Measuring Energy Expenditure Flashcards
Direct Calorimetry
Using a large sophisticated chamber to directly measure heat produced by the body. It can provide very accurate measures of resting metabolism but it is neither common nor useful
Indirect Calorimetry
Measuring whole-body O2 consumption and CO2 production from expired gases.
What are the measures needed for indirect calorimetry?
volume of air inspired (Vi) or expired (Ve), the fraction of oxygen in the expired air (FeO2) and the fraction of CO2 in the expired air (FeCO2)
How can we calculate the energy expended per liter of oxygen consumed in kilocalories?
By calculating he RER value and comparing the RER value with standard values to determine the metabolic substrates being oxidized
What is the RER value at rest? Of fat? Carbohydrates?
0.78 to 0.80; 0.70; 1.00
isotopes can be used to determine…
Metabolic rate over long periods of time.. they are injected into the body and the rate they are cleared can be used to calculate CO2 production and then caloric expenditure.
What is metabolic rate?
the rate at which the body used energy
What is Basal Metabolic Rate?
the minimum amount of energy required by the body to sustain basic cellular functions an is highly related to fat free body mass and body surface area.
Metabolism increases with _____ but _____ is limited
increased exercise intensity; oxygen is limited (VO2max)
what is the EPOC
Excess Postexercise Oxygen Consumption : elevated metabolic heart rate above resting levels that occurs during the recovery period immediately after exercise has ceased
what is the lactate threshold?
the point at which blood lactage production begins to exceed the body’s ability to clear or remove lactate, resulting in rapid increase in blood lactate concentration during exercise of increased intensity.
What are the major causes of fatigue
1) inadequate energy delivery/metabolism
2) accumulation of metabolic by-products
3) failure of muscle contractile mechanism
4) altered neural control of muscle contraction
