KIN 240 – Introduction to Kinesiology Physiology of Physical Activity

What is Exercise Physiology? Application of principles of biology and chemistry to understand how the body responds to physical activity How does body respond to immediate demands of being physically active? How does body adapt to repeat bouts of exercise?

What Do Exercise Physiologists Do? Faculty members in colleges/universities Teach courses and conduct research in exercise physiology, anatomy, exercise prescription, sport nutrition Non-academic settings Exercise instructors in commercial/corporate fitness centers Personal trainers, strength & conditioning specialists Cardiac and pulmonary rehabilitation Military and NASA applications Credentials Certifications through ACSM, NSCA, ACE, etc. to enhance academic training

Goals of Exercise Physiology Enhance sport performance and training Application of physiological techniques to understand and improve human exercise performance Impact of flexibility on performance, effects of dehydration in wrestlers Fitness Understanding physiological determinants of physical fitness and how training programs improve fitness Development of recommendations of optimal intensity, frequency and duration of training program for various activities and populations

Goals of Exercise Physiology Promote health Understanding why exercise is beneficial in reducing risk of some diseases Cardiovascular disease and other hypokinetic diseases (Type II diabetes, hypertension, obesity) Understand anatomical and physiological changes from exercise Examination of functional responses and structural adaptations of body systems to different types of physical activity Skeletal muscle, cardiovascular, respiratory, endocrine systems

History of Sub-discipline Early beginnings Krogh (Denmark) developed first cycle ergometer to study physiological response to injury in 1920 Hill (London) studied energy metabolism in 1921 Laboratory settings Karpovich (Springfield College) studied effects of ergogenic aids on physical performance starting in 1927 & founded ACSM Cureton (University of Illinois) established lab in 1944 which has produced many of leading investigators in field

History of Sub-discipline Since 1950 Morris (England) published study in 1953 on hearth disease and physical activity of bus drivers vs. conductors on double-decker buses US government statements in 1990’s Physical activity is major risk factor for cardiovascular disease and moderate levels of physical activity confer significant health benefits (1995) Regular physical activity, in addition to reducing risk of heart disease, reduces risk of diabetes, hypertension and colon cancer and helps control weight (1996)

Research Methods Laboratory work Affords greater opportunity to control factors that can affect response to exercise (temperature, humidity) and to utilize standardized techniques to compare results Many different tools available to assess VO2 max Cycle ergometers, treadmills, arm ergometers, rowing ergometers Usually rely upon prediction equations with given variables vs. true assessment of maximal oxygen uptake Body composition assessed via hydrostatic weighing, bioelectrical impedance, air displacement plethysmography and dual-energy x-ray absorptiometry

Research Methods Laboratory work Biochemical methods Animal models Invasive techniques that require obtaining blood samples and muscle tissue biopsies before and after exercise bouts to study cellular and tissue changes Animal models Allows for study of brain, heart, other organ changes that can’t be studied in humans Allows for study of experimental techniques (e.g. – radioactive isotopes) that can’t be studied on humans Allows greater uniformity of subjects and environment

Research Methods Field work Use of non-laboratory based assessments to gauge fitness elements – obvious limitations vs. lab settings Walk-run tests done to estimate VO2 max Heart rate monitors (POLAR units, devices on most fitness center cardiorespiratory exercise equipment Pedometers and accelerometers used throughout day/week to assess physical activity intensity/duration Skinfold calipers used to assess body composition

Overview of Knowledge Skeletal muscles Muscle fiber types Fast-twitch vs. slow-twitch muscle fibers Energy sources – knowledge allows for specificity of training ATP-phosphocreatine system High-intensity exercise bouts for short time periods (<15 seconds) Anaerobic glycolytic system Longer durations exercise bouts (1-2 minutes), lactic acid build up as byproduct of system Aerobic system Lower intensity exercise bouts for longer time periods

Overview of Knowledge Skeletal muscles Resistance training Muscular strength – maximal force exerted by muscle/s Muscular power – product of force x speed of movement Muscular endurance – ability to repeatedly exert force over prolonged time period Muscular hypertrophy – increase in size of muscle fibers No human research evidence of increased number of muscle fibers (hyperplasia) Types of exercise Isometric (no movement), isotonic (muscle changes length – concentric & eccentric contractions) and isokinetic (muscle changes length at constant rate of velocity)

Overview of Knowledge Cardiovascular system Cardiac output – amount of blood pumped out of heart each minute Stroke volume – amount of blood pumped per heart beat Blood flow distribution – to brain and internal organs at rest, shifts to skeletal muscles during exercise Adaptations to training Endurance training increases size and efficiency of contraction of heart muscle – leads to increased stroke volume and cardiac output Grade exercise tests allow for assessment of baseline status and for evaluation of training program effectiveness

Overview of Knowledge Respiratory system Regulates exchange of gases between external environment and internal environment (body/lungs) Minute volume is amount of air exhaled per minute Product of tidal volume (amount of air exhaled per breath) and number of breaths per minute Maximal ventilation (amount of air entering and leaving lungs) increases with exercise

Overview of Knowledge Nutritional intake and exercise Carbohydrates Stored as glycogen in muscles and liver + blood glucose – available as energy source Low blood sugar associated with early fatigue Muscle glycogen stores depleted within 90 minutes of continuous exercise Diet with appropriate amount of carbohydrates will allow blood glucose to be optimized and maintained and for maintenance/replenishment of glycogen stores following exercise bouts

Overview of Knowledge Nutritional intake and exercise Fluid intake Failure to adequately maintain and replace fluids lost via sweat during exercise can impair performance and increase risk of heat related injuries Sweat loss decreases plasma volume and increases body temperature Must pre-hydrate prior to exercise, consume adequate liquids during exercise and re-hydrate following exercise Iron intake Iron allows body to make hemoglobin which allows for transport of oxygen via circulatory system Low iron intake can result in anemia – feeling fatigued

Overview of Knowledge Physical activity, fitness and health Strenuous exercise programs not needed to gain health benefits Recommended to accumulate 30 minutes of moderate intensity (brisk walk, moderate cycling, moderate swimming, etc.) physical activity most, if not all, days of the week – doesn’t have to be continuous Greater volumes and intensity of exercise result in additional health and fitness benefits To improve cardiorespiratory endurance, recommended to do 20-60 minutes of physical activity 3-5 days/week at 70-94% maximal heart rate

Overview of Knowledge Physical activity, fitness and health Effects of age VO2 max decreases with age but decreases less for physically active individuals vs. sedentary individuals Coronary artery disease Individuals who are physically active/fit have less risk of cardiovascular disease and some cancers Weight management When caloric intake exceeds caloric expenditure, excess calories are converted to fat and stored in body