Energy consumption during various exercises and activity.

1. ERGONOMIC ASPECT OF
EXERCISE ON OXYGEN
AAKANKSHA BAJPAI
MPT

2. PREDICTION OF EXERCISE ENERGY
EXPENDITURE WITH METABOLIC
EQUATIONS
 The capability to accurately estimate energy
expenditure during exercise is a fundamental aspect of
exercise physiology, with fitness professionals
frequently relying on metabolic equations to prescribe
exercise intensity and to determine the energy
expenditure of different exercise modalities.
 Metabolic equations for the prediction of energy
expenditure during common exercise modalities are
presented in Table given below:-

4. OXYGEN CONSUMPTION
 Volume of oxygen consumed, or VO2, is a measure of
the overall total body oxygen consumption or use.
 VO2max represents the maximal rate of oxygen
consumption during exercise testing to volitional
fatigue.
 The higher the VO2max score, the greater the amount
of oxygen utilization and capacity for physical work.
 Oxygen consumption can be represented in both
absolute and relative terms.

5. ABSOLUTE VO2
 Absolute VO2 represents the total amount of oxygen
consumed by the entire body regardless of body size
or weight.
 The standard measurement unit for absolute VO2 is
L/min or mL/min.
 If the absolute amount of oxygen consumed is
measured, the number of calories expended can be
determined.

6.  For example, if a person running on a treadmill is
estimated to have an absolute VO2 of 2.5 L/min, this
translates to 12.5 kcal/min, and if this person
maintained that pace for 20 minutes, he or she would
expend a total of 250 kcal.
These values were calculated as follows:
 1 L oxygen/min = 5 kcal
 2.5 L/min = 5 kcal/L × 2.5 = 12.5 kcal/min
 12.5 kcal/min × 20 minutes = 250 kcal

7. RELATIVE VO2
 ml per kg body weight per min (ml/kg-1/min-1)
 „Used to compare VO2 among varying body sizes.
 For example, if Gary has a VO2max score of 3.5 L/min
and weighs 176 lb (80 kg), his relative VO2 can be
calculated as:
3.5 L/min × 1,000 = 3,500 mL/min
3,500 mL ÷ 80 kg = 43.8 mL/kg/min

8. RESPIRATORY EXCHANGE RATIO
 The amount of oxygen used during metabolism
depends on the type of fuel being used. Because
different fuels produce differing amounts of carbon
dioxide relative to the amount of oxygen consumed,
this can be represented as a ratio.
 This ratio is commonly referred to as the respiratory
exchange ratio (RER) and is calculated from the
volumes of both gases measured at the lungs.
 The respiratory quotient (RQ) is considered a
measure of the same ratio, but it is considered a
reflection of true cellular respiration (i.e., fuel use for
metabolism at the cellular level).

9.  RER ratios for fats and carbohydrates range between
0.70 and 1.00.

11. OXYGEN KINETICS
 Oxygen uptake into muscle cells increases rapidly
during the first few minutes of exercise, reaching a
plateau that generally takes between 45 seconds and 4
minutes to achieve after the onset of activity. This
plateau is described as steady-state and is defined as
the balance between the energy required by working
muscles and the rate of aerobic ATP production.
 The time frame to reach steady-state varies
considerably, depending on the magnitude of the
increment in exercise intensity, conditioning level of the
individual, and the modality of exercise.

12.  For example, the transition from rest to steady-state will
be attained rather quickly when the exercise workload is
low; conversely, it may take upward of 4 to 5 minutes to
achieve steady-state at greater intensities.
 Modalities involving upper and lower extremities (e.g.,
running versus cycling) or modalities with which the
individual has less biomechanical efficiency may extend
the time needed to reach steady-state.

13. OXYGEN DEFICIT
 Oxygen deficit refers to the difference between oxygen
uptake and the oxygen demand of exercise during
exercise conditions that are non–steady-state. Until
steady-state is achieved, the additional energy
demands of the muscles are met by the anaerobic
pathways.
 This creates an energy deficiency, or oxygen deficit.
 The energy supplied for exercise is not simply the
product of a series of energy systems “turning on” and
“turning off,” but rather the smooth blending and
overlap of all three energy systems working
synergistically

14. EXCESS POST-EXERCISE OXYGEN CONSUMPTION
 On termination of exercise, oxygen consumption (VO2)
will gradually return toward baseline levels in an
exponential manner, first demonstrating an initial rapid
component followed by a slow, longer component.

15.  The overall VO2 that is consumed above resting
values during this phase is referred to as the excess
post-exercise oxygen consumption (EPOC).
 EPOC comprises two phases:
 the rapid and
 slow phases.
 The duration of the rapid phase generally lasts
approximately 2 to 3 minutes but may extend out
toward 30 to 60 minutes.
 The slow phase lasts longer, depending on the
magnitude of tissue stimulation (repair and adaptation)
and the amount of recovery needed.

16. CUSTOMIZING ENERGY EXPENDITURE
GOALS
 Rather than design an exercise program that adheres
to an absolute energy expenditure recommendation
(1,000 kcal/week), aim rather for:
1. What is manageable at first, regardless of how many
calories it expends; and
1. Perhaps opt to follow an energy expenditure
prescription that accounts for differences in body
mass (e.g., 14 kcal/kg/week).

17.  Overestimation of the exercise energy expenditure
requirements for an individual will almost certainly
create an unrealistic goal; consequently, this increases
the chances of overtraining, injury, discouragement,
and decreased program adherence.
 Conversely, underestimation of the exercise energy
expenditure requirements might lead to decreased
health and fitness benefits, which can also contribute
to lower program adherence.
 These issues are circumvented by establishing weekly
goals with a relative energy expenditure prescription.