Cardio-Respiratory physiology & training Flashcards
1
Q
What are we identifying as critical for all bioenergetic systems?
A
The rate-limiting factors.
We care about the ones that will be affected through training.
2
Q
What is the goal regarding rate-limiting factors and training?
A
The goal is to understand how we can benefit the human system through semi-permanent applications by training rate-limiting factors like the presence of certain enzymes that increase with appropriate training.
3
Q
Why is understanding muscle contraction important for exercise programming?
A
Understanding how and when muscles are contracting, and how hard they contract (kinetics), allows the principle of specificity to drive exercise programming decisions.
4
Q
What is the ultimate goal of all bioenergetic systems?
A
The ultimate goal is to synthesize ATP.
5
Q
Briefly outline the first 5 steps of muscle contraction according to the lecture.
A
- A nerve impulse enters the presynaptic terminal (nerve) of the neuromuscular junction.
- The impulse causes Ach to be released from the synaptic vesicles in the axon terminal.
- Ach diffuses across the synaptic cleft and opens Na+ channels in muscle membranes.
- Na+ enters the muscle cell and depolarizes it.
- ‘T’ tubules carry impulses into the sarcoplasmic reticulum and release Ca2+ ions.
6
Q
What is released from the synaptic vesicles during muscle contraction?
A
Acetylcholine (Ach) is released.
7
Q
What does Ach do in the muscle membrane?
A
Ach diffuses across the synaptic cleft and opens Na+ channels.
8
Q
What occurs when Na+ enters the muscle cell?
A
The muscle cell is depolarized.
9
Q
What role do ‘T’ tubules play in muscle contraction?
A
‘T’ tubules carry impulses into the sarcoplasmic reticulum and release Ca2+ ions.
10
Q
Briefly outline steps 6-10 of muscle contraction.
A
- Ca2+ enters the individual muscle fibrils and binds to troponin molecules on tropomyosin strands.
- This reaction moves the strand and results in exposing the binding sites.
- Myosin binds to actin forming cross-bridges that ATP can bind to.
- ATP breaks down, releasing energy, causing cross-bridges to pull the actin strand.
- Another ATP binds to myosin cross-bridge for the recovery stroke.
11
Q
Briefly outline the final 2 steps of muscle contraction.
A
- When the action potential ends, Ca2+ ions are pumped back into the sarcoplasmic reticulum.
- Tropomyosin covers the binding sites and myosin can no longer bind.
12
Q
Why are ions like sodium (Na+), potassium (K+), and calcium (Ca2+) important in muscle contraction?
A
These ions play crucial roles in nerve impulse transmission, muscle cell depolarization, and the binding of actin and myosin.
13
Q
What is bioenergetics?
A
Bioenergetics is the term for the event of all the processes synthesizing ATP.
14
Q
What two systems need to be conditioned appropriately for effective performance in any activity?
A
The neuromuscular system and the cardiovascular system need to be conditioned appropriately.
15
Q
What are the three main bioenergetic systems discussed?
A
The three main bioenergetic systems are:
- Creatine phosphate (ATP-CP)
- Glycolysis
- Oxidative phosphorylation
16
Q
What is the role of ATP in the cross-bridging cycle and muscle relaxation?
A
ATP is required for the cross-bridging cycle and for relaxation.
17
Q
What is the general function of enzymes?
A
Enzymes are proteins that catalyze reactions.
18
Q
What are the two main ways enzymes function that are most important for this course?
A
- Catabolism: Splitting a molecule into two or more molecules, releasing energy.
- Synthesis: Taking two or more component molecules and combining them, requiring energy to be stored in the new molecule.
19
Q
What happens to energy when a molecule is metabolized (broken down)?
A
Energy is released.
20
Q
What happens to energy when a molecule is synthesized (built up)?
A
Energy is required and stored in the molecule.
21
Q
What are high-energy phosphates?
A
The three phosphate ions attached to adenosine in ATP store large amounts of energy and are called high-energy phosphates.
22
Q
Can muscle tissue directly use ADP or AMP for energy?
A
No, muscle tissue can only use ATP. ADP and AMP must be resynthesized back into ATP.
23
Q
Describe the creatine phosphate system. Does it require oxygen?
