Exercise Physiology Exam 1!

The activity of creatine kinase is increased by a rise in _blank levels in the muscle fiber.

ADP

Which of the following statements about glycolysis is correct?

Glycolysis involves the breakdown of glucose into two molecules of pyruvate or lactate

The actual net ATP yield from aerobic metabolism of one molecule of glucose is different from the theoretical yield because

it accounts for the fact that the energy provided by NADH and FADH is required not only for ATP production but also to transport ATP across the mitochondrial membrane.

Both the first and second proton pumps in the electron transport chain transport blank protons ( H+ ) across mitochondrial inner membrane whereas the third proton pump moves blank protons ( H+ ) across mitochondrial inner membrane.

4, 2

The enzyme that catalyzes the formation of lactate from pyruvate is

lactate dehydrogenase

Stored polysaccharides (i.e., carbohydrates) in muscle and other tissues in animals are called

glycogen

The caloric (kcal) yield of one gram of protein is approximately

4 kcal/g

A class of enzymes called kinases are responsible for

adding phosphate groups to a molecule (i.e., phosphorylation of substrates).

When a muscle transitions from rest (no contractile activity) to exercise (increased contractile activity), ATP breakdown increases. This breakdown of ATP results in a rise in cytosolic levels of both blank and blank; this activates the rate-limited enzyme in both the Krebs (citric acid) cycle to increase ATP production.

Calcium and ADP

If muscle glycogen is the initial substrate, the net production of ATP resulting during glycolysis is.

3 molecules

In the hydrolytic model of oxidative phosphorylation, the four water tanks represent

the four energy pools in muscle.

Each pair of electrons passed through the electron transport chain from NADH to oxygen releases enough energy to produce

2.5 ATP

The primary purpose of the Krebs cycle is to

complete the oxidation of foodstuffs using NAD and FAD as hydrogen (electron) carriers

The conversion of pyruvate to lactate requires

Both the enzyme lactate dehydrogenase and NADH + H+ are correct.

Coupled reactions are defined as

reactions that are linked together, with the liberation of free energy in one reaction being used to drive the second reaction.

Enzymes are catalysts that increase the rate of reactions by

lowering the energy of activation.

Aerobic production of ATP occurs in the

in the mitochondria in a process called oxidative phosphorylation

A high level of _blank in the muscle fiber would slow glycolysis by inhibiting its rate-limiting enzyme.

ATP

The rate-limiting enzyme in the electron transport chain is

cytochrome oxidase

The primary function of the Krebs cycle is to

complete the oxidation of carbohydrates, fats, and proteins (i.e., form NADH and FADH).

Elevated blood levels of lactate dehydrogenase can assist in the diagnosis of which medical condition?

myocardial infarction

Skeletal muscle fibers store carbohydrate in the form of glycogen rather than individual glucose molecules because

storage of individual glucose molecules increases osmotic pressure between inside and otuside of cell

Three molecules of NADH are produced during one turn of the citric acid cycle. How many total ATP molecules can be produced from these three NADH molecules?

7.5 ATP

In the hydrolytic model of oxidative phosphorylation, mitochondria combust fuels to release energy and form ATP; this occurs in a three-step process. Step one of this process involves

harvest of electrons from fuels.

The total ATP tally from the aerobic breakdown of glucose is

32 ATP

The rate-limiting enzyme in glycolysis is

phosphofructokinase

In general, the higher the intensity of exercise, the greater the contribution of

anaerobic energy production

Triglycerides are comprised of

FFA and glycerol

The fats stored in muscle and adipose tissue that play an important role as an energy substrate are

triglycerides

Compared to NADH, FADH produces less ATP because

the electrons from FADH enter the electron transport chain at a later stage than those by NADH.

The metabolic process of converting foodstuffs into a biological usable form of energy is called

bioenergetics

The term "lactate" refers to

a potential end-product of glycolysis.

the conjugate base of lactic acid.

the salt of lactic acid.

The process of beta-oxidation involves

a series of reactions converting fatty acids into acetyl-CoA.

