 peak for the entire cingulum (r = 0.536: p = 0.032). A multiple regression analysis indicated varying contributions of VO2peak on the FA within specific segments of the cingulum (anterior: R2 = 0.32, p = 0.014; medial: R2 = 0.18, p = 0.056; posterior: R2 = 0.04, p = 0.25). Analyses of specific segments within the left and right cingulum resulted in significant correlations between FA and VO2peak in the left anterior (r = 0.559, p = 0.030) and left medial (r = 0.572, p = 0.026) segments. Multiple regression revealed that the greatest unique contribution of VO2peak to the FA variance resided in the medial segment of the left cingulum (R2 = 0.33, p = 0.026 ). Genu and UNC results: r < 0.48; R2 < 0.23, p > 0.07. CONCLUSIONS: There are segment and side-specific positive associations between CWMI and aerobic fitness in the cingulum. Funding: Biomedical Research Imaging Center, UNC-CH.

Effect of Cardiorespiratory Fitness on Cortisol and Cardiorespiratory Responses to Concurrent Mental and Physical Stress

Aerobic fitness is associated with increased sensitivity to mental challenge, evidenced by a relative elevation in heart rate (HR) response, and enhanced efficiency, demonstrated by a relative attenuation in absolute HR. However, the impact of aerobic fitness on cardiorespiratory and hypothalamic pituitary adrenal (HPA) activation in responses to mental challenge during exercise has not been investigated. PURPOSE: This study compared cortisol (CORT) and cardiorespiratory responses between individuals with below average fitness (VO2max = 34.29 ± 0.99 ml/kg/min-1) and individuals with above average fitness (VO2max = 48.04 ± 1.60 ml/kg/min-1). METHODS: Forty-eight apparently healthy individuals (24 high fit [HF] and 24 low fit [LF]) participated in two counter-balanced experimental conditions. In one condition, the participant was mentally challenged while exercising on a cycle ergometer at 60% of VO2max (dual-stress condition; DSC) and the other in which the participant exercised at the same intensity without the mental challenge (exercise-alone condition; EAC). State anxiety measures and the NASA Task Load Index (NTLX) were used to assess perceived mental and physical workload during each condition. RESULTS: State anxiety and NTLX scores were elevated in the DSC. The DSC also elicited greater elevations in HR, respiration rate, ventilation, ventilatory efficiency and CORT values. Additionally, HF individuals demonstrated significantly lower CORT levels (HF = 11.59 ± 0.83 nmol/L; LF = 15.17 ± 0.55 nmol/L; p = .01) in the DSC following the conclusion of the mental challenge. CONCLUSIONS: These results suggest that a mental challenge during a physical challenge impacts the cardiorespiratory system and activates the HPA axis, and that increased fitness levels may attenuate these effects.