Chapter 3

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•large nutrients digested into smaller, usable fuelscarbohydrates glucosefats (triglycerides) fatty acidsproteins 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

•primary form is glucose•transported to muscle (and other tissues) via blood•stored in liver and muscle as glycogen•ATP produced more quickly from CHO than from fats or proteins•CHO stores can be depleted

Carbohydrates

•stored in adipose tissue and in muscle•muscle uses fatty acids for fuel•produce ATP more slowly than CHO•during rest, provides >½ the ATP, but little during intense exercise•fat stores not depletable

Fats (triglycerides)

•split into amino acids in gut, absorbed, and transported by blood•primary role is providing building blocks for metabolic functions and tissue building•provides 5-15% of fuel for ATP production

Proteins

•muscles have small ATP storage capacity•3 energy systems produce ATP

aerobic – primary system for endurance eventsanaerobic – primary system for speed events“immediate” – primary system for power events

•systems may work simultaneouslydepends upon exercise intensity and duration

•Aerobic system takes 2-3 min to fully activate•Anaerobic system takes ~5 s to fully activate•Immediate system can provide ATP immediately

At onset of exercise, three systems are used continuously, though contribution of the three systems change with time.

Ability of the Cardiovascular system to deliver oxygen rich blood to body tissues.

Muscles ability to process and utilize oxygen to produce energy.

Measure VO2max via spirometry / graded exercise

stress test Estimate

Sub-maximal graded exercise test Step test

Based on the fact that individuals with higher SV will recover faster

Recovery HR will be lower in individuals w/ higher VO2max

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Rest BeginExercise

1 min 2 min EndExercise

1 min 2min

Sedentary

Trained

Elite Athlete

Initial level of cardiovascular fitness

Frequency of training Duration of training Intensity of training Specificity of training

Lower initial fitness level allows more room for improvement

Generally “average” individual can expect 5-25% improvement w/ 12 weeks of training

Everyone has GENETIC Limit Some people are genetically more

gifted and/or respond better to training

Generally recommended: at least 3 X’s/week

Training 4 or more days per week results in only small increases in VO2max

Weight control: 6 or 7 days/week recommended

Continuous (Long Slow Distance) 70-90% of HR max Less taxing on individual

Interval Training Repetitive exercise intervals separated

by rest intervals Exercise Interval: 90% HR max Rest interval: 3X’s as long as exercise

(3:1 ratio)

Most critical factor in training May be expressed as:

% of VO2max

Heart rate or % of maximum HR

METS (metabolic equivalents) Rating of Perceived Exertion (RPE) Calories per unit time

Threshold for aerobic improvement At least 50-55% of VO2max

70%+ of age predicted max HR (220-age) Often referred to as “conversational

exercise” Overload will eventually become

average activity Must increase intensity / duration to

continue improvement in CV endurance

At least 3X’s per week 30 – 60 minutes Continuous, large muscle mass

exercises Expend at least 300kcals per

session 70% of age predicted max HR

Start slowly Much higher risk of injury before adaptation

occurs Warm Up (50-60% Max HR)

temp. of & blood flow to muscle Gentle stretching

Dress for the weather Cool Down

Increases lactic acid removal Gentle stretching

Fatigue Predominates at higher intensities – less able to

clear With improved fitness – better able to tolerate

lactic acid build up

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

Segal KR et al. Am J Clin Nutr. 1984;40:995-1000.

Thermic effect of feeding

Energy expenditure of physical activity

Resting energy expenditure

Sedentary Person (1800 kcal/d)

Physically Active Person

(2200 kcal/d)

8%8% 17%17%

75%75%

8%8%

60%60%

32%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

•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.

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)

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)

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: ______________________

Chapter 9

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