The two most important electron carriers in bioenergetic chemical reactions are

NAD and FAD

The calculated efficiency for aerobic respiration is approximately

34%

The immediate source of energy for muscular contraction is

ATP

The rate-limiting enzyme in the Krebs cycle is

isocitrate dehydrogenase

Body temperature increases during exercise. A 2°C increase in muscle temperature during exercise would likely

increase enzyme activity

Rate-limiting enzymes are often located

near the beginning of a metabolic pathway.

By definition, an endergonic reaction is

a chemical reaction that requires energy to be added to the reactants before the reaction will take place

Which of the following statements is true concerning the electron transport chain?

The primary purpose of the electron transport chain is to harvest the energy from electrons moving down this pathway to produce ATP and water.

The simplest and most rapid pathway for producing ATP during exercise is through

ATP-CP system

What are the three pathways that produce ATP for energy in the body?

ATP-PC, glycolysis, oxidative phosphorylation.

Which pathway is the fastest for ATP production?

ATP-PC pathway.

Which pathway is slower but more efficient for ATP production?

Oxidative phosphorylation.

Which pathway requires oxygen?

Oxidative phosphorylation.

What are the byproducts of ATP production during exercise?

Carbon dioxide (CO₂).

How is exercise intensity measured?

By oxygen consumption relative to resting value or relative to the subject's maximum capacity (% VO2 max).

What is steady-state VO₂ and how long does it typically take to reach it during exercise?

Steady-state VO₂ is the level of oxygen consumption maintained during exercise, typically reached within 1 to 4 minutes.

What factors contribute to excess post-exercise oxygen consumption (EPOC)?

Oxygen debt, lactate conversion to glucose, restoration of muscle and blood oxygen stores, elevated hormones, and elevated body temperature.

What does a plateau in O2 consumption during a graded exercise test indicate?

It is the gold standard for verifying VO2max.

What are the secondary criteria for achieving VO2max?

Reaching age-predicted maximal heart rate, achieving blood lactate concentration of 8 mM or higher, and attaining a respiratory exchange ratio of 1.15 or higher.

Oxidative phosphorylation

A metabolic pathway that uses oxygen to convert energy stored in nutrients into ATP, involving the electron transport chain and Krebs cycle.

ATP-PC pathway

The fastest energy-producing pathway that provides immediate ATP through phosphocreatine for short bursts of high-intensity activity.

Glycolysis

A metabolic pathway that breaks down glucose to produce ATP, usable in both aerobic and anaerobic conditions.

Byproducts of glycolysis

The byproducts include pyruvate, which can proceed to aerobic pathways or convert to lactate in anaerobic conditions.

Excess Postexercise Oxygen Consumption (EPOC)

The amount of oxygen consumed after exercise, required to restore the body to its resting state, including replenishing energy stores and clearing lactate.

Steady-state VO₂

The level of oxygen consumption where the body can meet ATP demands during prolonged exercise, typically reached within 1 to 4 minutes.

VO₂ max

The maximum rate of oxygen consumption measured during incremental exercise, indicating cardiorespiratory fitness.

Verification Test for VO₂max

A method performed to confirm VO₂max where a subject exercises at higher workloads to verify oxygen consumption matches or exceeds the previously recorded max.

Aerobic pathways

Energy production systems that require oxygen and are more efficient for sustaining ATP production over prolonged periods.

Intensity Domains

Categories of exercise intensity based on oxygen consumption, ranging from moderate to severe levels and expressed as a percentage of VO₂ max.

What is the body's preferred fuel source at rest and during intense exercise?

At rest, the body prefers fat; during intense exercise, it prefers carbohydrates.

What does R represent in exercise metabolism, and what do its values indicate?

R represents the respiratory exchange ratio; R = 0.70 indicates 100% fat utilization, R = 0.85 indicates 50% fat and 50% carbohydrate, and R = 1.00 indicates 100% carbohydrate.

What factors influence fuel selection during exercise?

Factors include intensity and duration of exercise, availability of fuels, and diet.

What happens to carbohydrate metabolism during prolonged, low to moderate-intensity exercise?

