Module 1: Energy Systems During Exercise Flashcards
1
Q
What determines the way in which energy is provided?
A
intensity and duration
2
Q
What is ATP
A
usable form of energy in the body.
3
Q
How is food used for energy?
A
The energy from foods that we eat has to ultimately be converted into ATP before the potential energy can be used.
4
Q
How does ATP provide energy?
A
Energy is released from ATP by breaking down the bonds that hold this compound together via ATP-ase enzymes
5
Q
What kind of reaction is the breakdown of ATP
A
exothermic reaction
6
Q
What is the importance of ATP resynthesis?
A
Small amounts of ATP are stored with muscle fibres and stored ATP is used up very quickly (2-3 seconds) and therefore needs to be replenished immediately for movement to continue. Re-synthesis of ATP is done through the joining of ADP and a single phosphate.
7
Q
What kind of reaction is ATP resynthesis?
A
Endothermic - this is a chemical reaction which absorbs energy.
8
Q
What are the energy systems for ATP resynthesis?
A
- ATP-PC System (Phosphagen System)
- Glycolytic System (Anaerobic Glycolysis)
- Aerobic System
9
Q
The point at which an athlete moves from one energy system to another
A
threshold
10
Q
What does threshold depend on?
A
exercise intensity and fuel available
11
Q
Activity that is performed at a low to moderate intensity over a sustained or prolonged period of time.
A
Supported by the aerobic system
12
Q
Aerobic system activity
A
Activity that is performed at a low to moderate intensity over a sustained or prolonged period of time.
13
Q
What does depleted ATP stores cause?
A
Depleted ATP stores trigger the release of the enzyme, creatine kinase, which causes phosphocreatine (PC) that is stored in skeletal muscle to be broken down anaerobically.
14
Q
Another name for PC
A
Creatine Phosphate (CP)
15
Q
Where do we get creatine from?
A
Creatine produced by the body in the liver and kidneys from dietary creatine sources (meat, fish, poultry) and dietary sources of arginine, glycine, and methionine.
16
Q
Can support powerful muscle contractions but only 2-3 seconds.
A
Stored ATP
17
Q
Process if the ATP-PC system
A
- Non-phosphorylated creatine (Cr) is released from the liver into the blood stream and transported to muscle cells.
- Once inside muscle cells, it is transformed into phosphocreatine by the enzyme complex creatine kinase.
- PCr can anaerobically donate a phosphate group to ADP in muscle to form ATP and generate the energy needed to support movement.
18
Q
providing contractions of high power
A
ATP-PC System
* 100 m run
* a short burst of intense activity during a longer game - A fast break in basketball
19
Q
Length of the ATP-PC system
A
There is only enough PC to last for up to 10 seconds
20
Q
When can ATP-PC system be replenished?
A
it can only be replenished when the intensity of the activity is sub-maximal.
21
Q
the point at which the ATP-PC energy system is exhausted and the glycolytic system takes over.
A
ATP-PC/Glycolytic Threshold
22
Q
Advantages of ATP-PC system
A
- ATP can be rengerated rapidly
- PC stores replenished within 3 minutes
- No fatigueing by-products
- The ATP-PC system can be extended through the uses of a creatine supplement
23
Q
Disadvatages of ATP-PC system
A
- Limited supply of PC in the body
- 1 ATP molecule regenerated for 1 molecule of PC
- Regneration can only take place in the presence of oxygen
24
Q
What has been linked to enhanced exercise capacity?
A
Maximal body stores of creatine
* High intensity and really short term such as lifting a heavy weight. If you can lift a heavy weight more times till you fatigue due to PC more you will see hypertrophy and potential fitness gain
25
How much does diet provide to creatine stores?
Diet alone provides about 1–2 g/day of creatine resulting in muscle creatine stores at 60–80% maximal saturation.
26
Theoretical basis for creatine supplementation
PCr stores limit maximal ATP production and performance during high intensity, short time activity (e.g. sprinting). Therefore supplementation with PCr will increase cellular PCr levels and enhance exercise performance.
27
What can creatine supplementation improve?
* increase muscle creatine content
* improve exercise capacity
* improve sport performance.
