Exercise Phys Exam 2 (with lecture notes)

What components make up Total Energy Expenditure (TEE)?

TEE includes basal metabolic rate (BMR), activity energy expenditure (AEE), and energy used for digestion.

Which component of Total Energy Expenditure (TEE) is the most variable among individuals?

Activity energy expenditure (AEE) is the most variable due to differences in movement and daily activities.

How does fat-free mass influence basal metabolic rate (BMR)?

Fat-free mass is the primary determinant of BMR because metabolically active tissues require more energy.

What is metabolic scope?

Metabolic scope is TEE/BMR, reflecting how much energy a person uses beyond their resting metabolic rate.

What are the principles behind measuring energy expenditure?

Measuring energy expenditure is based on oxygen consumption and CO₂ production linked to energy production.

How does direct calorimetry measure energy expenditure?

It measures heat production in a sealed chamber to assess energy expenditure.

What are the pros and cons of using direct calorimetry?

Pros: Accurate over time; useful for resting metabolism. Cons: Expensive; not practical for exercise; influenced by heat from equipment.

What is indirect calorimetry and its limitations?

Indirect calorimetry estimates energy expenditure by measuring oxygen consumption and CO₂ production, but is only valid during steady-state exercise.

What is doubly labeled water used for?

Doubly labeled water is ingested to measure total energy expenditure (TEE) by tracking isotopes in urine.

How does the respiratory exchange ratio (RER) indicate fuel utilization?

RER = V˙CO2/V˙O2; RER = 1.0 indicates carbohydrate metabolism, while RER = 0.70 indicates fat metabolism.

Why does RER increase with exercise intensity?

RER increases because the body relies more on carbohydrates, which provide ATP faster than fat oxidation.

How does metabolic rate change with exercise intensity?

Metabolic rate increases proportionally with exercise intensity.

What is the Modified Weir Equation used for?

It estimates kcal/min using both V˙O2 and V˙CO2 for better accuracy in energy expenditure due to different fuel outputs.

What is the slow component of V˙O2 uptake?

It refers to a gradual increase in oxygen uptake over time at high exercise intensities due to reliance on Type II fibers.

What factors contribute to a higher V˙O2 max?

High oxygen uptake, cardiac output, mitochondrial density, and enhanced oxygen delivery are key factors.

What is excess post-exercise oxygen consumption (EPOC)?

EPOC is the elevated oxygen consumption after exercise to restore ATP, remove CO₂, repair muscles, and replenish glycogen.

How does economy of effort impact endurance performance?

More efficient athletes use less energy at the same pace, enhancing their endurance performance.

What is metabolic compensation in physical activity?

Increased activity energy expenditure leads to reduced energy spent in other areas, limiting weight loss.

What is the Central Governor Model of fatigue?

It posits that the brain regulates physical exertion to prevent damage rather than fatigue being purely energy depletion.

What are the two definitions of fatigue?

Muscle fatigue model: inability to sustain power output; Perceived exertion model: sensation of tiredness.

What is the difference between peripheral and central fatigue?

Peripheral fatigue occurs in muscles due to energy depletion or byproducts, while central fatigue occurs in the brain and nervous system.

How does glycogen depletion contribute to fatigue?

Glycogen depletion forces reliance on fats, which are less efficient for ATP production.

What effect does increased hydrogen ion (H+) concentration have on muscle function?

It lowers pH, inhibiting glycolytic enzymes and reducing ATP production.

How does bicarbonate act as a buffer?

Bicarbonate binds with H+ ions to maintain pH balance and prevent excessive acidity.

What are central and peripheral fatigue causes?

Central fatigue causes are neural control issues and psychological factors; peripheral fatigue causes relate to energy delivery and metabolic byproducts.

Why does lactic acid accumulate during intense exercise?

When oxygen is limited, lactate cannot be oxidized quickly, leading to the accumulation of lactate and hydrogen ions.

What is the impact of elevated acidity on muscle performance?

High acidity from H+ accumulation can impair muscle contraction and glycolysis, leading to fatigue.

What is the role of reactive oxygen species (ROS) in fatigue?

ROS are metabolic byproducts that can accumulate in muscles, causing oxidative stress and limiting contraction.

What are common side effects of sodium bicarbonate supplementation?

GI distress, including thirst, bloating, nausea, diarrhea, and vomiting.

What does the economy in sports refer to?

Using less energy for a given pace or amount of work, improving performance in endurance activities.

How does velocity and oxygen cost relate in endurance running?

More economical runners use less oxygen per kilogram of body mass, enhancing performance.

What is EPOC and its significance?

EPOC, or excess post-exercise oxygen consumption, indicates elevated metabolic rate post-exercise for recovery and repaying oxygen debt.

What is constrained energy expenditure?

The concept that increased activity leads to subconscious reductions in energy expenditure elsewhere to conserve energy.