Transcript Msmt Energy Expenditure - Weber State University

Measuring and Evaluating
Energy Expenditure
McArdle, Katch, & Katch
Chapter 7
Overview of Energy
Transfer during Exercise
Overlapping area
represents generality.
 For each energy
system, specificity
exceeds generality.
 Effects of exercise
training remain highly
specific.

Overview of Energy
Transfer during Exercise



At initiation of high- or lowspeed movements,
intramuscular phosphagens
provide immediate and
nonaerobic energy.
After first few seconds,
glycolytic energy system
provides greater proportion of
total energy.
Continuation, places greater
demand on aerobic pathways.
Measuring & Evaluating
Anaerobic Energy Systems
Evaluation of Immediate Energy System
 Measure changes in chemical substances
used or produced
 Quantify amount of external work
performed during short-duration, highintensity activity.
Evaluating Immediate
Energy System
Power = F x D/time
 Muscular short term
power by sprinting up
flight of steps
 Jumping-power tests
may not measure
anaerobic power
because too brief to
evaluate ATP and PCr.

Evaluating Immediate
Energy Systems
Other power tests last 6 to
8 seconds.
 Low interrelationship
among power tests
suggests high degree of
task specificity. The best
sprint runner may not be
the best repetitive
volleyball leaper.

Evaluating Short-Term
Glycolytic Energy System
 Blood
lactate level is most common
indicator of short-term energy system (7.3).
 Glycogen depletion in specific muscles
activated provides indication of contribution
of glycolysis to exercise (figure 7.4).
 Tests demanding maximual work for up to 3
min. best estimate glycolytic power.
Evaluating Short-Term
Energy System
In Katch cycle test peak power
represents anaerobic power &
total work accomplished reflects
anaerobic capacity.
 Wingate test provides peak
power output, average power
output, and anaerobic fatigue.
 What is anaerobic fatigue?

Factors Affecting
Anaerobic Performance

Specific anaerobic
training
 Trained
have more
glycogen depletion than
untrained
 Trained have higher
levels of HLa
 Buffering
capacity
(alkaline reserve)
 Motivation
Measuring & Evaluating
the Aerobic System
Direct Calorimetry.
 Unit to measure heat is calorie. One calorie is
amt. heat necessary to raise the temperature of
one gram of water by 1o Celsius. Kilocalorie
is generally used, 1 Kcal = 1,000 calories.
 Process measuring animal’s metabolic rate
via measurement of heat: direct calorimetry.
Direct Calorimetry
Direct Calorimetry
 Theory: when body uses energy to do work,
heat is liberated.
Foodstuff + Oxygen  ATP + heat

Cell work + heat
Therefore, measuring heat production (calorimetry)
by animal gives a direct measurement of
metabolic work.
Measuring & Evaluating the
Aerobic System
Technique places human in
airtight chamber
(calorimeter) which is
insulated from
environment and
allowance is made for
exchange O2 & CO2.
Body temperature raises
temperature of water 
computer heat production
Measuring & Evaluating the
Aerobic System
Indirect Calorimetry
 Theory. Since direct relationship between O2
consumed & amt. heat produced by body,
measurement of O2 consumption provides
estimate of metabolic rate.
Foodstuffs + O2  Heat + CO2 + H2O
(indirect)
(direct)
 Measurement
of oxygen consumption is
indirect, since heat not measured directly.
Indirect Calorimetry
Closed circuit
spirometry involves
rebreathing same air.
 Open circuit
spirometry involves
breathing atmospheric
air.