A
The creatine phosphate system (ATP-CP or PCr) is the fastest bioenergetic system and does not require oxygen (anaerobic) to create muscular work.
24
Q
How is creatine phosphate formed? What enzyme catalyzes this?
A
Creatine phosphate is formed from free creatine (or creatine) and a phosphate ion, catalyzed by the enzyme creatine kinase.
25
What is significant about creatine kinase in relation to training?
There is evidence that exercise can increase the amount of creatine kinase in the muscles.
26
What are the limitations of the creatine phosphate system?
The limitations are the amount of creatine kinase in the muscle and the amount of creatine phosphate in the muscle.
27
How can total creatine levels in the muscle be increased?
Total creatine levels can be increased through exercise training, consuming more creatine in the diet (e.g., fish), or taking creatine supplements.
28
What happens to ATP and PCr levels during very short duration, maximal or high-intensity exercise?
Significant losses in ATP and PCr occur in the muscles being used.
29
Describe the initial changes in ATP and creatine phosphate levels during maximal exercise.
There is a sharp drop in ATP in the first couple of seconds. ATP levels then stay relatively constant for about 10-20 seconds while creatine phosphate levels sharply decline as it donates phosphate to ADP.
30
What happens when creatine phosphate levels are depleted?
Once creatine phosphate is expended, ATP levels drop again, leading to muscle failure or exhaustion.
31
Describe glycolysis. Does it require oxygen?
Glycolysis is another anaerobic (does not use oxygen) bioenergetic system.
32
What is the starting material and end product of glycolysis? What else is produced?
Glycolysis takes glucose or glycogen (carbohydrates) and breaks them down into two pyruvate molecules. It also produces ATP, NADH, and hydrogen ions (H+).
33
What are the two main limiting factors for glycolysis?
The two main limiting factors are the availability of glucose and the enzyme phosphofructokinase (PFK).
34
What is significant about phosphofructokinase (PFK) in relation to training?
The amount of PFK can be increased with training, allowing for more catalyzed glycolytic reactions.
35
Why is it necessary to remove the hydrogen ion from NADH produced during glycolysis? What are the two main ways this can happen?
The amount of NAD+ in the muscle is limited, and the hydrogen ion must be removed from NADH to regenerate NAD+ so glycolysis can continue. The two ways are:
- Production of lactate.
- Involvement of oxidative phosphorylation.
36
Describe lactate production. Does it require oxygen? What enzyme catalyzes it?
The production of lactate is the fastest method of resynthesizing NAD+ and does not require oxygen. The enzyme lactate dehydrogenase (LDH) catalyzes the reaction between pyruvate and NADH to produce lactate.
37
Why is the accumulation of hydrogen ions (H+) during glycolysis a concern?
Hydrogen ions are acidic and their accumulation can prevent muscles from being able to contract.
38
How can the body buffer the accumulation of hydrogen ions in muscles?
Muscles contain bicarbonates that react with hydrogen ions, neutralizing the acid and releasing carbon dioxide, which is then removed through respiration.
39
How can the ability to buffer hydrogen ions in muscles be increased?
It can be increased through exercise training (increasing muscle bicarbonate levels) and potentially through bicarbonate intake (though this has practical limitations).
40
Describe oxidative phosphorylation. Does it require oxygen? What are its two main steps?
Oxidative phosphorylation is an aerobic (requires oxygen) method of synthesizing ATP. Its two main steps are the Krebs cycle (citric acid cycle) and the electron transport chain.
41
Where do the creatine phosphate and glycolytic systems primarily occur within the muscle cell?
They occur in the sarcoplasm (the fluid within the muscle cells).
42
Where does oxidative phosphorylation occur within the muscle cell?
It occurs in the mitochondria.
43
What is the role of acetyl-coenzyme A in the Krebs cycle? Where can it be synthesized from?
Acetyl-coenzyme A is a critical player in the Krebs cycle. It is synthesized from pyruvate (from glycolysis) or fatty acids. It can also be produced from the breakdown of amino acids, though this is less common.
44
What are the key products of the Krebs cycle that then enter the electron transport chain?
NADH and FADH (flavin adenine dinucleotide with a hydrogen ion) are produced in the Krebs cycle and then go into the electron transport chain.
45
What are the three main factors that limit the rate of the Krebs cycle?
