Exercise Physiology Chapter 5 Review

Questions and Answers

Explain direct calorimetry.

Direct calorimetry is the measurement of how much heat is produced, using a calorimeter that has water running through its walls. As heat and energy production increases, the water temperature rises. This method is accurate for resting metabolic measurements but is expensive and slow, with variables that can skew results.

Explain indirect calorimetry.

Indirect calorimetry estimates total body energy expenditure by measuring oxygen intake and carbon dioxide output. It is accurate for steady-state oxidative metabolism and can vary in speed and cost between older and newer methods.

What does the Haldane Transformation allow us to measure?

The Haldane Transformation allows us to measure the volume of inspired air by using the volume of expired air, due to the consistency of nitrogen volumes.

Explain the Respiratory Exchange Ratio (RER). What do those numbers indicate?

The RER represents the ratio of CO2 produced to the amount of O2 utilized. An RER of 0.70 indicates that fat is the primary substrate at rest, while an RER of 1 indicates carbohydrate is the primary fuel source during high-intensity exercise. Signup and view all the answers

At rest, what is the average RER and how many Kcals per liter of oxygen are burned?

The average RER at rest is approximately 0.71, corresponding to about 4.69 Kcals per liter of oxygen burned. Signup and view all the answers

Where does the nonmetabolic CO2 production come from during high levels of exertion?

It comes in response to lactate buildup and bicarbonate that picks up H ions, changing it to carbonic acid which dissociates into CO2 and H2O. Signup and view all the answers

What are the units for Absolute and Relative VO2max, and when is one preferred over the other?

Relative VO2max is measured in ml/kg/min and considers athlete size, while absolute VO2max is measured in L/min and does not account for size. Relative is preferred in exercise science for comparisons among different athletes. Signup and view all the answers

Explain excess post-exercise oxygen consumption (EPOC). How and why does this happen?

EPOC occurs post-exercise when the body's demand for oxygen exceeds the oxygen consumed during early exercise, resulting in an O2 deficit. It replenishes ATP/PCr stores, converts lactate to glycogen, clears CO2, and replenishes hemoglobin and myoglobin. Signup and view all the answers

Explain the lactate threshold and its significance in predicting performance.

The lactate threshold is when blood lactate production rate exceeds lactate clearance rate. A higher lactate threshold indicates better endurance, allowing athletes to perform longer without the buildup of lactate. Signup and view all the answers

What are the characteristics of a successful endurance athlete?

A successful endurance athlete has a high VO2max, a high lactate threshold, high economy of effort, and a high percentage of type 1 muscle fibers. Signup and view all the answers

Define fatigue in your own words.

Fatigue is when an athlete experiences a decline in muscular ability over time, making it difficult to maintain the required intensity. Signup and view all the answers

Study Notes

Direct Calorimetry

Measures heat production to assess energy expenditure.
Utilizes a calorimeter with water-cooled walls to detect temperature changes.
Effective for resting metabolic rates but expensive and slow.
Variables like exercise-induced heat can skew accuracy.

Indirect Calorimetry

Estimates total energy expenditure through oxygen intake and carbon dioxide output.
Accurate only during steady-state oxidative metabolism.
Older methods are slow, while newer devices may be faster but costly.

Haldane Transformation

Allows measurement of inspired air volume using expired air volume.
Relies on the consistency of nitrogen volumes to calculate values.

Respiratory Exchange Ratio (RER)

Represents the ratio of carbon dioxide produced to oxygen consumed.
An RER of approximately 0.70 indicates fat oxidation at rest.
An RER of 1.0 indicates carbohydrate utilization during high-intensity activities.

Kcals per Liter of Oxygen

At rest with an RER of ~0.71, around 4.69 Kcals are burned per liter of oxygen.
Increasing intensity raises Kcals burned per liter, shifting reliance from fat to carbohydrates.

CO2 Production at High Exertion

CO2 production may exceed exhaled CO2 due to nonmetabolic sources.
This additional CO2 comes from bicarbonate reacting to lactate buildup and converting to carbonic acid.

VO2max Measurement

Absolute VO2max is measured in L/min and does not account for body size.
Relative VO2max is measured in ml/kg/min, taking body size into consideration.
Relative VO2max is preferred in exercise science for comparative analysis.

Excess Post-Exercise Oxygen Consumption (EPOC)

Occurs when oxygen demand exceeds intake post-exercise, leading to an oxygen deficit.
EPOC replenishes ATP/PCr stores, clears lactate, and restores hemoglobin and myoglobin levels.

Lactate Threshold

Defined as the point where blood lactate production exceeds lactate clearance.
A higher lactate threshold indicates better endurance performance, allowing longer activity without lactate accumulation.

Characteristics of Successful Endurance Athletes

High VO2max, indicating efficient oxygen utilization.
Elevated lactate threshold for sustained performance.
High economy of effort, demonstrating efficiency in energy expenditure.
Greater proportion of type 1 muscle fibers, suited for endurance activities.

Definition of Fatigue

Characterized by a decline in muscular performance and inability to maintain required intensity over time.

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Description

This quiz covers key concepts from Chapter 5 of Exercise Physiology, specifically focusing on direct calorimetry. Explore the implications and applications of measuring heat production in the context of metabolic studies. Perfect for understanding energy expenditure and calorimetry techniques.