Introdução. A prática regular do exercício de força (EF) está associada a adaptações metabólicas, neuromusculares e cardiovasculares que repercutem de maneira positiva sobre a saúde e qualidade de vida de seus praticantes. No entanto, Indivíduos sedentários apresentam comprometimentos agudos na função endotelial após EF de alta intensidade. Objetivo. Avaliar a função endotelial de indivíduos sedentários de meia idade em resposta a diferentes intensidades do EF. Métodos. 11 indivíduos sedentários (40,1±3,9 anos; 27,3±1,4 kg/m2) realizaram EF em três condições experimentais: extensão de joelhos a 50% de 1RM (MI), 80% de 1RM (AI) e repouso na condição controle (CON). Foi realizada avaliação da vasodilatação mediada pelo fluxo (FMD) antes, 30 minutos após e 60 minutos após os protocolos. A quantificação das concentrações de NO2 e NO3 (NOx), endotelina-1 (ET-1) e TBARS foram realizadas antes, imediatamente após e 60 minutos após os protocolos. A pressão arterial foi mensurada antes e após os protocolos Resultados. A FMD aumentou significativamente 30 minutos após o exercício na condição MI (12,5± 4,10 para 17,2±3,9 %; p=0,01) bem como os níveis de NOx (6,8± 3,3 vs. 12,6± 4,2μM; p= 0,007). A concentração de ET-1 aumentou imediatamente após na condição AI (20,02±2,2 vs. 25,4± 2,1pg/ml; p= 0,004). A elevação da pressão arterial não diferiu entre as condições MI e AI. As concentrações de TBARS não se alteraram ao longo dos protocolos. Conclusão. O EF de moderada intensidade aumenta a FMD e os níveis NOx após uma sessão aguda de exercício em indivíduos sedentários de meia idade, estes resultados sugerem que menores intensidades do EF são mais seguras ao iniciar um programa de exercícios. / Regular resistance exercise (RE) is associated with metabolic, neuromuscular and cardiovascular adaptation that results in improvement of quality of life and health. However, sedentary subjects have been showing an acute impairment on endothelial function after high intensity resistance exercise. The aim of this study was to evaluate the endothelial function in sedentary middle age men after RE in different intensities. Methods. Eleven middle age sedentary men (40,1±3,9 years; 27,3±1,4 kg/m2) performed RE in three different conditions: knee extension at 50% of one 1RM (MI), at 80% of 1RM (HI) and rest in the control group (CON). Flow mediated dilation (FMD) was assessed before, 30 and 60 minutes of exercise. Venus plasma concentration of ET-1 NOx and TBARS were measured before, immediately after and 60 minutes after exercise. Blood pressure was evaluated before and after exercise. Results. There was a significant improvement in FMD 30 minutes after exercise in the MI condition (12,5± 4,10 vs 17,2±3,9%; p= 0,016; p=0,01). The plasma NOx concentration was significant higher immediately after MI (6,8± 3,3 vs. 12,6± 4,2μM; p= 0,007). There was a significant improvement in the plasma ET-1 concentration immediately after HI (20,02±2,2 vs. 25,4± 2,1pg/ml; p= 0,004). There was no significant difference in the BP between the experimental conditions (MI vs HI) and TBARS throughout the experimental conditions. Conclusions. Resistance exercise performed in moderate intensity improve endothelial function in sedentary middle aged men, there results suggest that lower intensities of RE could be safe for this population in the beginning of the exercise programs.