28
Creatine supplementation use for clinical therapeutic health benefits
* Creatine deficiency syndromes
* Myocardial ischemia and/or stroke
* Neurodegenerative diseases
29
Ergogenic effects of Creatine supplementation
* Increases in performance and strength in short-duration, maximal- intensity exercises
* May increase in lean body mass through abilty of athlete to recover quickly and then lift again
* May prevent loss of strength as a result of aerobic activity when combined with anaerobic activities in recreational athletes
30
What are the performance benefits of creatine supplementation?
* 1-repetition maximum
* muscular power
* number of repetitions
* muscular endurance
* speed
* total force.
31
Who is most likely to get benefit from creatine supplementation?
athlete with a low baseline level of creatine will likely benefit more whereas athletes with a higher baseline level of creatine before supplementation are less likely to derive benefit from supplement
* hence difference between "responders" and "non-responders"
32
Creatine supplementation protocol
33
Potential side effects of creatine supplementation
* Muscle cramps with deposition of creatine
* Over-use injuries with mismatch between creatine and ability of body
* Impaired hydration status and fluid retention eith interference in osmotic balance
* Doping violations; not always just creatine - PCr supplements have been the subject of “off label” additions of WADA banned substances.
* Decreased focus on healthy eating and other critical aspects of HIIT performance.
34
process of glucose breakdown in the absence of oxygen and the production of lactic acid from pyruvic acid.
anaerobic glycolysis
35
Key enzymes of the glycolytic system
* phosphofructokinase
* lactate dehydrogenase
36
The body adopting an alternate metabolic route to get rid of lactate, and keep producing energy anaerobically.
Cori Cycle
37
Lactate, produced by the muscles is converted to glucose by the liver and fed back to working muscles to serve as a substrate for ATP synthesis.
Cori Cycle
38
Lactate/Anaerobic Threshold
During intense activity lactate accumulates in working muscles. At the same time, the body cannot produce ATP quickly enough to meet its needs.
39
End product of the Cori cycle
glucose
40
When is the Cori cycle stimulated?
Anaerobic glycolysis
41
the exercise intensity at which the blood concentration of lactate begins to increase rapidly
Onset of Blood Lactate Accumulation (OBLA)
42
Lactate Threshold (LT) Training
Trained athletes can clear lactate using the Cori Cycle more effectively than untrained individuals.
43
What happens if lactate synthesis exceeds ability of cori cycle to clear it?
lactate and H+ ion accumulate in muscle causing fatigue and a reduction in performance.
44
The point after which lactate synthesis exceeds lactate clearance.
Lactate (Anaerobic threshold) threshold
45
How long will the glycolytic system be able to resynthesize ATP?
Will continue for up to 3 minutes but peaks at 1 minute.
* E.g. Goal off the bench in hockey
46
What is necessary to support the glycolytic system?
The body must have adequate CHO available to support glycolysis – either as blood glucose or glycogen.
47
Key system for high intensity and intermediate time activity
glycolytic system
48
the point at which the intensity of activity begins to decline (but not stop) and plateau and the rapid energy production of the Glycolytic system is no longer needed.
Glycolytic/Aerobic Threshold
* Sufficient oxygen will be available throughout to allow for ATP re- synthesis.
49
Advantages of glycolytic system
* ATP can be regenerated quickly due to few chemical reactions needed
* With oxygen present, lactate is coverted back into glycogen
* This system is useful for producing an extra burst of energy
50
Disadvantages of glycolytic system
* lactic-acid is by-product
* only a small maount of energy is released from glycogen while under anaerboci conditions
51
Limits to glycolytic energy production
H+ production reduces muscle pH thus messing with the buffering system
52
What can help promote anaerobic energy production?
Improving the buffering capacity of the muscle to better handle the changes in pH
* training
* nutrition
53
training methods to promote the glycolytic system
high-intensity interval training increases muscle buffering capacity and high-intensity exercise performance
54
nutrition methods to promote the glycolytic energy production
* Bicarbonate loading - improve performance
* beta-alanine - improve muscle buffering capacity and high-intensity exercise performance
* creatine - improve buffering capacity
55
Use of bicarbonate loading to promote glycolytic energy production
Orally loading with bicarbonate (baking soda) has been proposed as a way to limit the fatigue generated by production of lactic acid and H+ ions in muscle during high intensity activity fueled by glycolysis.
56
What type of performance is bicarbonate loading recommended for?
exhuastive exercise lasting between 1-7 minutes
57
Theoretical basis for bicarbonate loading
Orally loading with bicarbonate will, in turn, temporarily increases blood bicarbonate to acutely enhance extra-cellular buffering of the efflux of H+ ions coming from contracting muscle.
