Chapter 3: Bioenergetics of Exercise and Training Flashcards
1
Q
Bioenergetics
A
- The flow of energy in a biological system
- Primarily concerned with converting macros into usable forms of energy (ATP)
2
Q
Energy
A
The capacity to do work
3
Q
Catabolism
A
- The breakdown of large molecules into smaller molecules
- Associated with the release of energy
4
Q
Anabolism
A
- The synthesis of larger molecules from smaller molecules
- Can be accomplished using the energy released from catabolism
5
Q
Exergonic Reactions
A
Energy-releasing reactions that are generally catabolic
6
Q
Endergonic Reactions
A
Require energy and include anabolic processes
7
Q
Metabolism
A
The total of all catabolic/exergonic and anabolic/endergonic reactions in a biological system
8
Q
Adenosine Triphosphate (ATP)
A
- Composed of adenosine and three phosphates
- Potential energy in bond drives all biological work
9
Q
Hydrolysis
A
- The breakdown of one molecules of ATP to yield energy
- Requires one molecule of water
10
Q
ATPase
A
Enzyme that catalyzes the hydrolysis of ATP
11
Q
Myosin ATPase
A
The enzyme that catalyses ATP hydrolysis for crossbridge cycling
12
Q
Calcium ATPase
A
Hydrolyzes ATP when pumping calcium into the sarcoplasmic reticulum
13
Q
Sodium-Potassium ATPase
A
Hydrolyzes ATP to maintain the sarcolemmal concentration gradient after depolarization
14
Q
ATP Hydrolysis
A
ATP + H2O –> ADP + Pi + H+ + Energy
15
Q
ADP
A
- Adenosine diphosphate
- Result of ATP hydrolysis
16
Q
Pi
A
Inorganic Phosphate
17
Q
AMP
A
- Adenosine Monophosphate
- Result of ADP hydrolysis
18
Q
3 Basic Energy Systems
A
- Phosphagen System
- Glycolysis
- Oxidative System
19
Q
Anaerobic Processes
A
- Does not require the presence of oxygen
- Phosphagen system
- Glycolytic systems
- Occur in the sarcoplasm of the muscle cell
20
Q
Aerobic Processes
A
- Requires the presence of oxygen
- Krebs cycle
- Oxidative system
- Occur in the mitochondria of the muscle cell
21
Q
Which macronutrient can be metabolized anaerobically?
A
Carbs
22
Q
Phosphagen System
A
- Drives short-term, high-intensity activities
- Highly active at the start of activity, regardless of intensity
- Relies on hydrolysis of ATP and breakdown of creatine phosphate/phosphocreatine
23
Q
Creatine Kinase
A
- Enzyme that catalyzes synthesis of ATP from CP/PCr and ADP
- ADP + CP ATP + Creatine
24
Q
How much ATP does the body store at any given time?
A
80-100 g (not much)
25
Can ATP be completely depleted?
No, too important to cellular function
26
Adenylate Kinase Reaction
- AKA myokinase reaction
- 2 ADP ATP + AMP
- Used to rapidly replenish ATP
27
Relationship between adenylate kinase reaction and glycolysis
This reaction acts as a stimulant for glycolysis
28
What acts as a control for the reactions of the phosphagen system?
Law of mass action (mass action effect)
29
Law of Mass Action (Mass Action Effect)
- Concentration of reactants or products (or both) in solution will drive the direction of the reactions
- If there's an enzyme involved, enzyme concentration is also a major regulatory factor
30
Glycolysis
- Breakdown of glucose (carbs)
| - Occurs in the cytosol of the cell
31
What is the end result of glycolysis?
Pyruvate
32
Pyruvate may proceed in which directions?
1. Can be converted to lactate in the sarcoplasm (fast/anaerobic)
2. Can be shuttled into the mitochondria (slow/aerobic)
33
Why is glycolysis limited in duration when pyruvate is converted into lactate?
H+ production and the subsequent decrease in pH
34
How is the direction for pyruvate determined?
The energy demands of the cell
35
What enzyme catalyzes the formation of lactate from pyruvate?
Lactate dehydrogenase
36
Does lactic acid form as the result of anaerobic glycolysis?
NO
37
Does lactate cause fatigue?
NO
38
What causes fatigue?
- Proton (H+) accumulation
| - H+ interferes with muscle's excitation/contraction coupling (possibly inhibiting the binding of calcium)
39
Metabolic Acidosis
- Exercise-induced decrease in pH
| - May be partially responsible for peripheral fatigue occurring during exercise
40
Cori Cycle
Process by which lactate is delivered to the liver, where it is converted into glucose
41
Net Reaction of Glycolysis --> Lactate
Glucose + 2Pi + 2ADP --> 2 Lactate + 2ATP + H2O
42
Net Reaction of Glycolysis --> Pyruvate
Glucose + 2 Pi + 2 ADP + 2 NAD+ --> 2 Pyruvate + 2 ATP + 2 NADH + 2 H2O
43
2 Primary Mechanisms for ATP Resynthesis
- Substrate-level phosphorylation
| - Oxidative phosphorylation
44
Substrate-level Phosphorylation
Refers to the direct resynthesis of ATP during a single reaction
45
Oxidative Phosphorylation
Refers to the resynthesis of ATP in the electron transport chain
46
Phosphofructokinase (PFK)
- The enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-biphosphate
- Rate-limiting step
47
Glycogenolysis
The process of breaking down muscle glycogen
48
Glycogen Phosphorylase
The enzyme that catalyzes the breaking down of muscle glycogen
49
What factors stimulate glycolysis?
- High concentration of ADP, Pi, and ammonia
| - Slight decrease in pH and AMP
50
What factors inhibit glycolysis?
