Chapter 2: Exercise Physiology. PE 254. Overview of Energy Metabolism. large nutrients digested into smaller, usable fuels carbohydrates glucose fats ( triglycerides ) fatty acids proteins amino acids
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Overview of Energy Metabolism • large nutrients digested into smaller, usable fuels • carbohydrates glucose • fats (triglycerides) fatty acids • proteins amino acids • blood delivers fuels to muscle which transforms them into ATP (adenosine triphosphate) • ATP is the universal “currency” used by tissues for energy needs • food + O2 ATP + CO2 + H2O + heat
Effect of Exercise Intensity on Metabolism http://www.youtube.com/watch?v=VE_W1ghtMMg
Lactic Acid – anaerobic breakdownproduct of pyruvate • Fatigue • Predominates at higher intensities – less able to clear • With improved fitness – better able to tolerate lactic acid build up
Ways to Measure Energy Expenditure • Direct calorimetry: Transfer of body heat to water. • Indirect calorimetry: Measure of V02 uptake • Convert V02 to kilocalories: Use caloric equivalent of O2 (4.7-5.0 kcal . L–1); for every liter of oxygen consumed, you burn 5 kcal (calories)
Maximal Oxygen Uptake ALSO CALLED: • VO2 max • Peak aerobic power • Maximal aerobic power • Maximum voluntary oxygen consumption • Cardio-respiratory aerobic capacity • Maximal cardio-respiratory fitness • Maximal functional aerobic capacity
VO2 Max • A maximum rate at which an individual can consume O2 during maximal exertion. • Expressed as the maximum volume of oxygen consumed/min • Absolute: litres per min (L/min) • Relative: milliliters per kilogram per minute (ml/kg/min)
VO2 Max Depends On • 3 systems: Pulmonary, Cardiovascular, Muscular • Cardiac output: stoke volume, heart rate, peripheral resistance • Muscle blood flow: capillary density • Hemoglobin content (oxygen-carrying red pigment of the red blood corpuscles) • Muscle mass • Muscle fiber type (e.g., Type I or Type II) • Oxygen extraction: muscle mitochondrial density, oxidative enzymes • Pulmonary function
Calculating VO2max The formulas: • Male: 108.844 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)] • Female: 100.5 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)]
Activity: Problem Solving • Emma weighs 145 pounds. She jogged her mile in 14 minutes and 45 seconds, which is 14.75 minutes. Her heart rate at the end of the mile was 163 bpm. Find Thelma’s VO2max. VO2max = ______________________ ml/kg/min. The formulas: • Male: 108.844 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)] • Female: 100.5 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)]
Problem Solving • Emma weighs 145 pounds. She jogged her mile in 14 minutes and 45 seconds, which is 14.75 minutes. Her heart rate at the end of the mile was 163 bpm. Find Emma’s VO2max. • Female: 100.5 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)] VO2max = 37.08 ml/kg/min.
Problem Solving • What was Emma’s caloric expenditure? VO2max = 37.08 ml/kg/min. Caloric Expenditure (kcal/min) • Multiply the VO2 value in ml/kg/min by the client’s weight in kilograms. VO2 x body weight in kilograms(kg) – Emma’s weight: 65.9kg You will be left with a VO2 value in ml/min. 2443.6 ml/min. • Divide this value by 1,000 to convert VO2 to L/min. 2.44 L/min. VO2 (in ml/min) / 1,000 Take this Value and multiply by 5kcal/L. 12.2 kcal/min. • (1) For every Liter of Oxygen consumed, you burn 5 kcal (calories) • (2) You now have Calories burned/minute (a) Multiply by 60 for Calories burned/hour (b) Multiply by number of minutes exercised or exercising for. 180 calories burned in 14 minutes and 45 seconds.
Basal Metabolic Rate Your basal metabolic rate, or BMR, is the minimum calorific requirement needed to sustain life in a resting individual. It can be looked at as being the amount of energy (measured in calories) expended by the body to remain in bed asleep all day! BMR can be responsible for burning up to 70% of the total calories expended, but this figure varies due to different factors (see below). Calories are burned by bodily processes such as respiration, the pumping of blood around the body and maintenance of body temperature. Obviously the body will burn more calories on top of those burned due to BMR.
