Chapter Three

Question 1

​​Energy stored in the chemical bonds of ___ is used to power muscular activity. The replenishment of ATP in human skeletal muscle is accomplished by three basic energy systems: ___, ____ and _____.

Answer 1

​​Energy stored in the chemical bonds of ATP is used to power muscular activity. The replenishment of ATP in human skeletal muscle is accomplished by three basic energy systems: phosphagen, glycolytic, and oxidative.

Question 2

The ______ system provides energy for short, high-intensity activities by using stored ATP and creatine phosphate.

Answer 2

Phosphagen

Question 3

______ is the body’s immediate source of energy, used for all muscle contractions.

Answer 3

ATP

Question 4

______ ______ is a high-energy compound stored in muscles and used to quickly regenerate ATP.

Answer 4

Creatine phosphate

Question 5

The enzyme ______ ______ breaks down ATP during muscle contraction.

Answer 5

Myosin ATPase

Question 6

______ is the breakdown of carbohydrates to resynthesize ATP, either anaerobically or aerobically.

Answer 6

Glycolysis

Question 7

Stored form of carbohydrates in muscle and liver is called ______.

Answer 7

Glycogen

Question 8

. During fast glycolysis, ______ is produced and can accumulate in the muscles.

Answer 8

lactate

Question 9

Accumulation of hydrogen ions (______) during intense exercise lowers muscle ______, causing fatigue.

Answer 9

H+, pH

Question 10

The process of making glucose from non-carbohydrate sources is called ______.

Answer 10

Gluconeogenesis

Question 11

The ______ ______ recycles lactate from the muscle to the liver, where it’s turned back into glucose.

Answer 11

cori cycle

Question 12

The point at which lactate begins to accumulate in the blood is known as the ______ ______.

Answer 12

Lactate threshold (LT)

Question 13

The point where blood lactate reaches 4 mmol/L is called ______.


Answer 13

Onset of blood lactate accumulation (OBLA)

Question 14

The ______ system is the primary energy source during rest and low-intensity activity.

Answer 14

Oxidative

Question 15

In aerobic glycolysis, glucose is broken down into ______, which enters the mitochondria for further energy production.

Answer 15

Pyruvate

Question 16

The ______ ______ is a series of reactions in the mitochondria that fully oxidize pyruvate

Answer 16

Krebs cycle

Question 17

The ______ ______ ______ transfers electrons to produce ATP in the mitochondria.

Answer 17

Electron transport chain (ETC)

Question 18

______ are proteins in the ETC that carry electrons and help produce ATP.

Answer 18

Cytochromes

Question 19

______ ______ is the process of forming ATP through the electron transport chain.

Answer 19

Oxidative phosphorylation

Question 20

______ breaks down fat in adipose tissue so it can be used for energy.

Answer 20

Hormone-sensitive lipase

Question 21

______ ______ is the breakdown of fatty acids to form acetyl-CoA, which enters the Krebs cycle.

Answer 21

Beta oxidation

Question 22

______ is a compound that helps quickly regenerate ATP in the phosphagen system.

Answer 22

creatine

Question 23

The process of breaking down glycogen into glucose is called ______.


Answer 23

Glycogenolysis

Question 24

The ______ ______ describes how the body switches from using fat to carbohydrates as exercise intensity increases.

Answer 24

Crossover concept

Question 25

______ ______ is the amount of oxygen the body uses during activity.

Answer 25

Oxygen uptake

Question 26

______ ______ occurs when the body uses energy before oxygen supply meets demand.

Answer 26

Oxygen deficit

Question 27

______ ______ is the extra oxygen consumed after exercise to return the body to homeostasis.

Answer 27

Oxygen debt

Question 28

______ is the elevated oxygen intake after exercise, used to restore the body (also called oxygen debt).

Answer 28

Excess postexercise oxygen consumption (EPOC)

Question 29

______ is the maximum weight a person can lift for one repetition.

Answer 29

1RM

Question 30

All three energy systems are active at a given time; however, the extent to which each is used depends primarily on the intensity of the activity and secondarily on its duration.

Answer 30

All three energy systems are active at a given time; however, the extent to which each is used depends primarily on the intensity of the activity and secondarily on its duration.

