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EXERCISE PHYSIOLOGY

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  1. EXERCISE PHYSIOLOGY Prof K. Sivapalan Department of Physiology, Faculty of Medicine, University of Jaffna

  2. What is exercise? • Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. • It is performed for various reasons including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, as well as for the purpose of enjoyment. • Day to day activities involving musculo-skeletal system also gives the same effect as exercise but it depends on the intensity and extent of the work involved. Exercise Physiology

  3. Muscle strength • The strength of a muscle is determined mainly by its size • Maximal contractile force is between 3 and 4 kg/cm2 of muscle cross-sectional area [number of myofibrils]. • Cross sectional area of the quadriceps of world class weight lifter- 150 cm2 – 525 kg. • The holding strength of muscles is about 40 per cent greater than the contractile strength. • This would increase the strength to 735 kg. Exercise Physiology

  4. Power • Power is determined by strength, distance of contraction and number of times per minute. • Power is the work done in a unit time- expressed as kg-m/min. Exercise Physiology

  5. Maximal Power • The maximal power [kg-m/min] achievable by all the muscles in a highly trained athlete: • First 8 to 10 seconds 7000 • Next 1 minute 4000 • Next 30 minutes 1700 • The power output of the muscles is only one fourth as great as during the initial power surge. • Efficiency of translation of power to performance is low at rapid activity than sustained activity: velocity of 100 M dash is only 1.75 times more than 30 minute race. Exercise Physiology

  6. Endurance • Ability to remain active for a long period. • Related to the nutritive support for the muscle Exercise Physiology

  7. Muscle Metabolic Systems • The amount of ATP present in the muscles, even in a well-trained athlete, is sufficient to sustain maximal muscle power for only about 3 seconds • The combined amounts of cell ATP and cell phosphocreatine can provide maximal muscle power for 8 to 10 seconds • Glycogen-lactic acid system can provide 1.3 to 1.6 minutes of maximal muscle activity. • This system can form ATP molecules about 2.5 times as rapidly as can the oxidative mechanism of the mitochondria. Exercise Physiology

  8. Glycogen Usage and Recovery in Relation to Dietary regime Exercise Physiology

  9. Energy Substrate and Dietary Regime Exercise Physiology

  10. Developing Strength by Training • Muscles that contract at more than 50 % of the maximal force develop strength rapidly even if done few contractions per day. • Contractions with less force, without resistance, will not develop strength irrespective of the extent. Exercise Physiology

  11. Effects of Training Exercise Physiology

  12. Effects of Training on Muscles • Hypertrophy – increased myofibrils. • Increase in mitochondrial enzymes [120%] • Phosphagen metabolic system [60-80%] • Stored glycogen [50%] • Stored triglyceride [75-100%] • Rate and efficiency of oxidative metabolic system [45%] Exercise Physiology

  13. Muscle types Exercise Physiology

  14. Hereditary Differences • Proportion of fast or slow twitch fibers appears to be genetically determined. • Change of the muscle type on training is minimal. • Percentages of fibers in quadriceps muscle: Exercise Physiology

  15. Respiration in Exercise • Oxygen consumption [ml/min] under maximal conditions: • Untrained average male 3600 • Athletically trained male 4000 • Male marathon runner 5100 • Relation between oxygen consumption and pulmonary ventilation is linear. • Limits of pulmonary ventilation L/min: • Maximal exercise ventilation- 100-110 • Maximal breathing capacity 150-170 Exercise Physiology

  16. V O2 Max • Training increases oxygen maximal consumption in about 8 weeks by 10% • Oxygen diffusing capacity appears to be genetically determined: • Nonathlete at rest [ml/min] 23 • Nonathlete on maximal exercise 48 • Speed skaters on maximal exercise 64 • Swimmers on maximal exercise 71 • Oarsman on maximal exercise 80 Exercise Physiology

  17. Diffusing Capacity • The increase during exercise is due to increased pulmonary blood flow. • Blood flow through many capillaries at rest is sluggish but increased blood flow provides larger surface for diffusion. • Genetic predisposition for diffusing capacity? • Not much change in arterial blood gas concentration in exercise. • Stimuli for Increased Respiration: • Motor out flow on respiratory center. • Proprioception from muscles and joints Exercise Physiology

  18. Effects of Smoking • Nicotine causes constriction of the terminal bronchioles of the lungs, which increases the resistance of airflow. • Irritating effects of the smoke increases fluid secretion into the bronchial tree and swelling of the epithelial linings. • Nicotine paralyzes the cilia of the respiratory epithelial cells and debris accumulates in the passageways and adds to the difficulty of breathing. • Chronic smoking- • Emphysema • Chronic bronchitis • Obstruction of terminal bronchiols • Destruction of alveolar walls Exercise Physiology

