Anatomical Alterations of the Cardiovascular and Respiratory Systems - Term Paper Example

The Potential Benefits to the Athletes of the Training Adaptations to the Cardiovascular and the Respiratory Systems Cardiovascular system and its components go through various adaptations after a period of training. The adaptations in the heart size, the decrease in the resting heart rate and in the blood pressure, at rest and during sub-maximal exercise, in both systolic and diastolic pressure, increase in stroke volume are some of the most important adaptations take place. The experts used to recommend the exercise minimum of 75 percent of one’s maximum heart rate for a healthy individual. Now the minimum is down to 60 percent to achieve cardiovascular benefits. (John Douillard, 1994). What are the specific significances of these benefits? At what time of the practice do we attain those benefits? And how do the cardiovascular and respiratory system really respond and cope with the long term training our athletes are accustomed to doing? The benefits of this adaptation in fact are not a new phenomenon. Diaphragm / intercostals, which are the respiratory muscles that control the respiratory flow, increase in strength. Thus, it maximizes the amount of oxygen can be taken up and utilized while breathing (http:/ /www.teachpe.com/anatomy/long_term_effects. php). Anatomical Alterations of the Cardiovascular and Respiratory Systems The different types of training methods have various ways of adaptation relevant to improve the athletic performance of the trainee. The following will appraise how these changes and adaptations are paving way to a higher level of performance in an athlete. The cardiovascular system consisting of a pair of pumps, the heart, and of various vessels — arteries, veins and capillaries — through which the blood, propelled by the heart, brings oxygen and other nutrients to cells in all parts of the body and carries away waste (Encyclopaedia Britannica, 1982). Exercise in human body normally serves for the following functions; such as a) Transports hormones b) Delivers nutrients and fuel to active tissues c) Transports heat (a by-product of activity) from the core to the skin d) Oxygenates blood by returning it to the lungs e) Delivers oxygen to working muscles. The respiratory system on the other hand is responsible for the gas exchange from the time oxygen enters the organism until carbon dioxide and water re given off. The organs used in breathing-nose, pharynx, larynx, trachea, bronchi, and lungs—are called the respiratory system. (Britannica Junior Encyclopaedia, 1980). The oxygen demand in the muscle is increased by exercise. At the same time more waste is created due to increased metabolic process. Body temperature rises with more nutrients. To perform as efficiently as possible the cardiovascular system must regulate these changes and meet the body’s increasing demands (http://www.sport-fitness-advisor.com). The muscle tissues at that time would be able to extract more oxygen from arterial blood. Consequently, the heart’s mass and volume increase and cardiac muscle undergoes the process called hypertrophy (the enlargement of a muscle belly due to an increase in the size of muscle cells - particularly the muscle's fibres). It is the left ventricle that adapts to the greatest extent. As well as the chamber size increasing as a result of endurance training (Cardiology Clinics, 1997 15:397-412), more recent studies show that the myocardial wall thickness also increases (J Sports Med, 17th Nov. 1996, Suppl 3:S140-4). A ten week exercise program will also cause a reduced resting heart rate. Highly conditioned athletes such as Lance Armstrong can even have resting heart rates in the low 30s. During this period of training and workout, an individual with an initial 80beats per minutes can reasonably expect to see a reduction of about 10beats/min in their resting heart rate (Wilmore JH and Costill DL., (2005). At low work rates there may only be a marginal difference in heart rate pre and post training. So, during sub-maximal exercise, heart rate is lower at any given intensity compared to pre-training. This difference is more marked at higher relative exercise intensities. As intensity reaches maximal levels, the difference can be as much as 30beats/min following training (Wilmore JH and Costill DL., (2005). Maximum heart beat would always appear to be genetically limited as it remains unchanged by workouts. Nevertheless maximum heart beat rates is much lesser in elite athletes than the untrained individuals of the same age. Following an exercise bout, Wilmore and Costill (2005) provide that the heart rate remains elevated before slowly recovering to a resting level. After a period of training, the time it takes for heart rate to recover to its resting value is shortened. Increase in stroke volume at rest can be noticed as another important adaptation the heart would be subjected to. After the training during sub-maximal exercise and maximal exercise, stroke volume at rest averages 50-70 ml/beat in untrained individuals, 70-90ml/beat in trained individuals and 90-110ml/beat in world-class