Question 31

-The _____ energy system primarily supplies ATP for high-intensity activities of short duration, -The ____ system for moderate- to high-intensity activities of short to medium duration, -The ____ system for low-intensity activities of long duration.

Answer 31

he phosphagen energy system primarily supplies ATP for high-intensity activities of short duration, the glycolytic system for moderate- to high-intensity activities of short to medium duration, and the oxida­tive system for low-intensity activities of long duration.

Question 32

The substrate molecule ____ is broken down by hormone-sensitive lipase to produce free fatty acids for beta oxidation in the oxidative energy system.

Answer 32

Triglycerides

Question 33

____ is a vital energy source, particularly for high-intensity exercise. ____ storage within the body is limited to about 500 g (about 2,000 kcal), and glycogen depletion is associated with fatigue. ____ repletion can occur rapidly but may take up to 24 hours for complete resynthesis.

Answer 33

Glycogen

Question 34

All three energy systems have the capacity to adapt based on the _________

Answer 34

All three energy systems have the capacity to adapt based on the principle of train­ing specificity.

Question 35

_____ is the fundamental mechanical ele­ment that can produce, change, or stop the motion of a body.

Answer 35

force

Question 36

Human movement is produced and con­ trolled by the sum of all internal (muscle) and external (gravity, loading) forces acting on limb segments.

Answer 36

Human movement is produced and con­ trolled by the sum of all internal (muscle) and external (gravity, loading) forces acting on limb segments.

Question 37

The ______ ______ describes how the body switches from using fat to carbohydrates as exercise intensity increases.

Answer 37

Crossover concept

Question 38

______ is the elevated oxygen intake after exercise, used to restore the body (also called oxygen debt).

Answer 38

Excess postexercise oxygen consumption (EPOC)

Question 39

The phosphagen system is the primary source of ATP for ____-term, high-intensity activities like jumping and sprinting.

Answer 39

short

Question 40

The phosphagen system relies on the chemical reactions of ATP and ____ phosphate, both phosphagens.

Answer 40

creatine

Question 41

The enzyme ____ ATPase increases the rate of ATP breakdown into ADP and inorganic phosphate, releasing energy.

Answer 41

myosin

Question 42

Creatine kinase increases the rate of ATP synthesis by combining ____ with a phosphate group to form ATP.

Answer 42

ADP

Question 43

Type ____ (fast-twitch) muscle fibers contain greater concentrations of phosphagens than type I fibers.

Answer 43

II

Question 44

An increase in ____ concentration in muscle cells promotes creatine kinase activity, while high ATP inhibits it.

Answer 44

ADP

Question 45

Glycolysis is the breakdown of ____ (stored in muscle) or glucose (from blood) to produce ATP.

Answer 45

glycogen

Question 46

Glycolysis is the primary ATP source for high-intensity activities lasting up to about ____ minutes.

Answer 46

2

Question 47

The end product of slow (aerobic) glycolysis is ____, which enters the mitochondria for further energy production.

Answer 47

pyruvate

Question 48

I n fast (anaerobic) glycolysis, pyruvate is converted to ____ via the enzyme lactate dehydrogeInase.

Answer 48

lactate

Question 49

The rate-limiting enzyme of glycolysis, ____, controls the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.

Answer 49

Phosphofructokinase (PFK)

Question 50

Glycolysis produces a net of ____ ATP molecules from one glucose molecule, or ____ ATP if glycogen is used.

Answer 50

2,3

Question 51

Muscle fatigue during intense exercise is primarily due to the accumulation of ____ ions, not lactate.

Answer 51

H+

Question 52

Lactate can be converted to glucose in the liver through a process called the ____ cycle.

Answer 52

cori

Question 53

The ____ threshold is the point at which blood lactate begins to accumulate significantly during exercise.

Answer 53

lactate

Question 54

The onset of blood lactate accumulation (OBLA) occurs when blood lactate reaches approximately ____ mmol/L.

Answer 54

4

Question 55

The oxidative system is the primary ATP source at ____ and during low-intensity, long-duration activities.

Answer 55

rest

Question 56

In the presence of oxygen, glycolysis produces pyruvate, which is converted to ____ in the mitochondria.

