Week 9 - Effects of aerobic and anaerobic training Flashcards
What are the two key factors to consider when training/performing?
source of energy (ATP-PC system, anaerobic glycolysis, aerobic metabolism) and fibres used for force production (type I, IIa, IIx)
Describe the “Overload” principle of training.
Training effect occurs when a physiological system is exercised at a level beyond which it is normally accustomed
Describe the “Specificity” principles of training.
Training effect is specific to:
* Muscle fibers recruited during exercise.
* Energy system involved (aerobic versus anaerobic).
* Velocity of contraction.
* Type of contraction (eccentric, concentric, isometric).
Describe the “Reversibility” principle of training.
Gains are lost when training ceases.
What are the 3 key principles of training?
1) Overload
2) Specificity
3) Reversibility
What is the main goal of endurance training? What would this training look like?
to increase VO2max
- Large muscles groups trained with dynamic activity.
- 20-60mins, 3x per week, >50% V02max.
What is the average increase in V02max with endurance training? How does this differ with variations in initial V02max?
15-20%
- Smaller increased in individual with high initial V02max. (2-3% - they may require higher exercise training intensities to obtain improvements - >70% V02max)
- Up to 50% in those with low initial V02max.
How much of our V02max is determined by heritability (genetics) in sedentary adults?
50% of V02max in sedentary adults
As well as V02max, what does genetics also play a key role in?
determining the training response - large variations in training adaptations reveal that heritability of training adaptations is approximately 47%.
What is v02max defined by?
Fick equation
V02max = maximal cardiac output X a-vO2 difference
What are differences in VO2max between individuals primarily due to?
differences in SV max - this then influences maximal cardiac output and VO2max
In terms of short duration training (approx. 4 months) what is the dominant factor for exercise-induced improvements in V02max?
increase in SV dominant factor in increasing V02max
In terms of longer duration training (approx. 28 months) what is the dominant factor for exercise-induced improvements in V02max?
Both SV and a-vO2 increase to improve VO2max
How does training increase maximal stroke volume?
Increase preload (End Diastolic Volume)
- Increase plasma volume (days)
- Increase venous return (days)
- Increase ventricular volume (months to years)
Decreased total peripheral resistance (“afterload”)
- Decrease arterial constriction (decrease SNA)
- Increased maximal muscle blood flow with no change in mean arterial pressure
Increased contractility
- Greater force produced with each contraction
Eccentric hypertrophy
chamber size and wall thickness increases in the heart
What happens to cardiac output after training?
Cardiac output can be achieved with fewer beats per min. This is because HR is lower due to an increase in stroke volume.
What does lower resting HR after training lead to?
- Vagal tone increased
- Also allow greater filling time (EDV)
Why may maximum HR fall slightly in the highly endurance trained?
Intrinsic firing rate of SA node decreased?
Following endurance training what happens to post-exercise HR recovery?
its faster
What are the factors responsible for the training-induced increased in arteriovenous O2 difference?
- Muscle blood flow increase
- Decreased SNS vasoconstriction
- Increased diameter and compliance of arteries - Improved ability of muscle fibers to extract and utilize O2 from the blood.
- Increased capillary density: slower blood flow through muscle.
- Increased mitochondrial number/volume.
How does exercise training increase total capacity of vascular bed in the muscle?
i. large conduit artery expansion
ii. increased numbers of resistance vessels
What happens to the transit time of RBCs as a result of training?
- Transit time is increased
overall because with bigger
capillary network, RBCs take
longer to pass through
Endurance training increases the volume of both … and … (80% of total) mitochondria in muscle fibers. What does this result in?
Subsarcolemmal and intermyofibrillar.
This results in improved oxidative capacity and ability to utilize fat as fuel.
During submaximal exercise, explain what happens to blood flow in trained muscles?
Blood flow in trained muscles is LOWER because the A-V difference is greater (better oxygen extraction)
During maximal exercise, explain what happens to blood flow in trained muscles?
blood flow in trained muscle is higher and the A-V difference is greater.
What does training-induced improvements in homeostatic processes result in?
- A more rapid transition from rest to steady state
- A reduced reliance on limited liver and muscle glycogen stores
- Numerous CV and thermoregulatory adaptations that assist in maintaining homeostasis.
What are the 5 adaptations in muscle fibers in response to endurance exercise training that assists the maintenance of homeostasis?
- Shift in muscle fiber type (fast-to-slow) and increased number of capillaries.
- Increased mitochondrial volume and mitochondrial turnover in skeletal muscle
- Training-induced changes in fuel utilization.
- Increased antioxidant capacity.
- Improved acid-base regulation.
Explain how endurance training promotes a fast-to-slow shift in muscle fiber muscle type.
Reduction in fast fibers and increase in number of slow fibers.