endurance athletes (McArdle, Katch and Katch (2000). Willmore and Costill (2005) have attributed this all-round increase in stroke volume to greater end-diastolic filling. Reduced heart rate which increases the diastolic filling time and an increase in blood plasma and so blood volume are the two reasons by which this greater filling of the left ventricle takes place. More Blood Ejection According to the Frank-Starling mechanism, this increased filling on the left ventricle increases its elastic recoil thus producing a more forceful contraction. So not only is the heart filled with more blood to eject, it expels a greater percentage of the end-diastolic volume (referred to as the ejection fraction) compared to before training. Cardiac Output If heart rate reduces at rest and during sub-maximal exercise and stroke volume increases, what is the net effect on cardiac output? In genuine statement, cardiac output remains reasonably unaffected or decrease only slightly following endurance training. During maximal exercise on the other hand, cardiac output increases significantly. This is a effect of an increase in maximal stoke volume as maximal heart rate remains unchanged with training. In untrained individuals, maximal cardiac output may be 14-20L/min compared to 25-35L/min in trained subjects. In large, elite athletes, maximal cardiac output can be as high as 40L.min (Wilmore JH and Costill DL. (2005). Skeletal muscle also obtains a greater blood supply subsequent the training. This is due to improved number of passageways, greater opening of existing capillaries, more effective blood redistribution and increased blood volume. Blood pressure can decrease (both systolic and diastolic pressure) at rest and during sub-maximal exercise by as much as 10mmHg in people with hypertension. However, at a maximal exercise intensity systolic blood pressure is decreased compared to pre-training (Coyle EF, Hemmert MK, Coggan AR, Jan 1986;60(1):95-9, Clausen JP, 1977 57:779-816). Endurance training also increases blood volume. While plasma volume accounts for the majority of the increase, a greater production of red blood cells can also a contributory factor. Recall that hematocrit is the concentration of hemoglobin per unit of blood. An increase in red blood cells should increase hematocrit but this is not the case. Because blood plasma increases to a greater extent than red blood cells, hematocrit actually reduces following training. (The Cardiovascular System and Exercise, http://www.sport-fitness-advisor.com/cardiovascular-system-and-exercise.html) Relationship of adaptations with training methods and intensities Benefits of modest stamina exercise comprise of increases in parasympathetic activity and bar reflex sensitivity (BRS) and a relative decrease in sympathetic tone. A study on the entire Italian junior national team of rowing (n=7) at increasing training loads up to 75% and 100% of maximum, the latter 20 days before the Rowing World Championship. Increasing training load up to 75% of maximum was associated with a progressive resting bradycardia and increased indexes of cardiac vagal modulation and BRS. However, at 100% training load these effects were reversed, with increases in resting heart rate, diastolic BP, low-frequency RR interval, and BP variability and decreases in high-frequency RR variability and BRS. Three athletes later won medals in the World Championship. This study indicates that very intensive endurance training shifted the cardiovascular autonomic modulation from a parasympathetic toward a sympathetic predominance. This finding should be interpreted within the context of the substantial role played by the sympathetic nervous system in increasing cardiovascular performance at peak training. (American Heart Association, Inc, 13th May 2002) Altitude training prior to competition at sea level has been used by elite athletes since approximately 1968 (Peronnet, 1994). While it is well established that adequate acclimatization and physical training at altitude improves performance at altitude, it is questionable whether training at altitude also improves performance at sea level, more than training at sea level itself. The use of altitude training to optimally enhance sea level endurance performance is widely practiced by athletes and coaches who primarily believe that acclimatization to environmental hypoxia initiates a series of metabolic, muscular and cardio-respiratory adaptations that will influence oxygen transport and utilization. Additional beliefs for training at altitude include; improvement in coordination and reaction times, aerobic fitness during and post injury, a more rapid recovery between rounds of competition and between rounds at sea level, and for an aerobic boost prior to high intensity training. Therefore, this strategy is accumulating support from scientists, athletes, and coaches alike, as the most advantageous method for enhancing sea level performance in highly trained endurance athletes. (Nicola Brash, 2002) Living at altitude increases aerobic power at sea level primarily by increasing the ability of the circulatory system to transport oxygen to the