Sports Physiology Prof. Dr. Bayram Yılmaz Yeditepe University Faculty of Medicine Department of Physiology

Muscle strength Pulmonary ventilation Cardiac output 11% difference in performance in women Body fat distribution Estrogen increases deposition of fat in female 27% body fat in female, 15% in male Anabolic effects of testosterone Female and Male Athletes

Power of muscle Strength Holding strength is about 40% greater than contractile strength Endurance Supply of nutrients Amount of glycogen stored Muscles in Exercise

Phosphocreatine-creatine system Glycogen-lactic acid system Aerobic system Muscles Metabolic Systems in Exercise

1) ATP and Phosphocreatine-creatine system are also called phosphagen energy system These together provide maximal muscle strength for 8 to 10 seconds 2) Glycogen-lactic acid system: ( min) Initial stage is glycolysis, anaerobic metabolism Glycose – pyruvic acid – mitochondria – ATP formation When there is insufficient oxygen, pyruvic acid is converted to lactic acid – diffuses out of cell and enters blood Muscles Metabolic Systems in Exercise

3) Aerobic system: Muscles Metabolic Systems in Exercise

Energy Systems in Various Sports

Energy from glycogen-lactic acid system can be used to reconstitute both phosphocreatine and ATP Reconstitution of lactic acid – removal of excess lactic acid 1) A small portion is converted back to pyruvic acid and then metabolized oxidatively 2) Remaining lactic acid is reconverted into glucose in the liver Recovery of Muscle After Exercise

Oxygen debt: The body contains about 2 lt of stored oxygen 0.5 lt in the air of lungs 0.25 lt dissolved in the body fluids 1 lt combined with Hg 0.3 lt in muscle fibers (myoglobin) In heavy exercise, the stored O2 is used in a minute or so for aerobic mechanism = 11.5 lt O2 debt Recovery of Aerobic System After Exercise

Recovery of Muscle Glycogen

Nutrients Used During Muscle Activity

Muscle hypertrophy Effect of Athletic Training on Muscles and Muscle Performance

Fast Twitch and Slow-Twitch Muscle Fibers 1. Fast-twitch fibers are about twice as large in diameter. 2.The enzymes that promote rapid release of energy from the phosphagen and glycogen-lactic acid energy systems are two to three times as active in fast-twitch fibers as in slow-twitch fibers, thus making the maximal power that can be achieved for very short periods of time by fast-twitch fibers about twice as great as that of slow-twitch fibers. 3.Slow-twitch fibers are mainly organized for endurance, especially for generation of aerobic energy. They have far more mitochondria than the fast-twitch fibers. In addition, they contain considerably more myoglobin, a hemoglobin-like protein that combines with oxygen within the muscle fiber; the extra myoglobin increases the rate of diffusion of oxygen throughout the fiber by shuttling oxygen from one molecule of myoglobin to the next. In addition, the enzymes of the aerobic metabolic system are considerably more active in slow-twitch fibers than in fast-twitch fibers. 4.The number of capillaries is greater in the vicinity of slow-twitch fibers than in the vicinity of fast-twitch fibers.

Normal O 2 consumption is 250 ml/min for men Untrained average men: 3600 ml/min Athletically trained men: 4000 ml/min Men marathon runner: 5100 ml/min Respiration in Exercise

Effect of training on VO 2 Max: rate of oxygen usage under maximal aerobic metabolism is VO 2 Max Respiration in Exercise

Blood oxygen gases during exercise Effect of smoking on pulmonary ventilation in exercise Nicotine constricts terminal bronchioles Irritation causes fluid secretion Nicotine paralyzes the cilia, failure of removal of excess fluid and foreign substances Respiration in Exercise Oxygen diffusion capacity of athletes

Cardiovascular System in Exercise Muscle blood flow

Cardiovascular System in Exercise Cardiac output Effect of training on heart hypertrophy and on cardiac output Role of stroke volume and heart rate in increasing the cardiac output

Cardiovascular System in Exercise Cardiac output

Cardiovascular System in Exercise Relation of Cardiovascular Performance to VO2 Max

Body Heat in Exercise Heatstroke

Body Fluids and Salt in Exercise Body fluids and salt in exercise Replacement of NaCl and K

Drugs and Athletes Caffeine can increase athletic performance by about 7% Androgens are powerful anabolic drugs Amphetamines and cocaine have been claimed to increase athletic performance