Components of Daily Energy Expenditure Thermic effect of feeding Energy expenditure of physical activity Resting energy expenditure 8% 17% 8% 32% 75% 60% Sedentary Person (1800 kcal/d) Physically Active Person (2200 kcal/d) Slide Source: www.obesityonline.org
Energy Needed for Activity • Calorimetry gives energy needed for various levels of activity. Energy expenditures above basal: • Eating, reading 0.4 Cal/kg-h • Doing laundry 1.3 • Cello playing 1.3 • Walking slowly 2.0 • Walking 4 mph 3.4 • Swimming 2 mph 7.9 • Crew race 16.0
Basal Metabolic Rate • It takes energy just to stay alive. • Basal metabolic rate, or BMR • For warm-blooded animals, most energy used • to maintain body temperature. • Human BMR: 1.0 Cal/kg-h • Example: m = 70 kg, 24 hour day • Basal metabolism = 1.0 Cal/kg-h * 70 kg * 24 h/day • =1680 Cal/day • This does not account for any activity.
Figuring total caloric needs: One 75 kg person’s day Basal metabolism 1.0 Cal/kg-h * 24 h * 75 kg = 1800 Cal Reading, writing, talking, eating, 12.5 h 0.4 Cal/kg-h * 12.5 h * 75 kg = 375 Cal Walking slowly, 1 h 2.0 Cal/kg-h * 1 h * 75 kg = 150 Cal Playing cello, 1.25 h 1.3 Cal/kg-h * 1.25 h * 75 kg = 120 Cal Energy needed for digestion 2500 Cal consumed * 8% = 200 Cal Total needs: 2645 Cal
Total Daily Energy Expenditure Solving for moderate exercise activity total daily energy expenditure (TDEE) TDEE (moderate) = 1.55 x BMR
Activity: Calculating BMR Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm) - (6.8 X age) Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) - (4.7 X age) Note: 1 inch = 2.54 cm.1 kilogram = 2.2 lbs. Example: You are femaleYou are 30 yrs oldYou are 5' 6 " tall (167.6 cm)You weigh 120 lbs. (54.5 kg)Your BMR = 655 + 523 + 302 - 141 = 1339 calories/day
Activity Multiplier Sedentary = BMR X 1.2 (little or no exercise, desk job)Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)Extr. active = BMR X 1.9 (hard daily exercise/sports & physical job or 2X day training, i.e marathon, contest etc.) Example: Your BMR is 1339 calories per dayYour activity level is moderately active (work out 3-4 times per week)Your activity factor is 1.55Your TDEE = 1.55 X 1339 = 2075 calories/day Determine the energy cost: ______________________
Hot Weather and Heat Stress • Dehydration = excessive loss of fluid • Heat cramps = sudden development of muscle spasms and pain • Heat exhaustion = heat illness related to dehydration from exertion in hot weather • Heat stroke = a severe and often fatal heat illness characterized by significantly elevated core body temperature
Heat Illness • Above a core temperature of 103 degrees Fahrenheit: weakness, vomiting, headache. This is a medical emergency. • At about 104 degrees: heat stroke. Confusion, dehydration. Seizure possible. • Above 105 degrees: delirium. If not treated immediately, internal organs will begin to fail. • Above 106 degrees: convulsions. • Above 107 degrees: coma. • Above 108 degrees: death.
Preventing Heat Illness • Use caution in high heat or humidity (over 80°F and/or 60% humidity); lower your intensity and/or add rest breaks • Exercise morning or evening • Drink plenty of fluids; check weight before and after exercise • Avoid supplements and beverages containing stimulants • Wear clothing that “breathes” • Slow down or stop if you feel uncomfortable
Heat Stroke Deaths in Football 'All Preventable' By Dan Peterson, LiveScience's Sports Columnist posted: 02 February 2009 08:29 am ET Last Monday, first-year Kentucky high school football coach David Jason Stinson pleaded not guilty to charges of reckless homicide in the death of Max Gilpin, a 15-year-old offensive lineman. Gilpin collapsed Aug. 20 while running sprints with the team on a day when the heat index reached 94 degrees. The case could signal a landmark shift in the expectation for how coaches deal with struggling players on a hot day. Gilpin's body temperature was 107 degrees when he reached the hospital and he died three days later from heat stroke. The risks of heat-related diseases to athletes, both young and old, are always present but the warning signs are often hidden. Since 1995, 33 football players have died from heat stroke, according to an annual report from the University of North Carolina. Frederick O. Mueller, professor of exercise and sports science at UNC and the author of the report, calls the figure unacceptable. "There's no excuse for any number of heat stroke deaths, since they are all preventable with the proper precautions," Mueller said.
Exercise in Cold Weather • Hypothermia = low body temperature due to exposure to cold conditions • Frostbite = freezing of body tissues characterized by pallor (paleness), numbness, and a loss of cold sensation • Prevention: • Don’t stay out in very cold temperatures (consult wind chill values) • Wear appropriate clothing
Poor Air Quality • Poor air quality can decrease exercise performance; it especially affects those with respiratory problems • Do not exercise outdoors during a smog alert or if air quality is poor