Journal of Exercise Medicine online

Transcription

1 1 Journal of Exercise Medicine online February 2017 Volume 2 Number 1 Official Research Journal of the American Society of Exercise Physiologists ISSN JEMonline Part I: The Role of the Board Certified Exercise Physiologist is to Explain the Physiologic Responses of Exercise Medicine Tommy Boone Board Certified Exercise Physiologists, Member of the Board of Directors, American Society of Exercise Physiologists, USA ABSTRACT Boone T. The Role of the Board Certified Exercise Physiologist is to Explain the Physiologic Responses of Exercise Medicine. JEMonline 2017;2(1):1-6. Exercise is such a powerful medicine that healthcare professionals are writing about regular exercise as the key to limiting and/or reversing chronic diseases. ASEP Board Certified Exercise Physiologists are prepared to evaluate clients and share their knowledge to minimize the risk of adverse events when exercising. Unfortunately, the reality is many adults is that they are not physically active or interested in the positive effects of exercise medicine. They think of exercise as boring or a waste of time. But, if adults were educated to the physiologic responses to exercise, then, they would be more willing to stay with the exercise medicine program. The purpose of this article is to present a brief breakdown of the physiologic responses to exercise that provides daily opportunities to make regular exercise a powerful mind and body medicine. It is the exercise physiologist who gives birth to the new reality and meaning of actualizing one s own potentialities in a healthy and positive experience of exercise. Key Words: Board Certified Exercise Physiologists, Exercise Medicine

2 2 INTRODUCTION Physical activity is medicine that helps to protect us from diseases of the cardiovascular system and other healthcare problems. It is such a wild card compared to standard medical treatment that it is truly difficult for society to acknowledge that exercise is medicine. Yet, overt diseases of many different origins are effectively treated by exercise. It is such a powerful medicine that healthcare professionals from around the world are writing about regular exercise as the key intervention to limiting and/or reversing the age-related decreases in symptomatic and otherwise asymptomatic individuals. Regular exercise is medicine, but for certain it is not a typical medical drug. Instead, physical activity is the exercise drug. This is the conclusion of countless numbers of research papers published around the world. When understood and properly prescribed, it is an excellent noninvasive healthcare practice that is the exercise physiologists answer to dozens of chronic diseases and disabilities. Fortunately, there are ASEP Board Certified Exercise Physiologists who are prepared with the physiological evaluation skills and scientific knowledge to minimize the risk of adverse events with regular exercise and training. They understand that adults who exercise regularly have the lowest risk of death (1), but first exercise medicine must be safely prescribed and, like any medicine, it must be valued and not overlooked. Aside from the expectation of exercise medicine to decrease the established risk factors that associate with coronary disease and the development of atherosclerosis, exercise medicine results in numerous positive effects on endothelial function of vascular cells. In fact, there is evidence that exercise medicine is linked to positive health related changes in the endothelium of the coronary arteries (2,3). In particular, exercise medicine is linked to endotheliumdependent dilation and increased coronary blood flow. The role of physical activity is very convincing in slowing and reversing the progression of atherosclerotic coronary artery disease (4,5). Moreover, exercise medicine increases HDL cholesterol while lowering LDL cholesterol, enhances glucose tolerance, improves insulin sensitivity, decreases stress and body weight, reduces blood pressure, and improves cardiovascular function (5). Of course to begin an exercise program requires a change in a person s lifestyle. This is in itself a difficult task, if not seemingly impossible for some individuals. Yet, regardless of age and gender, the exercise physiologists clients and/or patients must be willing to modify their lifestyle if they are to benefit from regular physical activity. They need to understand that as little as 30 min of brisk walking on most, if not all, days of the week can improve their health and quality of life. Statistically speaking, an increase in physical activity means better health and, therefore, less need for traditional medications that may or may not help reduce the risk of premature mortality from obesity, hypertension, diabetes mellitus, colon cancer, and cardiovascular diseases (6). But, unfortunately, our present day reality is such that the majority of American adults are not physically active or even interested in the effects of exercise medicine on the cardiovascular and musculoskeletal systems or the research that suggests physical activity relieves the symptoms of depression and anxiety. Interestingly, women are generally less likely to embrace exercise medicine than men. This is true whether it is aerobic exercise training such as light-to-moderate walking and cycling or strengthening activities. Part of the reason may be their lack of confidence in knowing what to do, when to do it, and for how long. But, in this regards, it is important to remember that exercise