abstract: Cardiovascular disease (CVD) is the number one cause of death in the United States and type 2 diabetes (T2D) and obesity lead to cardiovascular disease. Obese adults are more susceptible to CVD compared to their non-obese counterparts. Exercise training leads to large reductions in the risk of CVD and T2D. Recent evidence suggests high-intensity interval training (HIT) may yield similar or superior benefits in a shorter amount of time compared to traditional continuous exercise training. The purpose of this study was to compare the effects of HIT to continuous (CONT) exercise training for the improvement of endothelial function, glucose control, and visceral adipose tissue. Seventeen obese men (N=9) and women (N=8) were randomized to eight weeks of either HIT (N=9, age=34 years, BMI=37.6 kg/m2) or CONT (N=8, age=34 years, BMI=34.6 kg/m2) exercise 3 days/week for 8 weeks. Endothelial function was assessed via flow-mediated dilation (FMD), glucose control was assessed via continuous glucose monitoring (CGM), and visceral adipose tissue and body composition was measured with an iDXA. Incremental exercise testing was performed at baseline, 4 weeks, and 8 weeks. There were no changes in weight, fat mass, or visceral adipose tissue measured by the iDXA, but there was a significant reduction in body fat that did not differ by group (46±6.3 to 45.4±6.6%, P=0.025). HIT led to a significantly greater improvement in FMD compared to CONT exercise (HIT: 5.1 to 9.0%; CONT: 5.0 to 2.6%, P=0.006). Average 24-hour glucose was not improved over the whole group and there were no group x time interactions for CGM data (HIT: 103.9 to 98.2 mg/dl; CONT: 99.9 to 100.2 mg/dl, P>0.05). When statistical analysis included only the subjects who started with an average glucose at baseline > 100 mg/dl, there was a significant improvement in glucose control overall, but no group x time interaction (107.8 to 94.2 mg/dl, P=0.027). Eight weeks of HIT led to superior improvements in endothelial function and similar improvements in glucose control in obese subjects at risk for T2D and CVD. HIT was shown to have comparable or superior health benefits in this obese sample with a 36% lower total exercise time commitment. / Dissertation/Thesis / Ph.D. Exercise and Wellness 2013

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<p><strong>Purpose: </strong>Habitual aerobic exercise improves vascular function; however, the acute vascular response to exercise is poorly understood. The present investigation compared the time course of acute changes in vascular function following two different types of aerobic exercise. <strong>Methods: </strong>Ten untrained males (23 ± 2 yrs) completed one bout of sustained moderate-intensity cycling (END) (30 mins at 55% peak power) or high-intensity interval (HIT) cycling (10 one-minute intervals at 80% peak power) on different days. Endothelium-dependent dilation was assessed by brachial artery flow-mediated dilation (baFMD) at baseline, immediately post-exercise, 1 hour post-exercise and 24 hours post-exercise. Endothelium-independent dilation was assessed via nitroglycerin (NTG) at all time points, except 1 hour post-exercise. <strong>Results:</strong> baFMD values were not significantly different between END and HIT at any time point. Immediately post-exercise baFMD values were unchanged from baseline. 1 Hour post-exercise, relative (p £ 0.001) and absolute (p £ 0.05) baFMD values were attenuated compared to all other time points for both HIT (%FMD baseline: 5.9 ± 2.3%; 1 hour post-exercise: 2.5 ± 1.5%) and END (%FMD baseline: 6.8 ± 2.4%; 1 hour post-exercise: 2.6 ± 1.9%). Relative (p £ 0.05) and absolute (p £ 0.05) NTG responses were attenuated immediately post-exercise compared to baseline for both HIT (%NTG baseline: 18.8 ± 4.4%; immediately post-exercise: 12.3 ± 3.1%) and END (%NTG baseline: 18.3 ± 3.1%; immediately post-exercise: 10.9 ± 4.9%). <strong>Conclusions: </strong>Immediately post-exercise, endothelium-dependent dilation is maintained; but reduced 1 hour following exercise cessation. Similar acute vascular responses are found following HIT and END.</p> / Master of Science in Kinesiology

Endothelial function is influenced by a variety of factors, including shear stress direction and magnitude. Whereas improvements in endothelial function have mostly been attributed to increased anterograde flow, the results of many interventional models in humans suggest that enhancing blood flow in both anterograde and retrograde directions to create a high shear stress oscillatory stimulus may be optimal for improving endothelial function. Well-controlled studies are necessary to further this theory. The purposes of this study were to determine the brachial artery acute shear stress and endothelial function responses to (1) passive heat stress (HEAT), (2) ECG-gated cuff compressions (CUFF), and (3) ECG-gated rhythmic handgrip exercise (HGEX); and (4) to determine if there is a relationship between the degree of shear stress oscillation and endothelial function, regardless of the stimulus applied. We hypothesized that (1) HEAT would increase anterograde shear stress and decrease retrograde shear stress, leading to an unpredictable change in endothelial function; (2) CUFF would increase both anterograde and retrograde shear stress, leading to an increase in endothelial function; (3) HGEX would increase anterograde and retrograde shear stress and exercise metabolites, leading to an increase in endothelial function; and (4) the change in oscillatory shear index would be positively associated with the change in flow-mediated dilation, such that an increment increase in the degree of shear stress oscillation would be accompanied by a proportional improvement in endothelial function. In separate visits, 10 young healthy males (22±3 years) underwent 10 minutes