  19. Muscle Blood Flow Exercise Physiology

  20. Cardiovascular System in Exercise • Resting blood flow to resting muscle- 3.6 ml/100 g muscle/min • During maximal exercise- 90 ml/100g/min • Cardiac Output: • Young man at rest- 5.5 • Young man at maximal exercise 23 • Marathoner at maximal exercise 30 Exercise Physiology

  21. Changes in Heart • In marathoners, • Volume of chambers increase by 40 % • Heart mass increase by 40 % Exercise Physiology

  22. Body Heat in Exercise • Heat production increases with exercise which can in crease body temperature to dangerous level due to inability to eliminate the heat in hot and humid environment or heavy clothing. • Heat stroke: when body temperature goes to 41-42 °C, it is destructive to tissue cells [including brain] – symptoms are, • Extreme weakness, exhaustion, headache, dizziness, nausea, profuse sweating, confusion, staggering gait, collapse, and unconsciousness • It is fatal because temperature regulation is lost and many enzymes have doubled their activities. Exercise Physiology

  23. Body Fluids and Salt • Fluid loss: • Sweating • Tissue fluids in muscles • Effect on reduction of body weight by: • 3%: diminished performance • 5-10%: muscle cramps, nausea etc. • By hypovoluaemia, haemoconcentration, hyponatreamia, hypokalaemia [aldosterone] Exercise Physiology

  24. Warming Up • Increases performance by staircase phenomenon Exercise Physiology

  25. Starting Position • Starling law of relationship to initial length to the force generated. Exercise Physiology

  26. Sports Nutrition • High carbohydrate diet vs high fat diet • ? Protein intake • Vitamins and minerals Exercise Physiology

  27. Sports Dress • Facilitate heat loss Exercise Physiology

  28. SEX DIFFERENCE • Quality- same • Quantity- more in males due to testesteron • Endurance- females have advantage because of high energy store • Problems of menstruation, pregnancy • ? Efficiency due to pelvic and other skeletal structural differences. Exercise Physiology

  29. BENEFITS AND PROBLEMS OF EXERCISE Prof K. Sivapalan Department of Physiology, Faculty of Medicine, University of Jaffna

  30. Introduction • Evolution: hunter-gatherer • Body Composition: Muscles (40%)and Bones • Motor Centers in Brain: Cerebellum and Basal ganglia, Motor Cortex, Brain Stem and Spinal Cord • Control of physical activity: Neocortex [on the basis of short and long term health, physical and other benefits] vs Limbic System [on the basis of emotion] • Technology: Automation and communication → comfort → unhealthy life style • Tissues: “USE IT OR LOSE IT” Exercise Physiology

  31. Nutrition • Energy intake = exercise energy expenditure + energy needed for all other functions ± body energy content • Inadequate energy intake: ↓ muscle mass; ↓bone density; ↑risk of fatigue, injury, and illness and reproductive dysfunction. • Eating: before or after exercise- before for glycaemic control. • Vitamins and minerals: Vitamins B, C, D, E and beta carotene and minerals like calcium, iron, zinc, magnesium and selenium – ?weight reduction and diet restriction. • Fluid & electrolytes: dehydration and hyponatremia (muscle cramps) Exercise Physiology

  32. Metabolism • Enzymes for oxidation of Fat- ↑, Carbohydrate- ↓ • ↑ oxidative capacity, ↓ glycogen depletion • ↑ insulin sensitivity and ↓ leptin level • When Energy Intake >Energy Expenditure, ↑ serum cholesterol and phospholipids. • Sprint- ↑post-exercise metabolism –weight reduction. Exercise Physiology

  33. Exercise and Diabetes • Regular exercise reduces the risk of type 2 diabetes in overweight/obese individuals. • Regular walking exercise: increased energy consumption, and decreased FBG, HbA1c, and TG levels. Better response if done after dinner. • Incidence of complications of type II diabetes might be reduced by implementing a regular walking exercise program. • Moderate exercise: muscular uptake of glucose exceeds hepatic glucose production, and blood glucose decline during the activity. • Plasma insulin levels concomitantly fall, making the risk of exercise-induced hypoglycemia low as long as the individual is not injecting insulin or taking insulin secretagogues. Exercise Physiology

  34. Skeletal Muscles • Hypertrophy • Feed arteries in rats: young- increase in number of vessels, old- increased cross sectional area of the vessels • Gene expression: heat shock proteins- maintain homeostasis, facilitate repair from injury and preserve muscle function in aging. • Anabolic effect of nutrient intake- prevent sarcopenia in old age. Exercise Physiology