There is a decrease in carbohydrate metabolism and an increase in fat metabolism due to increased lipolysis.

How does the body use proteins during exercise?

Proteins are broken down into amino acids, with some converted to glucose; they contribute less than 2% of fuel for exercise under 1 hour and up to 5-10% for longer exercises.

What is the crossover point in exercise metabolism?

The crossover point is where the utilization of carbohydrates increases as exercise intensity increases and fat utilization decreases.

What is lipolysis and what role does it play in energy metabolism?

Lipolysis is the breakdown of triglycerides into glycerol and free fatty acids, stimulated by hormones, and plays a key role in fat metabolism during exercise.

How do carbohydrate sources differ during low-intensity and high-intensity exercise?

Low-intensity exercise primarily uses blood glucose, while high-intensity exercise primarily uses muscle glycogen as the fuel source.

What is the impact of endurance training on fuel utilization?

Endurance training enhances the body's ability to utilize fat as fuel and maintain energy during prolonged exercise.

What is the importance of glycogen in physical performance?

Glycogen provides readily available energy for muscle contraction during exercise, particularly in high-intensity activities.

Respiratory Exchange Ratio (R)

The ratio of carbon dioxide produced to oxygen consumed during exercise, indicating the fuel source utilized.

Crossover Point

The exercise intensity at which the body shifts from predominantly using fat to carbohydrate as its energy source.

Lipolysis

The breakdown of lipids into glycerol and free fatty acids, occurring during low to moderate-intensity exercise.

Glycogenolysis

The process of breaking down glycogen into glucose for energy, particularly during high-intensity exercise.

Muscle Glycogen

The primary carbohydrate source for high-intensity exercise, stored within muscle cells.

Blood Glucose (BG)

The amount of glucose present in the blood, serving as a fuel source during low-intensity exercise.

Endurance Training

A type of physical training that improves the body's ability to utilize fat as a fuel source during prolonged exercise.

Beta-Oxidation

The metabolic process of breaking down fatty acids for energy, which requires more steps compared to carbohydrate metabolism.

Triglycerides

A type of fat found in the body, serving as a noteworthy energy source, especially during moderate-intensity exercise.

Amino Acids

Building blocks of proteins, which can be converted to glucose or other intermediates for energy during prolonged exercise.

Substrate Shift

The change in the predominant fuel source utilized by the body as exercise intensity or duration changes.

Insulin

A hormone that regulates blood glucose levels, inhibiting lipolysis when present in high amounts.

Caloric Value of Carbohydrates

Each gram of carbohydrate yields approximately 4 kilocalories of energy.

Caloric Value of Fats

Each gram of fat yields approximately 9 kilocalories of energy.

Fat Oxidation

The process of utilizing fat as a fuel source during exercise, becoming more dominant at lower intensities.

Intensity and Duration

Two critical factors that influence the selection of fuel sources during exercise.

What is the significance of Ethan Strand's indoor mile record set on February 1, 2025?

It is the third fastest indoor mile of all time.

What is VO2max?

The maximum rate of oxygen consumption measured during intense exercise.

What are the primary factors influencing VO2max?

Oxygen transport/delivery and oxygen utilization.

What indicates the lactate threshold (LT) for untrained subjects?

LT occurs at approximately 50-60% VO2max.

What is the Onset of Blood Lactate Accumulation (OBLA)?

It refers to the point at which lactate exceeds a pre-determined concentration, typically around 4.0 mM/L.

What are some contributors to the rise in lactate during exercise?

Increased lactate production, low muscle oxygen, hormones like epinephrine, and decreased lactate removal.

What happens to glycolysis at 50-65% VO2max regarding lactate production?

Rapid glycolysis occurs, leading to increased lactate due to the high levels of NADH + H+.

What does an R value of 0.70 represent in carbohydrate vs fat utilization?

100% fat utilization.

What is the function of lactate during exercise?

Lactate acts as a metabolic fuel and helps in energy production when oxygen levels are low.

Why is lactic acid not considered the main contributor to muscle soreness?

Lactic acid is rapidly cleared from the muscles after exercise and is not responsible for delayed onset muscle soreness.