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Exercise Physiology Packet with case study

Exercise Physiology Packet with case study - Exercise...

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Exercise Physiology Exercise is a disruption in homeostasis Feed forward responses: HR, ventilation rate 1. Metabolism and exercise Exercise demands a steady supply of ATP, which requires oxygen and other fuels ATP: Small amount from sarcoplasm Prosphocreatine breakdown donates P to ADP These only produce enough energy for ~10-15 sec of contraction Carbohydrates and fats are primary substrates Aerobic pathways are most efficient for ATP production Uses free fatty acids and glucose Anaerobic – when O2 requirements > O2 supply Pyruvate lactic acid ATP production 2.5X faster than aerobic, but only produces1ATP/glucose Glucose: Plasma glucose pool Intracellular stores of glycogen Glucose production from nonglucose precursors Hormones that affect glucose, fat metabolism are secreted during exercise Glucagon, catecholamines, cortisol Insulin secretion decreases despite increasing plasma glucose levels Sympathetic suppression of insulin secretion Reduces glucose uptake by non-muscle cells Oxygen consumption is related to exercise intensity Increase in O2 consumption increased after exercise 2. Respiratory Increased rate, depth of breathing increases alveolar ventilation Pathways: muscle mechanoreceptors, proprioceptors motor cortex respiratory control center (medulla) ventilation increases O2 use and ventilation rate need to be matched 3. Cardiovascular Increased sympathetic output ( CO, vasoconstriction) CO influenced by HR, force of contraction, venous return Venous return enhanced by skeletal muscle contraction Blood flow distributes: peripheral tissues – vasoconstriction Vasodilation in active muscle Blood pressure rises slightly during exercise MAP = CO X TPR Increased CO (net decrease in TPR as exercise continues) Baroreceptor adjust threshold – do not fire 4. Temperature – core temp controls temperature regulation 5. Renal - sweating, reduced urine production, increased water conservation, but increased osmolarity 6. Water intoxication – too much water consumption over short period of time – hypotonic ECF – cells swell
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Sixty minutes before the race, Jim was sitting quietly on the bank of the Schuylkill River. He was visualizing the race he was about to row. Two thousand meters of intense physical activity, pushing his body to the very limits of its capabilities. But sitting there, he was calm and relaxed, mentally willing his heart rate and respiratory rate down. He had done his stretching and warm-up exercises, but his heart rate was now just 65 beats per minute and he was breathing 12 breaths per minute. His body temperature was 37° C (98.6° F). He was well hydrated. His weight was 180 pounds. That was an hour ago. Now, he was sitting in the bow seat of the Men's Varsity Eight. In lane four on the starting line, he could see two boats to his left and three boats to his right. The rowers all looked bigger than him and his crew, but then they always did.
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