  35. Bones, Tendons and Ligaments • Articular cartilage volume: proportional to physical activity – exercise in older women did not show increase. • Postmortom findings in Horse: increase in hyaline cartilage, calcified cartilage and subchondral bone thickness- ? Growing children. • Joint form: during postnatal ontogeny, it is modified primarily through differential rates of articular cartilage proliferation across articular surfaces. ? Regulated by the magnitude and orientation of stresses in the articular cartilage. • Epiphysial growth is stimulated by weight bearing. • Bone mass and architecture: Load-bearing is an important functional influence. Bone's adaptive response to load-bearing depends on functional strains. Remodeling – along the line of stress. • Fibroblast growth factor 21: research on blood glucose. ? Action on tissues- contribution in making tendons and ligaments stronger. Exercise Physiology

  36. Injuries • Excessive weight bearing on epiphysis - damage and stunting. • Injuries to muscles and bones occur by over use, accidents and foul play in games. • More physically active individuals had more knee abnormalities. • ? Running and osteoarthritis- may depend on pre-existing health of the joint. • Stress of competitive sports overweigh the benefits of exercise by the action of stress hormones. • Effects of exercise in illnesses like viral infections, liver diseases and kidney diseases need consideration. Exercise Physiology

  37. Immunity • Antibody production: optimal in moderate exercise, suppression in intense exercise. • This transient suppression returns to normal in 24 hours. ? Can become a chronic depression of acquired immunityif intense exercise continues- may be due to elevated circulating stress hormones, alterations in the pro/anti-inflammatory cytokine balance • Exercise alters the number and function of neutrophils, monocytes and natural killer cells- ?anti inflammatory effect of exercise. • Prophylactic effect on insulin resistance, atherosclerosis, tumour growth and neurodegeneration. ? Antiinflammatory effect • Enhanced anti-tumour immunity: ?protection against postmenopausal breast cancer and cancers of colon, endometrium, lung and pancreas. • AIDS: Moderate physical activity may slow HIV disease progression. Exercise Physiology

  38. Respiratory System • Improved pulmonary function at rest and exercise [greator operating lung volumes] • ?increased incidence of respiratory infection- ?immuno-suppression by exercise. ? Cool air and dust load of hyperventilation.? Body temperature fluctuations- exercise and bathing. • Exercise induced asthma- ?triggered by cool air • Significant benefits from exercise training in Acute Exacerbation of Chronic Obstructive Pulmonary Disease, COPD, and conditions that are common co-morbidities Exercise Physiology

  39. Blood • Thrombotic risk increases with aging-↑fibrinogen, factor VII, PAI-1 and plasma viscosity. Regular physical exercise ↓ risk • Acute exercise [unaccustomed strenuous physical exertion]: transient activation of the coagulation system, accompanied by an increase in the fibrinolytic capacity. • Acute exertion may precipitate ischeamic cardiac problems due to: • Increased coagulability • ?reduced plasma volume and haemo-concentration • Rupture of a small, inflamed, coronary plaque and the activation of thrombogenic factors • Long-term moderate or strenuous physical activity is associated with a considerable reduction in cardiovascular morbidity and mortality. Exercise Physiology

  40. Cardiovascular System • Resting heart rate, heart rate recovery, exercise HR, and exercise blood pressure: strong association in runners and swimmers, less in walkers and least in sedentary. • Larger end diastolic volume and wall thickness, more in males [not exceeded the limit of resolution]. • Transport capacity: ↑blood flow and capillary exchange. Structural- cross-sectional area and angiogenesis- vascular remodelling. Functional- control of vascular resistance. • Improve endothelial function, vascular smooth muscle function, antioxident systems, heat shock proteins, ↓inflammation. • While strenuous exercise increases oxidative metabolism and produces a pro-oxidant environment, regular moderate physical activity promotes an antioxidant state and preserves endothelial function. Exercise Physiology

  41. Cardiovascular Rehabilitation • Lowering BP: A bout of afternoon exercise interrupted with short rest periods is recommended • After Coronary Bypass: improved exercise capacity associated with restorations of peripheral oxygen utilization in both patients with and without Diabetes. • Congestive Heart Failure: Aquatic exercise improves exercise capacity and muscle function in patients with the combination of CHF and DM • Intermittent Claudication: no improvement observed in experiment on old women. • Exercise training: effective antioxidant and anti-atherogenic therapy • Adverse events observed:12.2% for SBP, 10.4% for TG, and 13.3% for HDL-C. About 7% of participants experienced adverse responses in two or more risk factors. Exercise Physiology

  42. Higher Functions of the Brain • Early life stress- maternal separation- ?reversed by exercise in rats. • Reduction of depression and fear of falling in older persons by physical training • Exercise training resulted in significant improvements in depressive symptoms, fatigue and aspects of quality of life • Exercise with integrated cognitive and motor coordination, may help with preservation of global ability in elders at risk of cognitive decline – observed in Chinese old subjects • Other suggested benefits- improved problem solving ability and feeling of wellbeing Exercise Physiology

