Noël Konken
Work Metabolism (KNR 481)
Laboratory - Assessment of Oxygen Consumption
DUE DATE:
December 2, 2015.
RATIONALE:
The ability to consume oxygen is important for the metabolic function of body cells. Cell activity is dependent
upon oxygen because the cell derives its energy from adenosine triphosphate (ATP), which is produced mainly
by aerobic metabolism. Aerobic metabolism produces large volumes of ATP via oxidative pathway. This
pathway reflects the ability of the muscles' mitochondria to synthesize the phosphagen ATP. The maximal
consumption of oxygen is dependent not only on the cell's ability to extract and use oxygen, but also on the
ability of the cardiovascular system and respiratory system to transport this oxygen to the cell. With respect to
the cardiovascular system, the transport of oxygen is represented by the cardiac output, the amount of blood
pumped by a heart ventricle per minute. Thus, a greater cardiac output leads to a greater maximal oxygen
consumption under normal conditions. The respiratory system's transport of oxygen is represented by ventilation,
which is measured as liters of air per minute. Reference - Adams (1990).
PURPOSE:
To gain knowledge and understanding of the concept of exercise oxygen consumption, maximal oxygen
consumption, oxygen deficit/debt and to gain experience in oxygen consumption measurement.
METHODS AND PROCEDURES:
With the use of a volunteer, use a multistage continuous treadmill test with the on-line metabolic data analysis
system to determine the subject’s oxygen consumption responses.
Part I. Subject Characteristics.
Record the subject’s physical characteristics (age, ht & wt).
*Information Not Available*
Part II. Resting Analysis.
 Have subject positioned in a quiet “resting” state for approximately 5 minutes.
 Measure the metabolic responses to this activity using oxygen consumption analysis.
1) Determine resting metabolism via oxygen consumption analysis.
With an average energy expenditure of ~1.63kcals/min during rest, the resting metabolism via
oxygen consumption during the time of rest is 6.8 kcals.
2) Determine resting metabolism via BSA calculation.
Information not available due to lack of data (height, weight)
3) Determine resting metabolism via Reference table in the text.
Information not available due to lack of data (height, weight)
Questions:
4) How do these metabolic responses compare across these three techniques?
Comparison cannot be determined due to incomplete data
5) How do you explain the differences observed between the techniques?
There are various possibilities for why the data could be different between the three techniques. It
can be inferred resting metabolism via oxygen consumption will be slightly higher than the BSA
calculation and reference table due to the environment. Although the subject was sitting in a chair, it
is difficult to infer the subject was truly at rest due to varying causes that are associated with being in
a lab, such as lab anxiety, the nervousness while being observed by peers, or restlessness. Such
environmental factors would increase resting energy expenditure by increasing heart rate, stress
levels, or other metabolic processes.
Part III. Steady State Exercise.
 Have subject warmup and exercise for approximately 3 minute stages.
 Measure the changes in metabolism via oxygen consumption analysis data.
6) Graph the oxygen consumption and carbon dioxide kinetics from rest to warmup to exercise stages.
7) Determine if steady state is achieved for each stage of exercise.
Because we can see a relatively flat line for VO2 in all three stages of exercise, it can be concluded
steady state is reached for all stages of exercise tested. The steady state is strongest during the rest
phase with the strongest plateau of VO2 around 0.3 L/min. There is a clear transition period from
the rest to warm-up phase at the 4.2 minute mark; however, we see steady state quickly regained
during the warm-up phase by the 5 minute mark with a consistent VO2 value around 2.2 L/min. The
transition between the warm-up and exercise phase is not as drastic, and steady state is maintained
during exercise quickly after the transition with a consistent VO2 value around 2.6 L/min.
8) Determine the energy expenditure for each stage of exercise.
Average kcals/min
Total Energy Expenditure (kcals)
Resting Phase
1.63
6.8
Warm-up Phase
8.72
27.0
Exercise Phase
12.4
112.4
9) Determine the percentage of kcals from carbohydrates and fats used for each stage of exercise.
Avg. RQ
% kcals from CHO
% kcals from Fat
0.87
57.5
42.5
Resting Phase
Warm-up Phase
0.82
40.3
74.1
Exercise Phase
0.92
74.1
25.9
10) Calculate how many grams of carbohydrate and fat were used for each stage of exercise.
CHO (g)
Fat (g)
0.98
0.32
Resting Phase
Warm-up Phase
2.72
1.79
Exercise Phase
20.82
3.23
Questions:
11) What is steady state oxygen consumption?
Steady state O2 consumption is when the body can rely solely on the aerobic system of metabolism
to provide the body with ATP. During steady state, aerobic glycolysis is operating, but the lactate
produced is not contributing ATP; it is either oxidized or reconverted to glucose. Steady state O2
consumption can be displayed as a flat line plateau of an O2 consumption curve.
12) What is oxygen deficit?
Oxygen deficit is a quantitative measurement used to express the difference between total oxygen
consumption during physical activity and total oxygen consumed if steady state oxygen consumption
was achieved at the direct onset of activity.