3 by brisk walking, cycling, swimming, or yard work just 30 min d -1 3 times wk -1 is sufficient to lower cardiovascular morbidity and mortality. Then, the icing on the cake is to develop muscular strength and joint flexibility by engaging in resistance and flexibility training, respectively, at least 2 d wk -1. The risk of an injury is very low, especially with supervision by an exercise physiologist. The exception is the individual between 50 and 60 yrs old with several risk factors for cardiovascular disease. A potential client would do well to speak with his or her physician, although the risk of complications or death is very low when engaged in exercise during the supervision of an exercise physiology healthcare professional. Exercise is challenging. There isn t any question about it. Most anyone will agree, regardless of age. That is why the participation in regular exercise isn t what it should be. But, with the right information, people of all ages and gender with and without chronic diseases and disabilities can learn the joy of engaging in regular exercise medicine several times a week or even more frequently. What the ASEP Board Certified Exercise Physiologist can do is explain the changes in ways that clients and patients can understand. The more they gain an understanding of the physiologic responses to exercise, the more likely that the exercise will become part of their lifestyle. Aside from the increase in efficiency of the musculoskeletal system, there are many not so obvious responses when staying with an exercise medicine training program. The following is a brief breakdown of the physiologic responses to exercise that provides daily opportunities to make regular exercise a powerful mind and body medicine. Part II will be published in the April issue of 2017 JEMonline. It will present the physiologic adaptations to regular exercise that set the stage for a sustained increase in health and well-being. PHYSIOLOGIC RESPONSES TO EXERCISE MEDICINE The most obvious physiologic responses are specific to the respiratory and cardiovascular systems. It should be obvious that breathing is vital to surviving. The responses specific to the respiratory system include breathing in oxygen from the atmosphere and exhaling carbon dioxide. The oxygen leaves the lungs via the alveoli to enter the blood to be carried by hemoglobin in the blood to the cells of the body and, in particular, to the muscles because oxygen is necessary at the cellular level to produce energy in the form of adenosine triphosphate, ATP. The energy is used to fuel muscle contraction, which produces movement such as walking or jogging. To help ensure that the muscles get the oxygen they need, the lungs go to work immediately upon starting to exercise. There is an increase in the respiratory rate and tidal volume. As the client engages in a walking exercise from level ground to up a hill, the stress of non-stop muscle contraction against a heavier amount of work is likely to take place without the muscles getting enough oxygen. The exercise increases the carbon dioxide production and hydrogen ions that result in an increase in expired ventilation (7). The muscles response to the need to continue moving the body is to extract more oxygen, that is, if they can. There is a mixture of factors that must come together to ensure that adequate oxygen is at the cell level to produce energy for muscle contraction. But, it is important to acknowledge that not all muscles are alike. Some are slow-twitch fibers while others are fasttwitch fibers. Not every person has the same percentage of each. Some have more of one or the other. If there is oxygen available at the muscle cells, the high oxidative capacity of the slowtwitch fibers helps to ensure a high oxidative response that resists becoming fatigued due to their high blood flow capacity, high capillary density, and high mitochondrial content (8). The fast twitch fibers, on the other hand, are divided into fast-twitch a and b. The fast-twitch b fibers 3

4 also have a high oxidative capacity, but only moderately so compared to the slow-twitch fibers. When the exercise gets a bit more intense, the fast-twitch fibers are engaged with an increase in contractile speed. But, if there is the need to run very fast for 10 to 20 sec, the fast-twitch a fibers that have a high glycolytic capacity will engage to provide energy from the stored ATP in the cells. Exercise medicine should be a slow low-to-moderate intensity that does not produce a reliance on the glycolytic energy system to produce ATP. A high rate of work is not necessary to benefit from the prescriptive medicine of regular exercise. Therefore, it is imperative that clients and patients understand that the purpose of the low-to-moderate exercise intensity is to produce ATP in the presence of adequate oxygen at the cellular level. This means that the mitochondria within the muscles generate the ATP primarily from carbohydrate and fat. At the same time, the client s oxygen consumption (VO 2 ) is consistent with the intensity of the exercise. As the client, for example, walks equally as comfortable at a 14-min mile pace for 2 mi as he/she did earlier on at 24 min for 1 mi, then, it is more than reasonable to conclude that his/her cardiorespiratory fitness (i.e., aerobic power) is increased as a result of the exercise medicine program (9). Here, it is important to point out that without the cardiovascular responses to exercise the work of the respiratory system would not be enough. But, working together they give us life and all that goes with it, including exercise to increase the quality of the mind and body. To begin with, the cardiovascular system consists of the myocardium (i.e., the heart) and the vascular system (or blood vessels). The role of each is dependent upon the activity of the muscles and the need for oxygen. Thus, the transition from rest to exercise requires more ATP for muscle contraction that is made possible by the central and peripheral nervous systems. For example, if the client has been encouraged to transition into a brisk walk versus a very slow walk, he/she will have to think about moving the lower limbs faster. Faster body movements take place by consciously making the decision to walk faster, which requires the frontal lobe of the brain to increase its influence (i.e., impulses) on the motor cortex of the brain to send more impulses down the spinal cord to initiate a faster firing of the peripheral nervous system. This system represents the nerves to the muscles, and in this case to the muscles of thighs and legs. With increased nerve impulses via the femoral nerves to the quadriceps to flex the hip and extend the knee joint (to help initiate the next step and to secure the weight of the body during slight knee flexion) and the obturator nerves to the adductors to aid in flexion of the hip and keep the thighs under the body, the thighs begin to move faster. This adjustment is accompanied by increased neural activity through the tibia nerves to the plantar flexors (located on the posterior aspect of the legs) to sustain the weight of the body with the placement of the feet. With the increase in walking speed the muscles become more active, thus requiring more energy to sustain the increase in contraction. The increased need for oxygen is met in two ways. First, there is the increase in cardiac output, which is the volume of blood pumped by the left ventricle per minute to the peripheral tissues. The increased cardiac output is made possible by the increase in activity of the sympathetic nervous system that increases heart rate, given that cardiac output is the product of heart rate and stroke volume. Second, the increase in ventricular contractility pumps more blood out of the ventricles through the vascular system to the active muscles (via the left ventricle) and to the lungs (via the right ventricle). The left ventricular volume of oxygenated blood from the lungs is called stroke volume, which increases with the 4

