This results in an increase in cardiac output to ensure that blood flow to the muscle is matched to the metabolic needs. Both heart rate and stroke volume vary directly with the intensity of the exercise performed and many improvements can be made through continuous training. Another important issue is the regulation of blood flow during exercise. Blood flow must increase in order to provide the working muscle with more oxygenated blood which can be accomplished through neural and chemical regulation. Blood vessels are under sympathetic tone, therefore the release of noradrenaline and adrenaline will cause vasoconstriction of non essential tissues such as the liver, intestines, and kidneys, and decrease neurotransmitter release to the active muscles promoting vasodilatation. Also, chemical factors such as a decrease in oxygen concentration and an increase in carbon dioxide or lactic acid concentration in the blood promote vasodilatation to increase blood flow. As a result of increased vascular resistance, blood pressure rises throughout exercise and stimulates baroreceptors in the carotid arteries and aortic arch. These pressure receptors are important since they regulate arterial blood pressure around an elevated systemic pressure during exercise. Respiratory system adaptationseditAlthough all of the described adaptations in the body to maintain homeostatic balance during exercise are very important, the most essential factor is the involvement of the respiratory system. The respiratory system allows for the proper exchange and transport of gases to and from the lungs while being able to control the ventilation rate through neural and chemical impulses. In addition, the body is able to efficiently use the three energy systems which include the phosphagen system, the glycolytic system, and the oxidative system. Temperature regulationeditIn most cases, as the body is exposed to physical activity, the core temperature of the body tends to rise as heat gain becomes larger than the amount of heat lost. The factors that contribute to heat gain during exercise include anything that stimulate metabolic rate, anything from the external environment that causes heat gain, and the ability of the body to dissipate heat under any given set of circumstances. In response to an increase in core temperature, there are a variety of factors which adapt in order to help restore heat balance. The main physiological response to an increase in body temperature is mediated by the thermal regulatory center located in the hypothalamus of the brain which connects to thermal receptors and effectors. There are numerous thermal effectors including sweat glands, smooth muscles of blood vessels, some endocrine glands, and skeletal muscle. With an increase in the core temperature, the thermal regulatory center will stimulate the arterioles supplying blood to the skin to dilate along with the release of sweat on the skin surface to reduce temperature through evaporation. In addition to the involuntary regulation of temperature, the hypothalamus is able to communicate with the cerebral cortex to initiate voluntary control such as removing clothing or drinking cold water. With all regulations taken into account, the body is able to maintain core temperature within about two or three degrees Celsius during exercise. See alsoeditReferencesedit abc. Ross, Robert Blair, Steven N. Arena, Ross Church, Timothy S. Desprs, Jean Pierre Franklin, Barry A. Haskell, William L. Kaminsky, Leonard A. Levine, Benjamin D. Importance of Assessing Cardiorespiratory Fitness in Clinical Practice A Case for Fitness as a Clinical Vital Sign A Scientific Statement From the American Heart Association. Circulation. 1. 34 2. ISSN 0. 00. 9 7. PMID 2. CIR. 0. 00. 00. 00. Donatello, Rebeka J. Health, The Basics. San Francisco Pearson Education, Inc. Hillsdon, M. Foster, C. Thorogood, M. Interventions for promoting physical activity. The Cochrane Database of Systematic Reviews 1 CD0. ISSN 1. 46. 9 4. X. PMC 4. 16. 43. PMID 1. CD0. 03. 18. 0. pub. Pollock, M. L. Gaesser, G. A. 1. 99. 8. Acsm position stand the recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults. Medicine Science in Sports Exercise. PMID 9. 62. 46. 61. Brown, S. P. Eason, J. M. Miller, W. C. Exercise Physiology Basis of Human Movement in Health and Disease. Lippincott Williams Wilkins. ISBN 0. 78. 17. 77. Howley, E. T. and Powers, S. K. 1. 99. 0. Exercise Physiology Theory and Application to Fitness and Performance. Dubuque, IA Wm. C. Brown Publishers. ISBN 0. 07. 80. 22. Shaver, L. G. 1. Essentials of Exercise Physiology. MN Burgess Publishing Company. ISBN 0. 02. 40. 96. External linksedit.