The three main factors are:
- The number of mitochondria.
- The enzyme citrate synthase.
- The enzyme succinate dehydrogenase.
46
What is significant about the number of mitochondria and the enzymes citrate synthase and succinate dehydrogenase in relation to training?
Training increases the number of mitochondria and the amount of citrate synthase and succinate dehydrogenase in the muscles.
47
What happens to NADH and FADH in the electron transport chain? Why is this important?
In the electron transport chain, NADH and FADH are re-synthesized back to NAD+ and FAD. This is important because NAD+ is needed for glycolysis and both NAD+ and FAD are needed for the Krebs cycle.
48
Where does the electron transport chain occur? What are its limiting factors?
The electron transport chain also occurs in the mitochondria. Its limiting factors are the number of mitochondria present and the presence of oxygen in the mitochondria.
49
How is oxygen delivered to the mitochondria?
Oxygen is inhaled into the lungs, diffused into the bloodstream, and is delivered by the red blood cells. More oxygen needs to be in the blood, which is then delivered to the working muscles.
50
What is the primary bioenergetic system contributing to ATP synthesis during steady-state activity? What is the approximate percentage?
During steady state, the primary contributor is oxidative phosphorylation, accounting for 90% or more.
51
What happens to the contribution of bioenergetic systems as exercise intensity increases beyond steady state?
Oxidative phosphorylation may not be able to keep up with ATP demand, and glycolysis and the ATP-CP system become more important. At the highest intensities, the ATP-CP system is the most important.
52
During non-steady state activity, which bioenergetic systems may contribute to ATP synthesis?
All three bioenergetic systems (ATP-CP, glycolysis, and oxidative phosphorylation) may contribute.
53
How does the relative contribution of ATP-CP, glycolysis, and aerobic (oxidative) systems change as the duration of non-steady state activity increases?
- ATP-CP decreases as activity gets longer.
- Aerobic (oxidative) increases as activity gets longer.
- Glycolysis remains relatively similar in its contribution.
54
What factors limit the ability of the ATP-CP system to synthesize ATP? How can these be improved by exercise?
Limitations: Amount of creatine phosphate and creatine kinase in the muscle. Improvement: High-intensity exercise can increase total creatine kinase and creatine phosphate.
55
What factors limit the ability of glycolysis to synthesize ATP? How can these be improved by exercise?
Limitations: Availability of glucose and the enzyme phosphofructokinase (PFK). Improvement: Training can increase the amount of PFK.
56
What factors limit the ability of oxidative phosphorylation to synthesize ATP? How can these be improved by exercise?
Limitations: Number of mitochondria, the enzymes citrate synthase and succinate dehydrogenase, and oxygen delivery and extraction. Improvement: Endurance training increases mitochondria, these enzymes, and improves oxygen delivery and extraction.
57
How do the limiting factors of bioenergetic systems relate to needs analysis and exercise programming?
Understanding the limiting factors helps determine how to improve specific aspects of performance (e.g., anaerobic power, anaerobic threshold, aerobic power) and drives decisions about training intensity, duration, and volume to target the appropriate bioenergetic systems.
58
What is the SAID principle and how does it relate to training adaptations?
SAID stands for Specific Adaptations to Imposed Demands. Adaptations are specific to the bioenergetic system, motor units, and muscles that are trained.
59
What is a motor unit? How does it relate to training adaptations in different muscle fiber types?
A motor unit is a motor neuron and all the muscle fibers it innervates. To increase creatine phosphate or enzyme amounts in fast glycolytic (Type II) motor units, those specific motor units must be activated during training.
60
What are peripheral adaptations to endurance training? Give examples.
Peripheral adaptations occur at the muscle level, involving the extraction and utilization of oxygen. Examples include increased myoglobin in specific muscles and increased capillarization (number of capillaries).
61
What are central adaptations to endurance training? How do they differ from peripheral adaptations?
Central adaptations influence the ability to intake and transport oxygen to the whole system and are not specific to the muscles used. Peripheral adaptations are specific to the working muscles.
62
What is the Fick equation? What do its components represent?
The Fick equation describes the volume of oxygen consumed (VO2). It is: VO2 = Cardiac Output x (a-vO2 difference).