58
thought to reduce the fatigue and exercise capacity drop off associated with intense activity where there is production of large amounts of H+ ions via anaerobic glycolysis
Bicarbonate loading
* orally
59
Evidence of bicarbonate loading
Research shows that bicarbonate loading is associated with enhanced performance (~2% gain) during short-term, high- intensity sprints lasting ~60 s in duration, with a reduced efficacy as the effort duration exceeds 10 min.
* Drop off in benefits is seen as early as 4 min
60
What has a critical impact on the performance gains driven by supplementation with NaHCO3?
duration and intensity of exercise
61
What has a critical impact on the performance gains driven by supplementation with NaHCO3?
duration and intensity of exercise
62
Sodium bicarbonate loading protocol
* Single, acute NaHCO3 dose of 0.2–0.4 g/kg consumed 60– 150 min prior to exercise.
* Split doses taken over a time period of 30–180 min prior to exercise, for total of 0.2-0.4 g/kg
* Serial loading with 3–4 smaller doses per day for 2–4 consecutive days prior to an event.
63
Potential side effect of biocarbonate loading
Profound GI distress (nausea, explosive diarrhea, pain)
64
Strategies to minimize GI upset from sodium bicarbonate loading
* Co-ingestion of NaHCO3 with a small, carbohydrate-rich meal (~1.5 g/kg BM carbohydrates),
* Use of sodium citrate as an alternative to NaHCO3
* Split dose or stacking strategies to dosing.
65
Recommendations for how to use bicarbonate loading
thorough investigation into the best individualized strategy is recommended **prior** to use in a competition setting.
* Practice in training first!!`
66
What does aerobic system need to function?
oxygen
* Sufficient oxygen availability to support aerobic metabolism occurs when the intensity of activity is low-moderate even if the duration of activity may be very long.
67
ATP produced with complete oxidation of glucose
up to 38 molecules of ATP
68
What are the 3 stages of the aerobic system?
* Stage 1 - glycolysis
* Stage 2 - Krebs/CAC
* Stage 3 - ETC
69
Stage 1 of the aerobic system
Same as anaerobic glycolysis but occurs in the presence of oxygen where the pyruvate is converted to acetyl-CoA which then moves into the mitochondria within muscle cell for further processing
70
Stage 2 of the glycolytic
Krebs cycle/ CAC
Once pyruvate enters the mitochondria it is quickly converted to Acetyl-CoA through the Krebs cycle producing two moelcules of ATP as well as CO2 and hydrogen is taken to the ETC via NADH
71
3rd stage of the aerobic system
ETC
hydrogen from the CAC via NADH (and FADH) is carried to ETC which occurs in the cristae of the mitochondria. The hydorgen is taken off to become ions and electrons and these are charged with potential energy and are oxidized to form water while providing energy to re-synthesize ATP. 34 molecules of ATP are formed here
72
What enhances the body's ability to utlizie the available energy systems?
Training!
73
What else can be used as an energy source in the aerobic system?
Fats can also be used as an energy source in the aerobic system.
* The Krebs Cycle and the Electron Transport Chain can metabolize fat as well as carbohydrate to produce ATP.
74
Predominant energy source in long duration activities
fatty acids since more ATP can be made from one molecule of fatty acids than from one molecule of glycogen but the intensity must be low.
75
Advantages of the aerobic system
* More ATP produced than anaerobic systems
* No fatiguing by-products (CO2 and water are exhaled)
* plenty of glycogen and TAG stores
76
Disadvantages of the aerobic system
* It cantake oxygen a while to become available
* fatty acid transport to muscle sites are slow
77
process of converting excess glucose into glycogen
glycogenesis
78
where is glycogen stored?
Glycogen can be stored in the liver and the muscle in limited capacity
* Muscle glycogen (~460-520 g) – only used by the muscle for energy
* Liver glycogen (~80 g) – can leave the liver as blood glucose to be used by the brain and other tissues
79
Where can fat be stored?
several locations throughout the body including
* subcutaneous adipose
* visceral adipose
* muscle
80
source of fuel for muscles to generate ATP, primarily during endurance exercise providing FFA for aerobic metabolism
Intramuscular Triglycerides (IMTG)
81
Approximate storage of IMTG
~200 g (1800 kcal) stored in the muscle
82
An adaptation that occurs with exercise training, particularly endurance exercise training, to improve capacity to store glycogen
Carbohydrate loading
83
How to take advantage of CHO loading
Consume adequate CHO
84
the situation where the body can no longer generate sufficient ATP owing to a lack of glucose from both glycogen and blood glucose
hitting the wall
85
limiting substrate in aerobic metabolism
Carbohydrate
* “Fat burns in the flame of carbohydrate.” - You cannot complete the ß oxidation of fats and the full Aerobic System without first completing glycolysis.