5 increase in ventricular contractility. The right ventricular stroke volume is low in oxygen and high in carbon dioxide from the active muscles. When the blood reaches the lungs, the carbon dioxide leaves the blood to go into the lungs to be exhaled. At this point it is important to mention that the availability of oxygen at the muscle tissue level is made possible by the role that hemoglobin plays in the transport of oxygen from the lungs to the heart and from the heart throughout the vascular system to the muscles. The greater the increase in cardiac output along with the normal concentration of hemoglobin in the blood the greater the transport of oxygen. As the increase in blood flow reaches the muscles, oxygen leaves the hemoglobin to accommodate specific functions related to the muscles mitochondria that allows for the development of ATP. CONCLUSIONS Physical activity can be designed as physical exercise, which can be prescribed as exercise medicine (9) by an ASEP Board Certified Exercise Physiologist to decrease risk factors linked to chronic diseases and disabilities. Why then aren t more adults exercising and seeking out the guidance of an exercise physiologist? The short answer is that it requires a state of mind that is different from the present day way of thinking. Most people simply do not have the discipline to exercise even though they may understand it is necessary. It is easier to play on the computer or watch a football game on TV and consume calories from redundant eating. When it does click that their blood pressure is elevated or that they have gained another 10 lbs a second year in a role, perhaps then, they will begin to think about exercising. Of the adults who actually start walking, only a few will stay with it. This is where the Board Certified Exercise Physiologist can help motivate individuals to stay with the exercise program, particularly from the point of view that exercise is medicine. But, like most medicines, it should be taken with caution. Exercise physiologists are educated to help their clients and patients understand the physiologic responses to exercise. This point is important, given that it provides meaning to the repetitious physical acts of walking around the block or lifting weights. The exercise physiologist can help keep the exercise response centered within one s own being, without which there is often the lack of desire to continue exercising. Because of this thinking, clients and patients need to be educated to the physiologic responses that are specific to exercise medicine. 5 Address for correspondence: Tommy Boone, PhD, MPH, MAM, MBA, 104 Taylors Cove, Beaumont, TX 77705, tbooneasep@gmail.com REFERENCES 1. Bouchard C, Blair SN, Haskell W. Physical Activity and Health. (2nd Edition). Champaign, IL: Human Kinetics, Bowles DK. Adaptation of ion channels in the microcirculation to exercise training. Microcirculation. 2000;7:25-40.

6 3. Hambrecht RA, Wolf S. Gielen, et al. Effect of exercise on coronary endothelial function in patients with coronary artery disease. N Engl J Med. 2000;342: Franklin BA, Khan JK. Delayed progression or regression of coronary atherosclerosis with intensive risk factor modification: Effects of diet, drugs, and exercise. Sports Med. 1996;22: Smit JK. Exercise and athegenesis. Exerc Sport Sci Rev. 2001;29 (2): American College of Sports Medicine. Position stand: Exercise and hypertension. Med Sci Sports Exerc. 2004; Boone T. Introduction to Exercise Physiology. Burlington, MA: Jones and Bartlett Publishing, Terjung RL. Muscle adaptations to aerobic training. Sports Sci Exchange. 1995;8: Boone T. ASEP s Exercise Medicine Text for Exercise Physiologists. Beijing, China: Bentham Science Publishing, Disclaimer The opinions expressed in JEPonline are those of the authors and are not attributable to JEPonline, the editorial staff or the ASEP organization.