Answer 56

Acetyl-CoA

Question 57

The Krebs cycle produces ____ ATP (via GTP), 6 NADH, and 2 FADH2 per glucose molecule.

Answer 57

2

Question 58

In the electron transport chain, each NADH yields approximately ____ ATP, while each FADH2 yields ____ ATP.

Answer 58

3,2

Question 59

Fats undergo ____ oxidation in mitochondria to produce acetyl-CoA, NADH, and FADH2.

Answer 59

beta

Question 60

Proteins contribute ____% to ____% of energy during prolonged exercise, primarily via amino acid breakdown.

Answer 60

3,18

Question 61

Creatine phosphate can deplete by ____% to ____% during 5–30 seconds of high-intensity exercise.

Answer 61

50, 70

Question 62

Full glycogen repletion post-exercise takes approximately ____ hours with adequate carbohydrate intake.

Answer 62

24

Question 63

Optimal glycogen repletion requires ____ g of carbohydrate per kg of body weight every 2 hours post-exercise.

Answer 63

1.2

Question 64

The ____ deficit is the initial energy gap at the start of exercise, covered by anaerobic systems.

Answer 64

oxygen

Question 65

Excess postexercise oxygen consumption (____) is the elevated oxygen use after exercise to restore the body.

Answer 65

EPOC

Question 66

Glycogen becomes the preferred fuel source at intensities above about ______ of maximal oxygen uptake.


Answer 66

At exercise intensities above ~60%-75% VO₂max, carbohydrates (glycogen) become the primary fuel.

Question 67

Slow ATP-producing systems like the _____ system can utilize carbs (glycogen), fats (fatty acids), and proteins (in extreme cases).

Answer 67

Slow ATP-producing systems like the oxidative system can utilize carbs (glycogen), fats (fatty acids), and proteins (in extreme cases).

Question 68

Creatine phosphate is part of the fast ____ system

Answer 68

phosphagen

Question 69

At rest, approximately ____% of ATP is derived from fats and ____% from carbohydrates in the oxidative system.

Answer 69

70, 30

Question 70

Fat oxidation, dominant at low intensities, relies on the enzyme ____ to break down triglycerides into free fatty acids.

Answer 70

: Hormone-sensitive lipase

Question 71

To optimize glycogen repletion after high-intensity exercise, ____ g of carbohydrate per kg of body weight should be consumed every 2 hours.

Answer 71

1.2

Question 72

Fatigue during high-intensity exercise is often due to the depletion of ____, a key carbohydrate substrate.

Answer 72

glycogen

Question 73

The ____ threshold often aligns with the crossover point, marking increased reliance on anaerobic glycolysis and lactate production.

Answer 73

lactate

Question 74

In prolonged steady-state exercise (>90 minutes), the body shifts back to using primarily ____ and some ____ as fuel sources.

Answer 74

Fats, Proteins

Question 75

The enzyme ____ regulates glycolysis and contributes to the rapid ATP production from carbohydrates during the crossover.

Answer 75

Phosphofructokinase (PFK)

Question 76

High-intensity exercise above maximal oxygen uptake relies heavily on ____ systems, reducing exercise duration.

Answer 76

Anaerobic

Question 77

Short, high-intensity activities like sprinting primarily rely on the ____ system.

Answer 77

Phosphagen

Question 78

Long-distance running or cycling primarily stresses the ____ system for ATP production.

Answer 78

Oxidative

Question 79

Training with short rest periods (30–60 seconds) targets the ____ system to improve lactate threshold.

Answer 79

Glycolytic

Question 80

Creatine supplementation can enhance the repletion of the ____ system for high-intensity performance.

Answer 80

Phosphagen

Question 81

The crossover concept describes the shift from using primarily ____ to ____ as the dominant energy substrate as exercise intensity increases.

Answer 81

Fats, Carbohydrates

Question 82

The crossover to carbohydrate reliance typically occurs at ____% to ____% of maximal oxygen uptake (VO₂ max).

Answer 82

60, 75

Question 83

During high-intensity aerobic exercise, nearly ____% of energy comes from carbohydrates, assuming sufficient glycogen stores.

Answer 83

100%