muscles. The increase comes about through an increase in the number of red cells in the blood. The extra red cells are produced in response to an increase in release of erythropoietin (EPO) primarily during the first three weeks at altitude. Changes in buffering capacity of blood and muscles also occur, but these may be beneficial or harmful. Changes also occur in the respiratory system, but these are still under investigation. The physiological adaptations to training at altitude are apparently not beneficial, although there is no harm in doing low-intensity training at altitude. There is a large variation between athletes in the response to living at altitude. Some athletes have much larger increases in EPO than others at a given elevation. Athletes who have a low EPO response may need to live at a higher altitude. (http://sportsci.org/jour/0001/pf.html) Conclusion Even though the largest part of the increase in VO2max or the maximum volume of oxygen an athlete can use results from the increases in cardiac output and muscle blood flow, the increase in a-VO2 difference also plays a key role. This increase in a-VO2 difference is due to a more efficient circulation of arterial blood away from inactive tissue to the active tissue, so that more of the blood coming back to the right atrium has gone through active muscle. Once an athlete has achieved his genetically determined peak VO2max, he can still increase his endurance performance due to the body’s ability to perform at increasingly higher percentages of that VO2max for extended periods. The increase in performance without an increase in VO2max is a result of an increase in lactate threshold. (http://www.lcsc.edu/mcollins/Exercise%20Phys/08_cardiovascular_and_respiratory_adaptations.htm) As a recap, the cardiovascular adaptations to training increase the left ventricle size and wall thickness. It also increases resting, sub maximal and maximal stroke volume while the maximal heart rate decreases or stays the same. Output is better distributed to active muscles and maximal cardiac output increases. Blood volume increases, as does red cell volume, but to a lesser extent. Resting blood pressure does not change or decreases slightly, while blood pressure during sub maximal exercise decreases. As for the respiratory adaptations, the pulmonary ventilation increases during maximal effort after training; you can improve performance by training the inspiratory muscles. Pulmonary diffusion increases at maximal work rates. The a-VO2 or the maximal oxygen consumption difference increases with training due to more oxygen being extracted by tissues. The respiratory system is seldom a limiter of endurance performance. All the major adaptations of the respiratory system to training are most apparent during maximal exercise. The body and the systems composing it are designed for optimal performance in whatever endeavours thrown man’s way. And the great athlete knows just how to listen to his body. He can train all he wants. But as Ralph Waldo Emerson puts it—nothing great was ever achieved without enthusiasm. References American Heart Association, Inc., 13th May 2002, Conversion From Vagal to Sympathetic Predominance With Strenuous Training in High-Performance World Class Athletes , [online] available from: http://circ.ahajournals.org/cgi/content/abstract/105/23/2719?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=benefits+to+athletes&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT) [Accessed 3rd February 2010] Britannica Encyclopaedia, 1982, 15th Ed., pg. 561, U.S.A.: Encyclopaedia Britannica, Inc. Britannica Junior Encyclopaedia, 1980, pg. 73, U.S.A.: Encyclopaedia Britannica, Inc. Cardiology Clinics (1997) The athlete's heart and cardiovascular disease: impact of different sports and training on cardiac structure and function, 15:397-412 Clausen JP (1977) Effects of physical training on cardiovascular adjustments to exercise in man. Physiological Reviews. 57:779-816 Coyle EF, Hemmert MK, Coggan AR (1986) Effects of detraining on cardiovascular responses to exercise, Role of Blood Volume, J Appl Physiol, 60(1):95-9 Douillard, J (1994), Body, Mind and Sport, New York: Crown Trade Paperbacks Fagard RH (Nov 1996) Athlete's Heart: A Meta-analysis of the Echocardiographic Experience, Int J Sports Med, 17 Suppl 3:S140-4 McArdle WD, Katch FI and Katch VL. (2000) Essentials of Exercise Physiology: 2nd Edition, Philadelphia, PA: Lippincott Williams & Wilkins Nicola Brash (2002) Does Altitude Training Improve Sea Level Performance In Endurance Athletes? [online] Available from: http://physiotherapy.curtin.edu.au/resources/educational-resources/exphys/00/altitude.cfm [Accessed 2 February 2010] Peter Pfitzinger, MSc, Highlights of the Third Annual International Altitude-Training Symposium [online] available from: http://sportsci.org/jour/0001/pf.html [Accessed 3 February 2010] Sports Fitness Advisor, The Cardiovascular System and Exercise [online] Available from:http://www.sport-fitness-advisor.com/cardiovascular-system-and-exercise.html Wilmore JH and Costill DL. (2005), Physiology of Sport and Exercise: 3rd Edition, Champaign, IL: Human Kinetics Read More