13) Is oxygen deficit the same for different intensities of exercise?
No, oxygen deficit is not the same for different intensities of exercise. The intensity of an exercise
activity effects the transition phase from rest to activity and amount of oxygen consumed (VO2)
during work. As intensity increases, both the transition period and VO2 increase; thus creating a
larger oxygen deficit. In sum, there is a direct relationship between exercise intensity and oxygen
deficit.
14) What factors affect the oxygen deficit?
The leading factor that affects oxygen deficit among individuals is ones endurance capability. An
endurance-trained individual will have a lower oxygen deficit than sprint-power athletes, untrained
individuals, older adults, and patients with cardiac problems. This means endurance athletes achieve
steady rate more rapidly with a faster aerobic kinetic response that allows them to consume a greater
total amount of oxygen to steady state exercise; thus the anaerobic component of energy transfer is
smaller. The reasoning for this rate of aerobic metabolism that decreases endurance-trained athlete’s
oxygen deficit is (1.) more rapid increase in muscle bioenergetics, (2.) Increase in overall cardiac
output, and (3.) disproportionally large regional blood flow to active muscle complemented by
cellular adaptations.
Additionally, aside from the health/fitness of the subject, oxygen deficit can be affected by the
intensity of the exercise, and if the individual as had an adequate warm-up or not.
Part IV. Maximal Exercise.
 Have subject continue to exercise using a progressive intensity every 3 minutes to the point of volitional
exhaustion.
 Measure the changes in metabolism via oxygen consumption analysis data.
15) What are the criteria for a true test of VO2 max?
The primary criteria for determining if a true test of maximal oxygen consumption is obtained is
observing a plateau in oxygen consumption while exercise intensity continues to increase.
Additionally, the secondary criteria include a respiratory exchange ratio measuring >1.0-1.15, lactate
levels measuring >8 mM, age predicted maximal heart rate (220-age), and the individuals selfreported exertion level of >8 or 9
16) Was maximal oxygen consumption attained?
No, maximal oxygen consumption was not attained because the subject completed a simple fuel test.
The subject did not reach max.
17) What is this subject’s absolute VO2 max?
Although we cannot determine absolute VO2 max, the subjects peak VO2 was measured as 3.314
L/min in the data set.
18) What is this subject’s relative VO2 max?
The subject’s relative VO2 max cannot be determined due to lack of data (weight)
19) What is the subject’s fitness classification?
The subject’s fitness classification cannot be determined due to lack of data (weight & age)
Questions
21) Why is VO2 max considered to be the telling indicator of physical fitness??
VO2 max is a useful indicator of physical fitness because attaining a high VO2max has important
physiological meanings. VO2 max depends on the function capacity of the oxygen transport system
which is associated with pulmonary ventilation, hemoglobin concentration, aerobic metabolism, and
blood volume and cardiac output. In obtaining a high VO2 max, one must have a high-level
response of these physiological support systems.
22) What is the Fick equation??
The Fick equation expresses the relationships among cardiac output, oxygen consumption, and the
average difference between the oxygen content of arterial and
mixed-venous blood. The Fick equation requires complex
methodology and can usually only be utilized in a hospital.
23) What is meant by anaerobic threshold??
Anaerobic threshold is the level of exercise intensity in which rate of lactate generation exceeds rate
of lactate removal. This results in a build-up in blood lactate. High intensity activities are often
associated with this build-up of blood lactate. Additionally, untrained athletes are likely to have a
lower anaerobic threshold than trained athletes.
24) What is meant by the lactate threshold??
Lactate threshold describes the highest oxygen consumption or exercise intensity that can be
achieved with less than a 1.0 mM increase in blood lactate concentration above an individual’s preexercise level. This 1.0 mM increase is equivalent to an increase in 9.0 %volume of whole blood.
Lactate threshold is useful in determining intensity for training and racing in endurance sports and
varies between individuals with different endurance capabilities.
Questions:
25) What is oxygen debt?
Oxygen debt is associated with the recovery phase of physical activity in that after exercise,
individuals have an elevated oxygen consumption. This elevated oxygen consumption represents the
cost of repaying for the debt of the oxygen deficit.
26) Is oxygen debt the same for different intensities of exercise?
Oxygen debt is not the same for different intensities of exercise. Increasing exercise intensity is
associated with an increased oxygen deficit due to an increase in VO2 and transition period, and the
larger the oxygen deficit, the larger the energy debt.
27) What factors affect the oxygen debt?
Exercise intensity, opposed to exercise duration, is the leading factor that affects oxygen debt.
Because oxygen debt is depended on oxygen deficit, factors that affect oxygen deficit indirectly
affect oxygen debt, such as the health/fitness of the individual.
28) What is excess post exercise oxygen consumption??
Excess post exercise oxygen consumption is a measurably increased rate of oxygen intake following
exercise intended to ease the body from the oxygen deficit. After engaging in physical activity,
oxygen consumption does not immediately return to resting levels, but follows a logarithmic curve,
decreasing by about 50% over each subsequent 30 second period.