Aerobic exercise is a brisk physical activity that requires both the heart and lungs to work harder to meet the body's increased oxygen demand during physical exercise. Aerobic exercise can include running, cycling, and swimming or any other physical activity that enhances physical wellness and overall health. There are several benefits to aerobic exercise: increased cardiac function, weight loss, improved mental health and immune system, reduced disease rate and increased longevity. How much physical exercise should be performed to experience such benefits? The American College of Sports Medicine (ACSM) and the American Heart Association (AHA) physical activity guidelines recommend moderately intense 30 minute cardio workout a day for five days a week. For a more intense cardio workout, 20 minutes sessions should be performed a day for three days a week. For strength-training workout, 8 to 10 exercises should be performed with 8-12 reps twice a week for each exercise.[1] Aerobic exercise depends on many factors such as the number of years a person has been exercising, age, gender, training experience, and neutral biomechanics. Hence, to answer the question how much aerobic exercise is too much is fairly complex. For example, a beginner exerciser who might be eager to achieve results very quickly may suffer injury. On the other hand, some marathoners and ironmen easily complete 100 mile runs and 200 mile rides each week injury free. A main factor which should be considered is during aerobic exercise the equilibrium of the internal environment of the human body is challenged by the body’s generating force, power and heat. This causes the body to lose essential resources. Depletion of essential resources may easily lead to "the catastrophic failure model", chronic fatigue syndrome, and overtraining. · The catastrophic failure model means exercise has to stop, because one or more of the bodily systems are stressed beyond capacity. For example, when the muscles only get a limited amount of oxygen and nutrition supply, local intramuscular hypoxia and, anaerobiosis and thus exhaustion will occur.[2] · Chronic fatigue syndrome, or CFS, is a debilitating and complex disorder characterized by profound fatigue. This fatigue is not improved by bed rest and could be worsened by physical or mental activity. People with CFS most often function at a substantially lower level of activity than they are normally capable of. Researchers of Nijmegen Expert Centre of Chronic Fatigue discovered a reduced thickness of the cerebral cortex in female patients with CFS. Hence, there is a correlation between physical activity level, capacity, and reduction in the brain’s grey matter. · Overtraining is a late stage of intense and prolonged exercise during which the exercise performance declines instead of becoming better. The symptoms of overtraining are similar to those of the catastrophic failure model; the intensity of training is reduced or the training is completely stopped. Another factor which should be considered is the onset of blood lactate accumulation. This is due to the lactate accumulation at a slightly higher exercise intensity then lactate threshold. Homeostasis of the internal environment is affected by the accumulation of lactate, ammonia, acid, and body heat. All of these toxins may cause symptoms such as headaches, fatigue, memory loss, "flulike symptoms, and musculoskeletal pains.[3] The heightened acidity level of the body can inhibit the synthesis of DNA-RNA and cellular regeneration which can result in mutated cells or cancer. In the David Nieman interview of endurance, Mr Nieman talked about how cancer might be linked to elite endurance trainers. Examples that support this statement are the sub-four-minute miler Steve Scott and Armstrong who were both diagnosed with testicular cancer. Furthermore, the legendary runner, Marty Liquori suffered from lymphatic cancer. Besides causing sicknesses, too much exercise can also lead to injury. Prolonged exercise can constantly stress the same muscles, ligaments, and tendons by using the same repetitive contractions. For example, exercise-induced muscle damage (EIMD) is an unaccustomed physical activity of great intensity or duration.[4] Symptoms may include stiffness, swelling, decreased force of muscular contraction, and delayed-onset muscle soreness. Many times, regardless of the human body’s exhaustion and injuries, an individual would not miss a planned run or an exercise session. When a person can’t live without exercise, or when there are signs of severe withdrawal symptoms when a training session is missed, a person is said to be exercise addicted.[5] Exercise produces endorphins which create a good feeling leading to a positive mood change. Individuals that are exercise-addicts might not even have a positive experience while exercising. Despite this, they exercise anyway in order to avoid the negative feelings that stem from lack of exercise. Since the exercise addicts’ body is used to a lot of training and exercise, it takes more and more exercise to reach the same level of endorphin rush as before, which in return drives the body to exhaustion. Aerobic exercise is a physical activity which helps improve physical and mental health. Exercises like running, cycling, and swimming should be implemented in everyone’s fitness and exercise routine. These exercises could help everyone achieve their health and fitness goals. However, failure to pay attention to the body's signals before, during, and after exercise may result in fatigue, exhaustion, overtraining, injury, and/or exercise addiction. Every human body is different and each individual has a different training experience and neutral biomechanics. Therefore, it is advised for everyone to consult a health and fitness professional before starting exercise, or changing exercise regimens, or experiencing any sorts of pain. 1. American College of Sports Medicine: Physical activity guidelines, 2007 2. Ament W. and Verkerke G.: Exercise and fatigue. Sports Medicine: 2009; 39 (5) 389-442 3. Krohn J. and Taylor F. Natural detoxification. A practical encyclopedia: a complete guide to clearing your body of toxins: 5p 4. Stevenson R. Is supplementary aerobic training necessary for the marathon. Marathon and beyond. March/April 2011; 32-42 5. Fisher L. Wrisberg C. Sport physiology and counseling: Recognizing and dealing with exercise addiction. Athletic therapy today. 2004 Human Kinetics-ATT 9 (1). pp 36-37 |
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