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

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Presentation on theme: "Prof K. Sivapalan Department of Physiology, Faculty of Medicine, University of Jaffna."— Presentation transcript:

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

2 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 Physiology2

3 The strength of a muscle is determined mainly by its size Maximal contractile force is between 3 and 4 kg/cm 2 of muscle cross-sectional area [number of myofibrils]. Cross sectional area of the quadriceps of world class weight lifter- 150 cm 2 – 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 Physiology3

4 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 Physiology4

5 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 minutes1700 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 Physiology5

6 Ability to remain active for a long period. Related to the nutritive support for the muscle Exercise Physiology6 Diet Endurance- Min. Glycogen- g/kg High carbohydrate24040 Mixed12020 High fat856

7 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 Physiology7

8 Exercise Physiology8

9 Exercise Physiology9

10 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 Physiology10

11 Exercise Physiology11

12 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 Physiology12

13 Fast-twitchSlow-twitch Large in diameter [2 times]Less in diameter Phosphagen and glycogen- lactic acid enzyme more active [2-3 times] More mitochondria, myoglobin and enzymes for aerobic metabolism Less capillariesMore capillaries Deliver extreme amounts of power for short periods. Provide endurance Exercise Physiology13

14 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 Physiology14 FastSlow Marathoners1882 Swimmers2674 Average male5545 Weight lifters5545 Sprinters6337 Jumpers6337

15 Oxygen consumption [ml/min] under maximal conditions: –Untrained average male3600 –Athletically trained male4000 –Male marathon runner5100 Relation between oxygen consumption and pulmonary ventilation is linear. Limits of pulmonary ventilation L/min: –Maximal exercise ventilation –Maximal breathing capacity Exercise Physiology15

16 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 exercise48 –Speed skaters on maximal exercise64 –Swimmers on maximal exercise71 –Oarsman on maximal exercise Exercise Physiology16

17 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 Physiology17

18 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 Physiology18

19 Exercise Physiology19

20 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 exercise23 –Marathoner at maximal exercise Exercise Physiology20

21 In marathoners, –Volume of chambers increase by 40 % –Heart mass increase by 40 % Exercise Physiology21 Stroke Volume (ml) Heart Rate (beats/min) Resting nonathlete75 Resting marathoner10550 Maximum- nonathlete Maximum-marathoner162185

22 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 °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 Physiology22

23 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 Physiology23

24 Increases performance by staircase phenomenon Exercise Physiology24

25 Starling law of relationship to initial length to the force generated Exercise Physiology25

26 High carbohydrate diet vs high fat diet ? Protein intake Vitamins and minerals Exercise Physiology26

27 Facilitate heat loss Exercise Physiology27

28 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 Physiology28

29 Prof K. Sivapalan Department of Physiology, Faculty of Medicine, University of Jaffna

30 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 Physiology30

31 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 Physiology31

32 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 Physiology32

33 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 Physiology33

34 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 Physiology34

35 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 Physiology35

36 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 Physiology36

37 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 Physiology37

38 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 Physiology38

39 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 Physiology39

40 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 Physiology40

41 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 Physiology41

42 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 Physiology42

43 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 Physiology43

44 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 GnRH pulsatility 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 Physiology44

45 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 Physiology45

46 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 Physiology46

47 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 year group was capable of converting physical activity into health benefits in both the short and long term Exercise Physiology47

48 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 Physiology48

49 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 Physiology49

50 Exercise Physiology50

51 Exercise Physiology51


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