- Cardiac Output (blood pumped by the heart per minute) is the central factor.
- Arterial-venous oxygen difference (a-vO2 diff) (how much oxygen is extracted by the tissues) is the peripheral factor.
63
How does training affect myoglobin levels in muscles?
Training increases the amount of myoglobin in specific muscles that are being trained, leading to more oxygen transfer from hemoglobin to myoglobin.
64
What is capillarization? Why is it important for oxygen delivery to muscles?
Capillarization is the increase in the number of capillaries in muscles. More capillaries increase the surface area for oxygen transfer from hemoglobin to myoglobin.
65
What is cardiac output? How is it calculated?
Cardiac output is the amount of blood pumped by the heart per minute. It is calculated by Heart Rate x Stroke Volume.
66
What is stroke volume? How is it calculated?
Stroke volume is the amount of blood pumped from the left ventricle in a single heart beat. It can be calculated as End Diastolic Volume (EDV) - End Systolic Volume (ESV).
67
How does endurance training affect end diastolic volume (EDV)? What is the consequence?
Trained individuals have a higher EDV at rest and during exercise. This allows for more blood to be pumped out of the ventricle per beat, leading to a higher stroke volume.
68
How does endurance training affect resting heart rate and heart rate at a given submaximal intensity? Why?
Endurance training typically leads to a lower resting heart rate and a lower heart rate at the same submaximal exercise intensity. This is because a higher stroke volume allows the heart to pump the same amount of blood with fewer beats.
69
What is myocardial compliance? How does endurance training affect it and what are the benefits?
Myocardial compliance is the ability of the left ventricle to stretch. Endurance training increases myocardial compliance, allowing the ventricle to fill with more blood (higher EDV) and potentially.
70
What is myocardial compliance?
Myocardial compliance is the ability of the left ventricle to stretch. Endurance training increases myocardial compliance, allowing the ventricle to fill with more blood (higher EDV) and potentially enhancing the stretch-shortening cycle for a more forceful contraction.
71
What is the relationship between aerobic power (VO2 max) and training volume?
Generally, increasing training volume leads to increases in VO2 max, especially in the initial stages of training. However, this relationship is not linear, and VO2 max will eventually plateau, even with further increases in volume.
72
What is the approximate upper limit for improvements in VO2 max from baseline through training?
VO2 max can typically only go up about 50% from an active healthy baseline.
73
Once VO2 max plateaus with increasing training volume, how can performance be further improved?
Further improvements likely require addressing technique and the intensity of training, potentially focusing on training at or just below the anaerobic threshold.
74
What is minute ventilation (pulmonary ventilation)?
Minute ventilation is the amount of breathing (volume of air inhaled or exhaled) per minute.
75
How does minute ventilation typically change with endurance training at submaximal exercise?
Minute ventilation tends to decrease at the same submaximal workload after endurance training, as the individual becomes more efficient at ventilation and oxygenation.
76
What is the ventilatory cost of exercise?
The ventilatory cost of exercise is the cost of oxygen consumed by the respiratory muscles. During maximal exercise, it's typically around 5-20% of total oxygen consumption, with around 10% being a common estimate.
77
What is the hypothesis behind respiratory muscle training for endurance athletes?
The hypothesis is that by improving the efficiency of respiratory muscles, less oxygen will be diverted away from the working locomotor muscles, potentially improving aerobic performance. However, the research is not conclusive in showing significant benefits for performance in healthy athletes.
78
What is the most precise method of prescribing cardiovascular intensity mentioned in the lecture?
The most precise method is as a percentage of VO2 max. Drawbacks include the need for expensive and time-consuming VO2 max testing and the fact that VO2 max can change with training, requiring periodic retesting.
79
Why is prescribing cardiovascular intensity based solely on heart rate considered the least precise?
Heart rate response is highly variable between individuals and is influenced by many factors. Estimating maximal heart rate (e.g., 220 - age) is not always accurate, and heart rate response to training also varies.
80
What is considered a practical and relatively precise method of prescribing cardiovascular intensity?
Measuring speed or power (velocity) is considered practical and reliable. Speed (or race pace) is relevant, easy to measure (stopwatch, speedometer), and directly relates to performance goals for many endurance athletes. Power meters also provide a solid, reliable measure of intensity.