of unilateral HEAT, CUFF, or HGEX on the left arm (EXP), while the right arm served as a within-subject time control (CON). Non-invasive finger plethysmography was used to measure heart rate (HR) and blood pressure (BP) throughout the testing sessions. Ultrasonography was used to obtain measures of blood velocity and arterial diameter from the brachial artery of both limbs throughout the interventions. Anterograde and retrograde shear stress (SS) and oscillatory shear index (OSI) were calculated at baseline and during each intervention to assess the blood flow pattern changes. Endothelial function was assessed before and after each intervention, in both limbs simultaneously using a flow-mediated dilation (FMD) test. HEAT increased HR during the intervention (P < 0.05), mean BP and diastolic BP after the intervention (P < 0.05), anterograde SS in EXP (rest: 15.2 ± 2.9 vs. HEAT: 29.8 ± 8.5 dynes/cm2, P < 0.05), and FMD% in both limbs (P = 0.000). CUFF did not change HR or BP, increased anterograde (rest: 17.9 ± 4.1 vs. CUFF: 43.0 ± 12.4 dynes/cm2, P < 0.05) and retrograde (rest: -3.1 ± 2.5 vs. CUFF: -22.7 ± 6.0 dynes/cm2, P < 0.05) SS in EXP, but did not change FMD% in either limb (P = 0.248). HGEX increased HR during the intervention (P < 0.05), mean BP during and after the intervention (P < 0.05), anterograde SS in EXP (rest: 18.7 ± 5.9 vs. HGEX: 56.4 ± 11.5 dynes/cm2, P < 0.05), and FMD% in both limbs (P = 0.001). These findings suggest that an anterograde-dominant shear stress stimulus may be effective at improving endothelial function, but the confounding effect of sympathetic nervous system activation may play a more dominant role in the acute control response for shorter duration interventions such as the ones explored in this study. / Thesis / Master of Science (MSc) / It has been well established that the pattern of blood flow can impact arterial function, but the nuances of this relationship remain unclear. Through the use of heating, cuff compression, and exercise, this study sought to determine the optimal shear stress pattern to see beneficial changes in arterial function in the arm of young healthy males. Our results show many real life interventions alter not only the shear stress pattern in the artery, but also involve other systems like the brain and muscle that are crucial to maintaining the body’s physiological balance. It is clear that arterial function is regulated through a variety of different mechanisms, and that the changes we observe will depend on the parameters (e.g. duration, intensity, timing of assessment) of the applied stimulus. More specifically, isolating study designs should be constructed to determine the individual contributions of different human body systems to the arterial regulatory response.

Endothelium-dependent vasodilation is an important marker of vascular function. Brachial artery flow-mediated dilation (FMD) is a noninvasive assessment of peripheral artery endothelial function that is associated with coronary artery endothelial function and is an index of cardiovascular health. This thesis sought to investigate factors that may influence the brachial artery FMD response in humans, particularly the sex hormone estrogen and low-volume sprint interval training (SIT). We first demonstrated the intra-individual consistency of the FMD response pattern in healthy young adults and introduced visual data screening as a tool for improving data accuracy. Having established best practices for FMD data analysis, we investigated the brachial artery FMD response in adults with different estrogen profiles: men, premenopausal women with a natural menstrual cycle (NAT), and premenopausal women using combined oral contraceptive pills (OCP). Our findings suggest that estrogen does not augment FMD during high-estrogen phases of a NAT or OCP cycle compared to low-estrogen phases or to men. We also investigated the acute and chronic brachial artery FMD response to a 3x20-s low-volume SIT model. Following a single SIT session, FMD was unchanged in men or women. These findings demonstrate that estrogen does not influence endothelium-dependent dilation at rest or following intense intermittent exercise, but also suggest that low-volume SIT may be an insufficient stimulus for eliciting changes in endothelial function. This stimulus magnitude postulation was further supported by a 12-wk exercise training study, whereby vascular changes were evident following moderate-intensity continuous training but not SIT. Taken together, this work suggests that controlling for menstrual cycle phase and/or OCP use in premenopausal women may not be necessary, making it more feasible to include women as research participants, and highlights the need for future characterization of the minimum low-volume interval stimulus that evokes improvements in endothelial function in healthy young adults. / Thesis / Doctor of Philosophy (PhD) / The endothelium is the inner lining of an artery that separates it from the flowing blood. A healthy endothelium responds to increases in blood flow by producing substances that enable an artery to widen. The projects in this thesis examined whether the responsiveness, and overall function, of the endothelium in healthy young adults is enhanced by the sex hormone estrogen or by “all-out” cycling sprints, an exercise protocol that has gained appeal for its time-efficiency. We demonstrated that estrogen does not enhance endothelial function in women, compared to men, at any phase of a menstrual or birth control pill cycle. A single session or 12-weeks of the intense but brief interval exercise also does not enhance endothelial function. This work suggests it may be easier to include women in future research assessing this measure and that this particular interval exercise protocol may not enhance endothelial function in healthy adults.