Chapter 7 - Energy Transfer During Physical Activity Flashcards
What is the ATP-PCr Energy System Responsible for?
High-Intensity Exercise of Short Duration
- Under 10 seconds
How much ATP and PCr does each kg of skeletal muscle contain?
ATP
- 3-8mmol
PCr
- 12-48mmol
What is the Short-term Glycolytic Energy System responsible for?
Intense, Short-duration exercise
What results from short-term glycolytic energy systems?
- lactate formation
When would there be rapid and large accumulation of blood lactate?
Maximal Exercise of 60-180 seconds
What happens when you decrease intensity of exercise to extend duration?
- Depressed lactate accumulation rate
- Reduced final blood lactate levels
Does blood lactate accumulate at all exercise levels?
- NO
When does blood lactate not accumulate during exercise?
Light/Moderate Exercise
- Under 50% aerobic capacity
Why does blood lactate not accumulate during light/moderate exercise?
- Lactate production equals lactate clearance
- Oxygen-consuming reactions adequately meeting exercise energy demands
What have tracer studies that label the carbon in glucose show about lactate?
- 70% oxidizes
- 20% converts to glucose in muscle/liver
- 10% synthesizes amino acids
Why would a trained person perform steady-rate aerobic exercise at 80-90% of maximum aerobic capacity?
- Specific Genetic Endowment
- Specific local training adaptations that favour less lactate production
- More rapid rate of lactate removal at any exercise intensity
What is the difference between lactate concentration for trained and untrained individuals?
Untrained
- Early lactate threshold
- Lower max lactate tolerance
Trained
- Steep curve
- Later lactate threshold
- High tolerance
What factors are related to the lactate threshold?
- Low tissue oxygen
- Reliance on Glycolysis
- Activate fast-twitch muscle fibers
- Reduced lactate removal
What factors contribute to higher blood lactate levels during maximal exercise due to specific sprint-power anaerobic training? Are these factors permanent?
Factors
- Improved motivation
- Increased intramuscular glycogen stores
- Increase in Glycolytic-Related Enzymes
Permanent
- NO, reduce when training ceases
What does lactate shuttling between cells do?
- enables glycogenolysis in one cell to supply other cells with fuel for oxidation
Other than lactate production, what is the muscle also a major site for?
- Removal of lactate via oxidation
What happens to glucose that is derived from lactate?
- Returns in blood to skeletal muscle for energy metabolism
- Synthesizes to glycogen for storage
What is the long-term energy system?
- The Aerobic System
What provides nearly all the energy transfer when intense exercise continues beyond several minutes?
- Aerobic Metabolism
What happens with oxygen uptake during exercise?
Initially
- Rises exponentially
Eventually
- Plateaus, then remains in steady-rate for duration of effort
Explain steady-rate aerobic metabolism
- balance between energy required and ATP production in aerobic reactions
What is the relation between lactate and steady-rate conditions?
- No appreciable blood lactate accumulation
What 2 factors limit steady-rate metabolism?
- fluid loss/electrolyte depletion
- Balance between glycogen reserves in liver for CNS and muscle to power exercise
What two factors help explain athlete’s high steady-rate levels?
- High capacity for oxygen delivery to working muscles
- High capacity of active muscles to use oxygen
Describe the oxygen deficit?
- the difference between total oxygen consumed and total that would be consumed with immediate steady-rate uptake
What does the Oxygen Deficit represent?
- immediate anaerobic energy transfer from the hydrolysis of intramuscular high-energy phosphates and glycolysis until steady-rate energy transfer meets current energy demands
How does the energy for exercise occur?
- smooth blending and considerable overlap of different modes of energy systems
What is the oxygen uptake fast component?
- Exponential rise in oxygen uptake in first minutes of physical activity
- plateau around 3rd or 4th minute
What is unique about endurance-trained individuals regarding steady-rate?
Compared to sprint-power athletes, cardiac patients, older adults, and untrained:
- Reach it more rapidly
- Smaller oxygen deficit
What causes a trained individual to consume a greater total amount of oxygen during steady-rate exercise? What else does it do?