  43. Sleep • Exercise has been recommended for enhancing sleep- 5-6 hours before sleep time. In animals- exercise increases NREM sleep. • Six months of training improved sleep in elderly. • Participation in an exercise training program had moderately positive effects on sleep quality in middle-aged and older adults. • Moderate treatment efficacy for the reduction of apnea-hypopnea index [AHI] in sedentary overweight/obese adults: exercise may be beneficial for the management of obstructive sleep apnoea • Exercise seems to improve the mobility, fatigue, and sleep quality in Stage IV lung and colorectal cancer patients. • Physical exercise could be an alternative or complementary approach to existing therapies for sleep problems. Exercise Physiology

  44. Reproductive System • Physical Working Capacity (at HR170) is decreased in luteal and menstrual phases • Strenuous exercise: delayed puberty, luteal phase deficiency, oligo-amenorrhea or anovulation – disturbance of GnRHpulsatility due to ? inadequate energy intake. ?Role of leptin. • Hypoestrogenemia: premature osteoporosis. Most cases are reversible with dietary and exercise modifications. • Safe limits of aerobic exercise in pregnancy depend on previous exercise habits. • Pre-eclampsia: improved blood flow, reduced blood pressure, enhanced placental growth and vascularity, increased activity of antioxidant enzymes, reduced oxidative stress and restored vascular endothelial dysfunction. • Menopausal symptoms- [night sweats, mood swings, and irritability] reduced by aerobic training. • High impact sports activities may produce urinary incontinence Exercise Physiology

  45. Sexuality • Sexuality enhancement in male subjects (frequency of various intimate activities, reliability of adequate functioning during sex, percentage of satisfying orgasms, etc) was proportional to fitness achieved. • Reduced / abstenance of sexual activity following cardiac events: fear of coital death or re-infarction, dyspnea, anxiety, angina pectoris, exhaustion, depression, loss of libido, impotence, partners anxiety or concern, and feeling of guilt. • Patient that can climb one or two flights of stairs can keep his marital sexual life without running further risk or even experiencing cardiac symptoms • ?Risk of Myocardial Infarction during sexual activity is three times higher [Sex act as acute exercise] • Regular exercising- significant protective effect, improved sexual activity • Erectile dysfunction in middle-aged men is often improved by physical activity. • Adolescents indulge in sexual activities due to lack of recreation- exercise Exercise Physiology

  46. Rehabilitation - Cancer • Prostate cancer: positive benefits for improving surgical outcomes, reducing symptom experience, managing side effects of radiation and chemotherapy, improving psychological health, maintaining physical function, and reducing fat gain and muscle and bone loss. • Increase survivorship by 50%-60% in breast and colorectal cancers. • In the wide range of cancer populations, both young and old, and with curative and palliative intent, exercise is well tolerated and benefits the patient psychologically and physically. Exercise Physiology

  47. Rehabilitation- old age • The proportion of the aged population is increasing and minor illness will render them dependent • Exercise training was feasible and effective in reducing fear of falling and improving dynamic balance and isometric strength in institutionalized older people with fear of falling. • Older women can effectively change the decline in physical ability associated with aging by exercising. • The 60-65 year group was capable of converting physical activity into health benefits in both the short and long term. Exercise Physiology

  48. Conclusion • There is much evidence that a moderate amount of exercise is needed for the maintenance of functional integrity of all body systems. • It is important for growth and development of children • Not only can exercise reverse the effects of immobilization, it can readily produce a further 10 to 20% improvement in strength and aerobic power, effectively postponing functionally important thresholds for some 10 to 20 years. • In the west, regular exercise is rapidly gaining widespread advocacy as a preventative measure in schools, medical circles and in the popular media • In a Medical Faculty in India, of those who were currently exercising(50%), the proportion of boys was (62%) more compared to girls (38%). Lack of time, laziness, and exhaustion from academic activities were identified as important factors for not doing exercise. Exercise Physiology

  49. WHO Recommendations (more exercise- more health benefits) • 5–17 years: • at least 60 minutes of moderate to vigorous-intensity physical activity daily. • 18–64 years: [in bouts of minimum of10 minutes] • at least150 minutes of moderate-intensity aerobic physical activity weekly, or • At least 75 minutes of vigorous-intensity aerobic physical activity weekly, or • an equivalent combination. • > 64 years: • as above depending on their abilities and conditions. Exercise Physiology

  50. For Healthy life… Life long moderate exercise is a need but stressful exercise can be harmful Exercise Physiology