Final Review Flashcards
Provide an example of what is meant by studying acute responses to a single bout of
exercise.
- instantaneous
- what immediately happens when you begin your work out
- ex. increased cardiac output
- ex. decreased blood flow to visceral organs
Describe what is meant by studying chronic adaptations to exercise training.
- long term effects
- ex. muscular walls in the heart enlarge
- ex. increased respiratory capacity
- ex. improved body composition
What factors must you consider when designing a research study to ensure that you get accurate and reproducible results?
- feasibility
- easily reproducible data collection technique
- specific procedure
- clear population
- budget friendly
- manpower availability
Define the term ergometer
- an apparatus that measures work or energy expended during a period of physical exercise .
Explain the function of an ergometer.
.- evaluate the fitness level of the athlete
- measuring work done by exercising
Advantages of using cycle ergometers for exercise testing in clinical and research settings:
- portable
- less expensive
- minimal upper body movement (easier to measure HR and BP)
- more applicable for measuring cycling performance
- occupies less space
Disadvantages of using cycle ergometers for exercise testing in clinical and research settings:
- people may not be accustomed to cycling (premature fatigue, fail to reach true max cardio output, 10-15% underestimation of VO2 max)
- BP slightly higher than treadmill tests (due to longer muscle contractions)
- Accuracy is based on prediction of MHR
- equipment must be well maintained/calibrated
Advantages of using treadmills for exercise testing in clinical and research settings:
- higher cardiovascular responses
- exercise is controlled by observer (speed), yields more reproducible data
- breathing is easier
Disadvantages of using treadmills for exercise testing in clinical and research settings:
- need space
- need money for treadmill
- upper body movement
- may not be an option if you are obese or have musculoskeletal issues or injuries
- needs maintenance
- can be loud
Explain the placebo effect.
- a beneficial effect
- produced by a placebo drug or treatment, that cannot be attributed to the properties of the placebo itself
- due to the patient’s belief in the treatment
Describe 2 research design methods of controlling for placebo effects.
- blinded trials: subjects do not know whether or not they are receiving real or placebo treatment
- having a natural history group: receive no treatment
Describe additional factors, other than placebo effect, that can introduce unwanted
variation into research results and thus need to be controlled.
- random error (chance)
- systematic error (bias)
- measurement error (reliability and validity)
- misclassification (information bias)
- sampling error
- observer and instrument variation
- absent or inappropriate reference standard
- limited amount of evidence
Once an action potential reaches the axon terminals of an ______, it is ready to
trigger a muscle contraction
α-motor neuron
Describe all the steps of muscle contraction, starting at the axon terminals and ending with muscle relaxation.
- AP starts in brain
- AP arrives at axon terminal, releases ACh
- ACh crosses synapse, binds to ACh receptors on plasmalemma
- AP travels down plasmalemma, T-tubules
- triggers Ca 2+ release from SR
- Ca 2+ enables actin-myosin contraction
- AP ends, electrical stimulation of SR stops
- Ca2+ pumped back into SR
- without Ca2+, trooping and tropomyosin return to resting conformation
Describe the key structural and functional differences in the three major muscle fiber
types.
.- Type I peak tension in 110 ms 50% of fibres Slower myosin ATPase = slower contraction cycling Smaller neuron < fibres - Type II Peak tension in 50 ms (fast twitch). 25% of fibres each. Fast myosin ATPase = fast contraction cycling More highly developed SR Faster Ca2+ release Larger neuron >300 fibres
- different types of myosin
How do the differences in the 3 major muscle fibre types result in different exercise capabilities?
Type I - high aerobic endurance - low intensity aerobic exercise, daily activities Type IIa - more force, faster fatigue than type I - short, high intensity endurance events Type IIx - seldom used for everyday activities - short, explosive sprints
Describe the different methods that muscles use to increase the force of contraction.
- more force production: more or larger motor units (Type II)
- length-tension relationship (optimal sarcomere length)
- speed-force relationship (concentric: maximal force development decreases at higher speeds) (eccentric: maximal force development increases at higher speeds)
How much energy does a gram of each 3 major energy substrates yield?
- carb: 4.1 kcal/g
- fat: 9.4 kcal/g
- protein: 4.1 kcal/g
How are each 3 major energy substrates stored?
Carbs
- all converted to glucose
- 2500 kcal stored in body
- extra glucose stored as glycogen in liver, muscles
Fat
- +70,000 kcal stored in body
- must be broken down into free fatty acids and glycerol
Protein
- must be converted into glucose
- can also convert into FFAs (energy storage)
When are each 3 major energy substrates preferentially used?
- carb: immediate
- fat: prolonged, less intense exercise
- protein: during starvation
Site of production for each of 3 metabolic pathways the body uses to generate ATP:
ATP-PCR system ? Glycolytic System - all steps occur in cytoplasm Oxidative System - occurs in mitochondria
ATP yield for each of 3 metabolic pathways the body uses to generate ATP:
ATP-PCR system - 1 mol ATP/1 mol PCr Glycolytic system - 2-3 mol ATP/1 mol substrate Oxidative System - depends on substrate - 32-33 ATP/1 glucose - 100+ ATP/1 FFA
Duration for each of 3 metabolic pathways the body uses to generate ATP:
ATP-PCR system - 3 to 15 s Glycolytic System - 15s to 2 min Oxidative System - steady supply for hours
Oxygen or substrate requirement for each of 3 metabolic pathways the body uses to generate ATP:
ATP-PCR system - phosphocreatine (PCr): ATP recycling Glycolytic System - uses glucose or glycogen Oxidative System - glucose - FFA
Corresponding optimal form(s) of exercise for each of 3 metabolic pathways the body uses to generate ATP:
ATP-PCr system - 3-15 s maximal exercise Glycolytic System - allows muscle to contract when O2 limited - short term high intensity exercise - 2 min maximal exercise Oxidative System - long endurance
Describe the three ways in which lactate can be used as a fuel by the exercising muscle.
- lactate produced in cytoplasm can be taken up by the mitochondria of the same muscle fibre and oxidized
- lactate can be transported via MCP transporters to another cell and oxidized there (lactate shuttle)
- lactate can recirculate back to the liver, reconverted to pyruvate and then to glucose through gluconeogenesis
Outline the sequence of events that is thought to contribute to the development of
DOMS.
- high tension in muscle –> structural damage to muscle, cell membrane
- membrane damage disturbs Ca2+ homeostasis in injured fibre (inhibits cellular respiration, activates enzymes that degrade Z disks)
- after few hours, circulating neutrophils
- products of macrophage activity, intracellular contents accumulate (histamine, kinins, K+, stimulate pain in free nerve endings)
- fluid and electrolytes shift into the area creating edema
What exercise practices promote the development of DOMS?
- eccentric contracions
What exercise
practices help avoid the development of DOMS?
.- minimize eccentric work early in training
- start with low intensity and gradually increase
- start with high intensity exhaustive training (soreness bad at first, much less later on)
Theory behind direct calorimetry:
- substrate metabolism efficiency
- 40% of substrate energy: ATP
- 60% of substrate energy: heat
- heat production increases with energy production