Faster Aerobic Kinetic Response
- makes an anaerobic component of exercise energy transfer proportionally smaller
What three aerobic training adaptations facilitate the rate of aerobic metabolism when exercise begins?
- Rapid increases in muscle bioenergetics
- Rapid Increase in overall blood flow
- Disproportionally larger region blood flow to active muscle, complimented by cellular adaptations
What do the three aerobic training adaptations that facilitate the rate of aerobic metabolism when exercise begins do?
- Increase individual total capacity to generate ATP aerobically
What does a High VO2max require?
- Integrate and high-level responses of five diverse physiologic support systems
What 5 physiologic support systems must integrate and work at high levels to get a High VO2max?
- Pulmonary Ventilation
- Hemoglobin Concentration
- Blood Volume and Cardiac Output
- Peripheral Blood Flow
- Aerobic Metabolism
What four factors does Hill suggest that determine VO2max?
- Arterial O2 Saturation
- Mixed Venous Saturation
- O2 capacity of the Blood
- Circulation Rate
What quantitative estimate is made for arterial O2 saturation?
- Ventilation
What quantitative estimate is made for Mixed Venous Saturation?
- Central Blood Flow
What quantitative estimate is made for O2 capacity of the blood?
- Active Muscle Metabolism
What quantitative estimate is made for the circulation rate?
- Peripheral Blood Flow
Why are athletics used for study on exercise physiology?
- Simple, measurable, and constants
- Athletes: reduced danger (healthy)
- Exciting and new for physiology (more recruits)
Why are both muscle twitch fibers usually required for most sports?
- slow, sustained muscle action
- Short bursts of power
What do athletes who excel in different sports usually have with regard to muscle fiber type?
- a large percentage of specific muscle fiber type that supports that sport’s energy demand
Describe Fast-Twitch Muscle Fibers
Type II
- Rapid Contraction Speed
- High Capacity for Anaerobic ATP production
Type IIa
- High Aerobic Capacity
What type of movement are Type II muscle fibers good at?
- Change of pace
- stop and go
What type of muscle fiber is Fast-Twitch?
- Type II
Describe Slow-twitch muscle fibers
- Generate energy through aerobic pathways
- Slow contraction speed
What type of activity are Slow-twitch muscle fibers good for?
- Continuous activities
- Steady-rate aerobic energy transfer
What type of muscle fiber is a slow-twitch?
- Type I
What type and percentage of muscle fibers would a swim champion have?
Type II
- Fast-twitch
- 80%
What type and percentage of muscle fibers would an endurance cyclist have?
Type I
- Slow-twitch
- 80%
What is EPOC?
Excess Post-exercise Oxygen Consumption
What 7 things contribute to EPOC?
- Resynthesize ATP & PCr
- Resynthesize Lactate to Glycogen
- Oxidize Lactate for energy metabolism
- Restore Oxygen to Myoglobin and Blood
- Restore thermogenic effects of elevated core temp
- Thermogenic effect of hormones (catecholamines)
- Restore Elevated HR, VE, other physio function
Describe Steady-State Exercise
- moderate/low exercise during recovery
- Facilitates recovery
What does steady-state exercise during recovery do?
- Re-synthesis of high-energy phosphates
- replenish O2 in blood
- Replenish bodily fluids
- replenish muscle myoglobin
- small energy cost to elevate circulation/ventilation
Why is passive procedure important during recovery?
- additional elevate total metabolism, delay recovery
What do most individuals do when left to their own choice regarding steady-state exercise?
- Select optimal recovery intensity
What does performing aerobic exercise in recovery do to lactate?
- Accelerates blood lactate removal
Why does performing aerobic exercise in recovery accelerate blood lactate removal?
Increased
- blood perfusion through the liver, heart, and ventilatory muscles
- blood flow through skeletal muscles in active recovery
Describe Intermittent Interval Physical Activity
- Supramaximal exercise to overload specific energy transfer system
- Rapid recovery in interval
What can you do in interval training to overload a specific energy-transfer system?
- Manipulate duration of exercise and rest intervals