Lecture 2 Flashcards
Steady State Aerobic Exercise System contributions at different intensities
Energy sources at constant intensity submaximal aerobic exercise onset
Immediate Energy store for muscular contraction: The CP-ATP system
“stored” ATP in cell used for:
rapid transitions in energy expenditure
Immediate Energy store for muscular contraction: The CP-ATP system
Engaged at:
- start of exercise or abrupt changes in effort
Immediate Energy store for muscular contraction: The CP-ATP system
Limited store:
6-8 seconds of all out-work
Immediate Energy store for muscular contraction: The CP-ATP system
Rapid resynthesis of this “storage” pool of ATP is accomplished via
hydrolysis of creatine phosphate (CP)
Immediate Energy store for muscular contraction: The CP-ATP system
Transfer rate is __X that of aerobic pathways
4-8X
Energy demand equation
-catalyzed by
CP + ADP → ATP + C
- catalyzed by creatine kinase*
- ATP levels will decrease in active muscle with critical depletion of CP stores*
Recovery (rapid) equation
C + ATP → ADP + CP
From what is recovery ATP derived?
Catabolism of foodstuffs via glycolysis or aerobic metabolism
Testing Capacity of Immediate Energy System
Performance
Power tests:
- stair climbing, jumping
- sprint (40yd sprint for football)
- power tests used for specific performance gains with training (within the same subject) and for training itself
Testing Capacity of Immediate Energy System
Assumptions/Design
- All ATP is generated via CP-ATP system at peak power output
- Enough CP/ATP stored to support maximum performance
Testing Capacity of Immediate Energy System
Significant limitations
- Test <6 seconds
- link of performance and general CP-ATP capacity hard to assess in field tests
- Performance is skill & motivation dependent
Short term system: glycolysis
Duration:
Additional ATP production from:
>6s
Additional ATP production from glycolysis and aerobic mechanisms
Short term system: glycolysis
Proportion provided from anaerobic/aerobic sources depends on
intensity and duration of exercise
Short-term Energy system tests
Performance for anaerobic power
- Wingate test (cycle ergometer or arm crank)
- Repetitive testing (running, weightlifting)
Short term system: glycolysis
Assumptions/design criteria
- Substantial activation of anaerobic systems during maximal exercise up to 3 min
- Must control for task complexity and muscle group specificity
Wingate test
30 sec. all out effort with a specific resistance chosen based on body mass (arm crank or cycle ergometer)
Wingate test outcome measures
**Peak power output vs average power output
- Peak power output: assumes CP-ATPase capacity is tested
- Average power output: assumes glycolytic capacity tested
Resultant “power scores” compared to age and gender normative values
Long-term energy: Aerobic Metabolism
Provides majority of ATP if exercise is:
>2-5mins
Long-term energy: Aerobic Metabolism
Oxygen needed to drive ATP production via
- increased pulmonary O2 uptake and
- Delivery to muscle via CV system
Rest-to-Exercise Transition in Oxygen Uptake
- The rise in oxygen uptake (VO2) “lags” begin energy expenditure at the start of exercise.
- Oxygen defecit during transitional stage represents energy provided by anaerobic metabolism
- After several mins (3-4) of constant intensity of submax exercise, VO2 reaches steady state
- In submax exercise, majority of energy dervied from aerobic processes
- Steady state, submax exercise = Balance between energy demand (expenditure in kcala) and oxygen uptake
- **THUS → VO2 (O2 uptake) = good index of energy expenditure
Recovery from exercise
- At cessation of exercise, VO2 does not immediately return to resting levels
- Excess postexercise oxygen consumption (EPOC) = difference between predicted resting VO2 and actual VO2 measured during recovery
- Rate of recovery to basal levels will depend on the intensity and duration of exercise: higher intensity or longer duration increase EPOC
Think of EPOC as:
extra energy necessary to return the body to the pre-exercise state
Two components to the exponential fall in VO2
- Fast (maximal in first 30s)
- Slow (could take 1-to up to 24 hours)
- particularly important after exercise of moderate-heavy intensity
Causes of fast EPOC
- Resynthesize CP and ATP stores in muscle
- Replace O2 blood stores in blood, body fluids, and myoglobin
Causes of slow EPOC
- Lactate removal (oxidation and gluconeogenesis)
- Elevated core temp (increases metabolism)
- Elevated horomoes (increases metabolism affecting heart, liver, muscle function)
- O2 demands of heart, respiratory muscles, etc. during recovery
Number of calories burned during EPOC
- Interindividual EPOC variaation
- Typical exercise (walking, jogging - 30 min @ mod intensity)
- EPOC < 50kcal
- Longer (> 60 min) or higher intensity (>70% VO2 max)
- EPOC from 70-160kcal
ppl on moderate exercise programs looking to lose weight should concentrate on increasing frequency or duration of the exercise itself (rather than counting on EPOC) to meanfully increase caloric expenditure in pursuit of their goal
Maximal oxygen comsumption (VO2 max)
Physiologic definition
Maximal capacity to transport and utilize O2
Maximal oxygen comsumption (VO2 max)
Operational definition
VO2 at which O2 uptake no longer increases with an increase in workload
Maximal oxygen comsumption (VO2 max)
Peak aerobic power or peak oxygen uptake (VO2 peak)
- Term used when its not clear that exercise elicited “true” physiologic VO2 max
- VO2 plateau in VO2 not demonstrated (common in exercise testing)
VO2max is a fundamental measurement in:
in exercise physiology
an important component of endurance performance
VO2 max reflects (2 things)
- capacity for aerobic energy transfer
- Function and integration of physiological systems involving uptake, delivery, and utilization of oxygen
VO2 max diagram (relative vs. absolute)
Oxygen transport system
- pulmonary ventilation
- Transfers O2 to blood
- Cardiac function
- Blood flow to active muscles (organs)
- Transfer O2 to muscle
- Metabolic function of muscle
Absolute workload expressed as
- ml/min/kg
- l/min
- Watts, mph, kgm-min,
Relative workload expressed as
- Relative (%) to a standard (usually that person’s maximum HR or maximum VO2)
VO2 reserve
VO2 max - resting VO2
Expressions of intensity as relative workloads allows for comparisons of exercise responses between different persons because:
- individuals should be working at the same relative physiologic stress even if the absolute workloads are different
At the SAME absolute workload, subject A is working at a lower % of Maximum Capacity compared to subject B
At the same relative workload, Subject A is working at a higher absolute workload than subject B