81
What is the structure of a polarized training program for endurance athletes?
Polarized training involves spending most training time in very low intensity (zones 1 & 2) and a significant amount of time in high intensity (zones 4 & 5 or higher), with very little time spent in the threshold zone (zone 3). Traditional high-volume threshold training involved training mostly in zones 1 & 2 with a couple of days at threshold.
82
What is the rationale behind polarized training?
Polarized training allows for stressing different physiological systems on different days, promoting recovery. Zone 3 training can heavily tax both the glycolytic and oxidative systems without providing sufficient recovery for either, potentially leading to fatigue and overtraining.
83
How does the mode of training (general vs. specific) relate to the training zones in a polarized program?
Zones 1 & 2 (low intensity) primarily elicit central adaptations (improved oxygen intake and transport), so general modalities (running, cycling, swimming, etc.) can be used. Zones 3, 4, & 5 (higher intensities) elicit both central and peripheral adaptations, so the mode should be more specific to the muscles used in the performance.
84
For non-steady state sports, how does training mode evolve as competition approaches?
As competition nears, there is a greater emphasis on sport-specific training or modified versions of the game to facilitate the transfer of fitness gains to performance, involving the right muscles and movement patterns.
85
Why might zone 1 and 2 training have limited direct benefit for performance in non-steady state, high-intensity repetitive sports?
While zones 1 and 2 can benefit aerobic power and recovery, they don't directly address the metabolic and neuromuscular demands of high-intensity, intermittent activities as effectively as higher intensity training.
86
What is EPOC?
EPOC stands for Excess Post-exercise Oxygen Consumption. It represents the elevated oxygen consumption after exercise compared to resting levels, which is needed to restore the body to its pre-exercise state.
87
What are the two main phases of EPOC?
The two main phases are the fast phase and the slow phase. The fast phase involves resynthesizing ATP and creatine phosphate and restoring pre-exercise levels of these molecules. This typically occurs within a few minutes to an hour.
88
What occurs during the slow phase of EPOC?
The slow phase involves processes like the metabolism of lactate, muscle recovery (restoring ion balance like Na+/K+ and Ca2+), and other physiological processes. This phase can last for many hours (12-48) depending on exercise intensity and duration.
89
Describe the Cori cycle.
The Cori cycle occurs in the liver. It involves the conversion of lactate (from the blood) back into glucose through gluconeogenesis. This glucose can then be released back into the bloodstream.
90
What is a futile cycle?
A futile cycle is a set of metabolic reactions that start and end with the same molecule but result in a net loss of ATP. The combination of glycolysis and the Cori cycle (starting with glucose and ending with glucose) is an example, as both processes require ATP.
91
How might the Cori cycle be strategically utilized for body composition goals?
By delaying carbohydrate intake after intense exercise that relies on glycolysis, the body may utilize the Cori cycle to maintain blood glucose, leading to additional energy expenditure and potentially aiding in fat loss.
92
How might carbohydrate intake immediately after exercise affect the Cori cycle?
Immediate carbohydrate intake can provide glucose, reducing the need for the Cori cycle and potentially sparing ATP that would have been used for gluconeogenesis. This might be preferred for rapid recovery in athletes who train frequently.
93
How does exercise volume and intensity affect EPOC?
For the same volume, higher intensity results in a greater EPOC. Also, performing the same volume of exercise in two sessions per day can lead to a greater EPOC compared to a single session.
94
When designing a training program, how many parameters should typically be manipulated at a time?
It is generally recommended to manipulate only one parameter at a time (e.g., volume, intensity, frequency) to better understand which change is responsible for the observed adaptations and avoid confounding issues.
95
How can polarizing training potentially increase training frequency and volume?
By alternating between very low and very high intensity, different physiological systems are stressed on different days, potentially allowing for more frequent training sessions without overtaxing the same system continuously, thus enabling higher overall training volume.
96
What is the general trend between training volume and performance over many years of training?
For many years of training, higher training volume is often associated with better performance.
97
What should be the primary driver of training prescription after deciding on the mode of exercise?
Intensity.
98
What is the relationship between training intensity, volume, and frequency?
These factors are interdependent. If intensity increases while frequency remains the same, volume may need to decrease, and vice versa, to manage overall training stress.