Indirect Calorimetry
Open circuit spirometry measures the volume and
samples the air expired for percent of oxygen and
carbon dioxide.
Indirect Calorimetry



Volume of oxygen consumed per minute is
calculated as volume O2 inspired –volume O2
expired.
Inspired VO2 = ventilationI x .2093
Expired VO2 = ventilationE x (% O2 expired)
Indirect Calorimetry
 Volume
of carbon
dioxide consumed per
minute is calculated as
volume CO2 expired –
volume CO2 inspired.
 Expired VCO2 =
ventilationE x (% CO2
expired)
 Inspired VCO2 =
ventilationI x (.03%)
Caloric Transformation
for Oxygen
 Approximately
4.82 kcals release when
blend of CHO, pro, fat burns in 1 L O2.
 Physiological fuel value of @ nutrient is
amount of usable energy per gram nutrient.
 Heat
of combustion
 % digestibility
 Urinary nitrogen loss
 Caloric
value for oxygen varies slightly (w/i
2 – 4 %) with variation in nutrient mixture.
Caloric Transformation
for Oxygen
Food
CHO
Energy Energy
oxygen carbon RQ
calmeter physiologic (kcal/L) dioxide
4.1
4.02
5.05
5.05
1
Pro
5.65
4.3
4.46
5.44
.82
Fat
9.45
8.98
4.68
6.63
.71
4.82
5.89
.82
Mixed
Respiratory Quotient
 Respiratory
quotient (RQ) is ratio of
volume of carbon dioxide produced to
volume of oxygen consumed.
 RQ for Carbohydrate is 1.0.
Glucose C6H12O6 + 6 O2  6 CO2 + 6 H2O
RQ = 6 CO2/ 6 O2 = 1
Respiratory Quotient

RQ for fat is .70
C16H32O2 + 23 O2 
16CO2 + 16 H2O
RQ = 16 CO2 / 23 O2 = .7

RQ for protein is .82
Protein must first be
deaminated in liver.
Resulting “keto acid”
fragments oxidized
requiring O2 > CO2
Respiratory Quotient
RQ for mixed diet is .82
from 40% CHO &
60% fat.
 Non-protein RQ is
between 0.7 and 1.0.
 Thermal equivalents
of oxygen for different
non-protein mixtures.
Respiratory Exchange
Ratio
Respiratory Exchange Ratio is ratio of carbon
dioxide exhaled to oxygen consumed when CO2
and O2 exchange doesn’t reflect food oxidation.
RER ≠ RQ during hyperventilation and exhaustive
exercise. Non-metabolic CO2.
 Exhaustive exercise presents RER > 1.00.
HLa + NaHCO3  NaLa + H2CO3  CO2 + H20
Lactate Buffering by Sodium Bicarbonate.
Measuring Maximal
Oxygen Consumption
The highest maximal
oxygen uptakes
generally recorded for
cross-country skiers,
runners, swimmers,
and cyclists.
 Lance Armstrong VO2
max = 83.3 ml/kg/min

Measuring Maximal
Oxygen Consumption
Criteria for true max
VO2 is leveling off or
peaking in oxygen
uptake.
 Other criteria:

 Oxygen
uptake fails to
increase by some value
 Maximum lactic acid
of 70-80 mg/100 mL
 Maximum predicted
HR or R > 1.0
Measuring Maximal
Oxygen Consumption
Tests of Aerobic Power
 Two general criteria:
 Independent
of muscle strength, speed, body size, skill
 Consists of graded exercise to point of exhaustion
(without muscular fatigue)
Measuring Maximal
Oxygen Consumption

Continuous versus Discontinuous
 Small
differences between continuous & discontinuous
on bicycle, but lower than treadmill tests.
Measuring Maximal
Oxygen Consumption
Commonly used
protocols.
 Vary

 Exercise
duration
 Treadmill speed
 Treadmill grade
Measuring Maximal
Oxygen Consumption

Factors that affect
Maximal Oxygen
Uptake
 Mode
 Heredity
 State
of training
 Gender
 Body composition
 Age
Predicting VO2 Max
Walking & Running
Tests use age, gender,
time for test, HR at
end of test
 Predictions based on
HR: VO2 linearity.
 Similar maximum
HRs for healthy
people.

Illustration References
 McArdle,
William D., Frank I. Katch, and
Victor L. Katch. 2000. Essentials of
Exercise Physiology 2nd ed. Image
Collection. Lippincott Williams & Wilkins.
 Plowman, Sharon A. and Denise L. Smith.
1998. Digital Image Archive for Exercise
Physiology. Allyn & Bacon.
 Axen, Kenneth and Kathleen Axen. 2001.
Illustrated Principles of Exercise
Physiology. Prentice Hall.