86
Limits of Aerobic energy production
* hitting the wall
* ATP production from fat is slow
* CHO is limiting substrate
87
If adequate carbohydrate to fuel either anaerobic or aerobic metabolism is not available, the athlete can experience this phenomenon
“Hitting the Wall,” or “Bonking.”
88
How is hitting the wall characterized?
characterized by glucose depletion (blood levels and glycogen) which, in turn, produces severe hypoglycemia
89
Symptoms if hitting the wall
Severe fatigue, dizziness, light-headedness, tunnel- vision, disorientation, anxiety, nervousness, irritability, hostility, seizures, coma.
90
What can prevent athletes from Hitting the Wall.
* Training diet
* pre- event eating strategies
91
Following intense physical activity, the body continues to consume high levels of oxygen and reflect heightened levels of metabolism even though the activity has ceased.
Excess Post-Exercise Oxygen Consumption (EPOC)
92
Other names for EPOC
“afterburn,” or “oxygen debt”
93
What does EPOC reflect
Reflects the work of the body to repair and replenish itself and return to its pre-exercise state.
* EPOC helps the body recover.
94
Functions EPOC supports after intense activity
* production of ATP to replace the ATP used during the workout
* Re-synthesis of muscle glycogen from lactate via the Cori Cycle
* Restoration of oxygen levels in venous blood, skeletal muscle blood and myoglobin
* Repair of muscle tissue damaged during the workout
* Restoration of body temperature elevations to normal/resting levels
* Increased metabolic rate and an elevation of resting energy expenditure
95
Factors Effecting the Magnitude and Duration of the EPOC
* Exercise intensity
* Duration of exercise
* Training Status
* gender
* intermittent vs. single bouts of exercise
96
How does exercise intensity effect EPOC?
* High intensity = Higher EPOC
* Activity at levels approaching the athlete’s Anaerobic Threshold.
97
How does duration of activity effect EPOC?
Given sufficient aerobic exercise intensity, exercise duration is an important factor influencing EPOC.
98
How does training status effect EPOC?
The magnitude of EPOC in trained athletes may be smaller than in un-trained individuals.
* Several studies have reported a more rapid fall in EPOC and a shorter duration of EPOC in trained subjects
* but many untrained people might not be conditioned enough to get to the intensity to even utlizie this concept
99
Problem with Crossfit for getting EPOC
CrossFit could generate an EPOC but someone struggling with weight this is probably not a good choice as they would likely hurt themselves
100
What is the most significant factor in boosting post-exercise metabolism?
exercise intensity
101
How does gender effect EPOC?
* Research shows that energy expenditure with women at rest and during exercise varies with the menstrual phase .
* Typically, resting energy expenditure is lowest one week before ovulation and highest during the 14-day luteal phase following ovulation, thus accordingly affecting EPOC.
* Few controlled studies have been conducted to compare EPOC in men and women. Therefore the gender effect on EPOC is not fully understood.
102
How does Intermittent versus Single Bouts of Exercise effect EPOC?
Several studies have concluded that intermittent aerobic exercise bouts elicit a greater EPOC response when compared to continuous exercise bouts.
103
most effective way to stimulate the EPOC effect
High-Intensity Interval Training (HIIT)
104
What happens during HIIT?
ATP is produced by the anaerobic pathways during HIIT. Once that ATP is exhausted, the ATP must be replenished for the athlete to continue. So, during the rest interval of a HIIT workout, the body reverts to aerobic metabolism and tries to replace its ATP losses
* This works to some degree – enough to complete the next interval – but the body will remain (overall) in a state of oxygen debt or deficit.
105
the difference between the volume of oxygen consumed during exercise and the amount that would be consumed if energy demands were met through only the aerobic energy pathway.
Oxygen debt/ deficit
106
The larger the oxygen deficit the ?? the EPOC and its effects.
The larger the oxygen deficit the **greater** the EPOC and its effects.