Markedly lower pH, ATP, CP, citrate, and free fatty acids
51
3 enzymes which are critical for regulating glycolysis
- Hexokinase
- PFK
- Pyrivate kinase
52
Allosteric Regulation
Occurs when the end product of a reaction or series of reactions feeds back to regulate the turnover rate of key enzymes in the metabolic pathways
53
Allosteric Inhibition
When an end product binds to the regulatory enzyme and decreases its turnover rate and slows product formation
54
Allosteric Activation
When an activator binds with the enzyme and increases its turnover rate
55
Hexokinase
- Catalyzes the phosphorylation of glucose to glucose-6-phosphate
- Allosterically inhibited by concentration of glucose-6-phosphate in the sarcoplasm
56
Lactate Threshold
- An abrupt increase above the baseline concentration of blood lactate
- Represents a significant dependence on anaerobic mechanics for energy production
- Corresponds well with the ventilatory threshold
- Often used as a marker of the anaerobic threshold
57
When does LT occur in untrained individuals?
At ~50-60% of VO2max
58
When does LT occur in aerobically trained individuals?
At ~70-80% of VO2max
59
Onset of Blood Lactate Accumulation (OBLA)
- An increase in the rate of lactate accumulation at higher relative exercise intensities
- 4 mmol/L
60
What substrates does the aerobic system use for energy?
Carbs and fats (not proteins)
61
Beta Oxidation
- A series of reactions in which free fatty acids are broken down
- Results in the formation of acetyl-CoA and H+
- Acetyl-CoA enters Krebs cycle and H+ is carried by NADH and FADH2 to the ETC
62
Contribution of protein to metabolism
- Negligible during short exercise
| - 3-18% of energy demands during prolonged activity
63
Branched-chain Amino Acids
- The major amino acids that are oxidized in skeletal muscle
- Leucine, isoleucine, and valine
- Alanine, aspartate, and glutamate may also be used
64
Rate-limiting step for Kreb cycle
Conversion of isocitrate to alpha-ketoglutarate (catalyzed by isocitrate dehydrogenase)
65
Energy System for Activities 0-6 seconds
Intensity of Event: Extremely high
| Primary Energy System Used: Phosphagen
66
Energy System for Activities 6-30 seconds
Intensity of Event: Very high
| Primary Energy System Used: Phosphagen and fast glycolysis
67
Energy System for Activities 30 s to 2 min
Intensity of Event: High
| Primary Energy System Used: Fast glycolysis
68
Energy System for Activities 2-3 min
Intensity of Event: Moderate
| Primary Energy System Used: Fast glycolysis and oxidative system
69
Energy System for Activities >3 min
Intensity of Event: Low
| Primary Energy System Used: Oxidative system
70
Glycogen stores in the body
- 300-400 g in muscle
| - 70-100 g in the liver
71
Bioenergetic Limiting Factors
- ATP and CP
- Muscle glycogen
- Liver glycogen
- Fat stores
- Lower pH
72
ATP and CP are limiting factors for activities such as?
High intensity, short duration exercises like the 100 m run or Olympic weightlifting
73
Muscle glycogen is a limiting factor for activities such as?
- Marathon or triathalon
| - Weightlifting
74
Liver glycogen is a limiting factor for activities such as?
Low intensity, long duration exercises like a marathon or triathalon
75
Fat stores is a limiting factor for activities such as?
Not much, the activity it has the most impact on is a marathon
76
Lower pH is a limiting factor for activities such as?
Longer duration, high intensity activities like a 400 m run or Olympic weightlifting
77
Oxygen Deficit
- The aerobic system responds slowly to exercise, so anaerobic systems fuel exercise initially
- The anaerobic contribution to the total energy cost of exercise
78
Oxygen Debt
- After exercise, oxygen uptake remains above preexercise levels for a time according to the length and intensity of the exercise
- AKA Recovery O2 or Excess Postexercise Oxygen Consumption (EPOC)
79
Interval Training
A method that emphasizes bioenergetic adaptations for a more efficient energy transfer within the metabolic pathways by using predetermined intervals of exercise and work periods
80
Work-to-Rest Ratios
Predetermined intervals of exercise and rest periods
81
High-Intensity Interval Training (HIIT)
Involves brief repeated bouts of high-intensity exercise with intermittent recovery periods
82
Variables of HIIT
- Intensity of the active portion of each duty cycle
- Duration of the active portion of each duty cycle
- Intensity of the recovery portion of each duty cycle
- Duration of the recovery portion of each duty cycle
- Number of duty cycles performed in each set
- Number of sets
- Recovery intensity between sets
- Mode of exercise for HIIT
83
Interval training profile for 90-100% of max power
- Primary System Stressed: Phosphagen
- Typical Exercise Time: 5-10 s
- Range of Work-to-Rest Period Ratios: 1:12 to 1:20
84
Interval training profile for 75-90% of max power
- Primary System Stressed: Fast glycolysis
- Typical Exercise Time: 15-30 s
- Range of Work-to-Rest Period Ratios: 1:3 to 1:5
85
Interval training profile for 30-75% of max power
- Primary System Stressed: Fast glycolysis and oxidative
- Typical Exercise Time: 1-3 min
- Range of Work-to-Rest Period Ratios: 1:3 to 1:5
86
Interval training profile for 20-30% of max power
- Primary System Stressed: Oxidative
- Typical Exercise Time: >3 min
- Range of Work-to-Rest Period Ratios: 1:1 to 1:3
87
Combination Training
- AKA cross-training
- A style of training where aerobic endurance training is added to the training of anaerobic athletes
- Thought to improve recovery, since it is thought recovery relies on aerobic mechanisms
