Chapter 2: Exercise Physiology

PE 254

• 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

Overview of Energy Metabolism

Relationship Between Energy Expenditure and Work Rate

Interaction of Exercise Intensity and Duration

Three Energy Systems

Three Energy Systems

Effect of Exercise Intensity on Metabolism

http://www.youtube.com/watch?v=VE_W1ghtMMg

Oxygen Deficit and Oxygen Debt

Heart Rate and Pulmonary VentilationResponses to Submaximal Work

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

Effect of Training on Lactate Threshold

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)

Ways to Measure Energy Expenditure

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

Relationship Between HR and VO2

Calculating VO2maxThe 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: 65.9kgYou 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 ExpenditureThermic

effect of feeding

Energy expenditure of physical activity

Resting energy expenditure

Sedentary Person (1800 kcal/d)

Physically Active Person

(2200 kcal/d)

8% 17%

75%

8%

60%

32%

Slide Source: www.obesityonline.org

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

Energy Needed for Activity

•It takes energy just to stay alive.Basal metabolic rate, or BMR

•For warm-blooded animals, most energy usedto maintain body temperature.

•Human BMR: 1.0 Cal/kg-hExample: 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.

Basal Metabolic Rate

Figuring total caloric needs: One 75 kg person’s day

Basal metabolism1.0 Cal/kg-h * 24 h * 75 kg = 1800 Cal

Reading, writing, talking, eating, 12.5 h0.4 Cal/kg-h * 12.5 h * 75 kg = 375 Cal

Walking slowly, 1 h2.0 Cal/kg-h * 1 h * 75 kg = 150 Cal

Playing cello, 1.25 h1.3 Cal/kg-h * 1.25 h * 75 kg = 120 Cal

Energy needed for digestion2500 Cal consumed * 8% = 200 Cal

Total needs: 2645 Cal

Solving for moderate exercise activity total daily energy expenditure (TDEE)

Total Daily Energy Expenditure

TDEE (moderate) = 1.55 x BMR

Activity: Calculating BMR

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

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)

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

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.

Heat Illness

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

Air Quality Index