Incr. in slow myosin isoform, which have lower myosin ATPase activity but better efficiency (i.e. perform more work with less ATP utilization).
What is the magnitude of fiber type change determined by?
Duration of training
Type of training
Genetics
What is the effect of an increased number of capillaries surrounding muscle fibers?
- Enhanced diffusion of oxygen.
- Improved removal of wastes.
Mitophagy
breakdown of damaged mitochondria
What is the significance of an increased mitochondrial volume and turnover in the muscle in response to endurance training?
Greater capacity for oxidative phosphorylation.
Decreases cytosolic [ADP] due to increased ADP transporters in mitochondrial membrane, which results in:
* Faster ADP uptake into mitochondria and lower cytosolic ADP
* Less lactate and H+
formation.
* Less PC depletion.
However, during submaximal exercise, the steady-state VO2
is not influenced by endurance training… (i.e. volume of work is the same, just more efficient)
What are the endurance training-induced changes in fuel utilization?
1) Increased utilization of fat and sparing of plasma glucose and muscle glycogen.
2) Improve plasma FFA transport and oxidation
What are the 3 ways that endurance training adaptations improve plasma FFA transport and oxidation?
1) Increased transport of FFA into the muscle (i.e. from plasma): due to increase capillary density and fatty acid binding protein.
2) Transport of FFA from the cytoplasm to the mitochondria.
* Higher levels of carnitine palmitoyl transferase and Fatty Acid Translocase.
3) Mitochondrial oxidation of FFA.
* Increased enzymes of β-oxidation.
* Increased rate of acetyl-CoA formation.
* High citrate level (as result of incr. β-oxidation) inhibits PFK and glycolysis.
How does endurance training improve the antioxidant capacity of muscle?
Training increased endogenous antioxidant enzymes which:
- Improves the fibers ability to remove radicals.
- Protects against exercise-induced oxidative damage and muscle fatigue.
How does endurance exercise training improve acid-base balance during exercise?
Increased mitochondrial number.
* Less carbohydrate utilization + more FFA oxidation = less pyruvate formed.
Increased mitochondrial uptake of pyruvate and NADH
* Less NADH available for lactic acid formation.
Increased H4 form of LDH: decreases lactate formation
Describe the molecular bases of exercise training adaptation.
Muscle contraction activates primary and secondary messengers.
Results in expression of genes and synthesis of new proteins.
Examples of primary signals involved in exercise-induced apaptations.
Mechanical stretch
Calcium
AMP/ATP increased
Free radicals
Describe the most important secondary messenger in skeletal muscle.
PGC-1a
- Master regulator of mitochondrial biogenesis; increased capillarization (angiongesis), and synthesis of antioxidant enzymes
- Activated by AMPK and CaMK
What are training-induced reductions in HR and ventilation due to?
Improved muscle homeostasis during exercise and reduced “feedback” from muscle chemoreceptors to
cardiovascular control center.
Reduced number of motor units recruited.
Endurance training INCREASES OR REDUCES central command outflow during submaximal exercise. What does this result in?
Reduces
Results in a lower HR and ventilatory response during exercise.
e.g. improvements in muscle fiber oxidative capacity means that fewer motor units are required for submaximal work.
What is the effect of detraining?
Rapid decrease in VO2max.
* ↓ approximately 8% within 12 days; ↓ 20% after 84 days.
↓ SV max.
* ↓ Rapid loss of plasma volume.
↓ Maximal a-v O2 difference.
* ↓ ↓ Mitochondria.
* ↓ ↓ Oxidative capacity of muscle.
* ↓ ↓ Type 2a fibers and ↑ type 2x fibers.
What is the initial decrease in V02max due to? What about later decreases?
Initial decrease = decreased SV max
Later decrease = decreased A-V O2max
How many weeks of endurance training does it take for muscle mitochondrial volume to double?
5 weeks
How quickly are mitochondrial adaptations lost with detraining?
- Loss of 50% of training gains within 1 week of detraining.
- Majority of adaptation lost in two weeks.
How many weeks does it take of retraining to regain mitochondrial adaptations?
3-4 weeks of retraining
How does anaerobic training increase performance?
- 4-10 weeks of sprint training can increase peak anaerobic power by 3-28% across individuals.
- Improves muscle buffering capacity by increasing both intracellular buffers and
hydrogen ion transporters. - Hypertrophy of type 2 muscle fibers and elevates enzymes involved in both the ATP-PC system and glycolysis.
- High intensity interval training >30 seconds (at near or above VO2 max) promotes mitochondrial
biogenesis
During the first 4 months of an endurance exercise training program, the initial increase in V02max is primarily due to what?
increases in SV and increases in maximal cardiac output
Endurance training has been shown to reduce the oxygen deficit in subjects performing a bout of submaximal exercise. What is this likely due to?
increases in the number of mitochondria and capillaries
