L12;C5 Flashcards
With respect to fatigue, two main factors influence it. What are they?
Decrements—> with continual effort, decrements of fatigue are accompanied by sensation of tiredness
Inability—> inability to maintain required power output to continue muscular work at a given intensity
What is fatigue reversible with?
Rest
What are the four major causes of fatigue?
- Inadequate energy
- Accumulation of metabolic by products and chemical reactions that provide energy transfer
- Failure of muscle contractile mechanism
- Altered neural control of muscle contraction
PCr depletion coincides with what? Why does this occur?
Coincides with fatigue and is used with short term exercise, PCr depletes more quickly and total ATP does
What helps defer PCr depletion? Why?
Pacing, since pi may be caused for fatigue
What is the relationship between glycogen storage and exercise?
As exercise increases, glycogen storage decreases. It will decrease early on. depletion of glycogen has been linked to low exercise
Fibres that are recruited first are most likely to do what first?
Decrease first
Muscle glycogen is insufficient for what kind of exercise?
Prolonged exercise
As muscle glycogen ______ glycogenolysis ______
Decreases, increases
What will muscle glycogen uses vary upon? Give an example?
The type muscle group. For example, at 2 hours at 70% VO2 max gastric uses most glycogen while running.
What limits glycogenolysis?
- NADH production in kreb cycle
- ETC activity
- No glycogen= inhibited substrate oxidation
What are some metabolic by products of fatigue?
- Pi from breakdown fo PCr
- heat retained by body
- lactic acid
- H+ lactic acid—> lactate H+
What happens when heat alters metabolic rate?
- increase in rate of carb utilization
- faster glycogen depletion
- high muscle temp may impaired muscle function
What is the highest temp we can go at 70% max VO2?
11 degrees
Why does muscle PH decrease during a sprint and increase at recovery?
Due to the lactic acid by products, Pi decreases pH and more H+ ions in blood slightly
Lactic acid serves as a source of what?
Fuel
What is lactic acid directly oxidized by?
Type I fibres
What and how is lactic acid converted to?
Lactic acid is converted to glucose via gluconeogenesis (liver)
What are possible causes to neural transmission failure at the junction?
- decrease Ach synthesis and release (hyperactive acetylcholinesterase)
- altered Ach breakdown in synapse
- increase in muscle fibre stimulus threshold
- altered muscle resting membrane potential
What effect does fatigue have on the SR?
Inhibits release of Ca
What is twitch interpolation?
Maximal contraction cant occur without external electrical stimulation
What kind of fatigue is important in the following:
In well training athletes
In repetitive activities
In well training athletes—> peripheral fatigue is important
In repetitive activities—> central fatigue may account for as much as 25% of overall fatigue
When does acute muscle soreness occur? Why?
During or immediately following strenuous/novel exercises.
Accumulation of metabolic by products (H+), tissue edema which leads to acute muscle swelling, and all of it will disappear in a few hours
When does Delayed Onset Muscle Sorness occur?
1-2 days after exercise bouts ranges from stiffness to severe pain
What are the major causes of DOMS? What does muscle damage precipitate?
Eccentric contractions, level run in pain (increased in uphill) and not casues by blood lactate
Muscle damage precipitates hypertrophy
Explain the two concepts of DOMS and inflammation?
Connection with inflammation and soreness
Substances released inflammation
Explain the concepts of connections with inflammation and soreness with respect to DOMS
- WBC defends body against foreign materials and pathologies
- WBC increase with soreness
Explain the concept of substances released inflammation with respect to DOMS
- damaged muscle cells attract neutrophils
- neutrophils release. Attracting chemicals and radicals
- released substances stimulate pain nerves
What are the five sequences of events in DOMS?
- High tension in muscle leads to structural damage to membrane and cell
- membrane damage disrupts Ca homeostasis and inhibits metabolic function of muscle. Inhibits cellular respiration and activates enzymes that degrade the Z disk
- After time, neutrophils will increase
- Products of macrophage activity—> intracellular contents accumulate such as histamines, Kinins, K+, these stimulates pain in free nerve endings and worsen with eccentrics
- fluids and electrolytes shift into area creating edema
Loss of strength is due to three factors in DOMs name them
- Physical disruption of muscle
- Failure in excitation (contractile coupling) * most important
- Loss of contractile protein
What are three ways to minimize DOMs?
- Minimize eccentric work early in training
- Start with low intensity and gradually increase
- Start with high intensity and exhaustive training
What is the repeated bout effect?
This is where the muscle damage responds to only first bout. A single bout can influence individual performance in future.
What are the two types of cramps? Explain them
Exercise Associated Muscle Cramps (EAMC)
- occurs immediately after exercise
- fatigue causes altered neuromuscular control and results in excitation of muscle spindles and inhibition of Golgi tendons. Reversed by stretching.
Heat Cramps
- associated with large sweat and electrolyte losses
- treatment is high NA solutions and ice plus massage
