Vascular and Cardiac response to acute aerobic exercise
Vascular responses to acute aerobic exercise
The heart produces enough cardiac output to meet basal metabolic needs at rest, and the central cardiovascular reflexes act to keep blood pressure within acceptable limits. The resistance arteries within each tissue determine regional peripheral resistance to provide appropriate blood supply to meet the body's metabolic demands. The diameter of the resistance arteries, which is controlled by the level of contraction of the vascular smooth muscle (VSM) surrounding the arteries, determines vascular resistance. These arteries are regulated by central control signals of SNS and local chemical and mechanical variables. As a result, VSM in these resistance arteries acts as an integrator of these various factors (Whyte et al., 2018). Whyte et al. explain the muscular requirement for nutrients and oxygen increases when muscle contractions drive physical activity. Within the skeletal muscle, vascular control mechanisms provide a nearly linear increase in blood flow, which, together with alterations in oxygen extraction, matches the increase in oxygen consumption of the muscle. Central control systems allow for a near-linear increase in heart rate and cardiac output, which is also matched to muscle tissue oxygen use (p.2, 2018). When SNS takes over, a more significant proportion of blood flow is directed towards the skin and skeletal muscles than when PNS is in charge. As a result, blood flow increases to the highly active tissues during exercise while decreasing to the less active tissues. The body prioritizes blood flow to its tissues based on their needs in this way.
Cardiac responses to acute aerobic exercise
Heart rate variability (HRV) measures the difference in time between each heartbeat. It indicates the ability of autonomic cardiac regulation to respond to various physiological stimuli, including metabolic and mechanical changes. The interaction between inputs passing through afferent pathways (towards the heart) and reactions to efferent (away from the heart) pathways causes this process. Kleiger et al. found a substantial link between mortality risk and decreased autonomic cardiac regulation in patients with acute myocardial infarction (1987). On the other hand, physical activity can be utilized as a non-pharmacological technique to minimize the risks. Thus, the purpose of the Gambassi et al. study was to look into the acute effects of aerobic exercise on autonomic cardiac regulation (2019). Exercise has been shown to provide heart-health benefits. Exercise boosts cardiac output and blood pressure in the short term, but people who have adapted to exercise have a lower resting heart rate and less cardiac hypertrophy. Alterations in tissue metabolism and signaling have been related to cardiac and vascular changes (Nystoriak et al., 2018). The heart rate (HR) and stroke volume (SV) rise in response to exercise, and both mechanisms are controlled by the neurological and endocrine systems. As the intensity of the activity increases, so does bodily oxygen consumption (VO2), increasing cardiac output. Acute aerobic exercise raises cardiac output to meet the tissues' increased blood and oxygen requirements. Neural activation of the heart plays a vital role in the cardiac response. Both sympathetic (SNS) and parasympathetic (PNS) systems control the heart's activity. As the intensity rises, the PNS becomes less active, and the SNS controls the circulatory system. The rate of respiration and the heart rate both increase due to this stimulation. Muscle contractions gradually affect chemo and mechanoreceptors, causing the HR to rise. As exercise intensity increases, chemical and mechanical receptors relay their information to control centers: muscle stretching and cell metabolism controlled by mechanoreceptors and chemoreceptors, respectively.
dos Santos, Asano, R. Y., Filho, I. G., Lopes, N. L., Panelli, P., Nascimento, D. da C., Collier, S. R., & Prestes, J. (2014). Acute and Chronic Cardiovascular Response to 16 Weeks of Combined Eccentric or Traditional Resistance and Aerobic Training in Elderly Hypertensive Women: A Randomized Controlled Trial. Journal of Strength and Conditioning Research, 28(11), 3073–3084. https://doi.org/10.1519/JSC.0000000000000537
Gambassi, Almeida, F. de J. F., Almeida, A. E. A. F., Ribeiro, D. A. F., Gomes, R. S. A., Chaves, L. F. C., Sousa, T. M. da S., & Nina, V. J. da S. (2019). Acute Response to Aerobic Exercise on Autonomic Cardiac Control of Patients in Phase III of a Cardiovascular Rehabilitation Program Following Coronary Artery Bypass Grafting. Revista Brasileira de Cirurgia Cardiovascular, 34(3), 305–310. https://doi.org/10.21470/1678-9741-2019-0030
Kleiger RE,MillerJP,BiggerJT,MossAJ.Decreasedheartratevariabilityand its association with increased mortality after acute myocardial infarction. Am J Cardiol. 1987;59(4):256-62. doi:10.1016/0002-9149(87)90795-8.
Nystoriak, M. A., & Bhatnagar, A. (2018). Cardiovascular Effects and Benefits of Exercise. Frontiers in cardiovascular medicine, 5, 135. https://doi.org/10.3389/fcvm.2018.00135
Whyte, J. J., & Laughlin, M. H. (2010). The effects of acute and chronic exercise on the vasculature. Acta physiologica (Oxford, England), 199(4), 441–450. https://doi.org/10.1111/j.1748-1716.2010.02127.x
