8392 Lecture Notes - Lecture 15: Muscle Fatigue, Pyruvic Acid, Soleus Muscle
20 Jun 2018
School
Department
Course
Professor
LECTURE 15 – Fatigue: Body to mind complexity
Why do they fatigue?
- Bens definition
oReduction’in the ability to
Generate force of power with a muscle and/or
Control movement in a skilled manner and/or
Make informed judgement
oThat effects performance, below what a given individual is known to be capable of
- What causes fatigue?
oRan out of ATP
oLactic acid
oOxygen debt
oWasn’t strong enough mentally
oToo hot
oDehydrated
oFeel sluggish
oSickness
oOut of fuel
Peripheral fatigue
- Muscle site
- Subcompartments
- More systemic (but still sub-spinal eg O2 supply)
- ATP supply effected by
oSubstrate availability
CHO, O2
oReaction rates
Inhibition, catalysts, substrate levels
Lactic acid and fatigue
- Lactate and hydrogen ion tend to quickly dissociate
- If pyruvate couldn’t turn into lactic acid?
oStop reaction
find more resources at oneclass.com
find more resources at oneclass.com
oIf turns into lactic acid – process continues
Prevents fatigue
- Acidity is necessary for processes
oToo little or much can slow down processes
- Not related to fatigue – the lactate paradox?
- High altitude
oLactate levels decrease
Doesn’t cause fatigue
Lactic acid is not all bad
- Isolated rat soleus muscle
oIncubated in potassium
oStimulate every 10 mins to see force production
oFatigue results
oThen add lactic acid to the incubation solution
oAllowed muscle to regenerate force, allowing contraction
- Lactic acid revived muscle
ATP – we run out of energy?
- Rigor mortis
- Myosin head detaches from actin
- Run out of atp = stiff
oOnly happens after death
- Always atp around
- Can have low levels of ATP
Isolated muscle fatigue
- Rapid dec in force if asked to contract muscle
- No outside electric stimulus – they need to do it themselves
- Dec IEMG – brain is asking less of muscles over time
oBrain at fault?
find more resources at oneclass.com
find more resources at oneclass.com
-
- Lift 3kg weight with fingers
oRepeatedly
oMore and more = fatigue as expected
oDid it the next day after lecturing
- Fingers fatigued quicker
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 15 fatigue: body to mind complexity. Generate force of power with a muscle and/or. Make informed judgement: that effects performance, below what a given individual is known to be capable of. What causes fatigue: ran out of atp, lactic acid, oxygen debt, wasn"t strong enough mentally, too hot, dehydrated, feel sluggish, sickness, out of fuel. More systemic (but still sub-spinal eg o2 supply) Lactate and hydrogen ion tend to quickly dissociate. If pyruvate couldn"t turn into lactic acid: stop reaction, if turns into lactic acid process continues. Acidity is necessary for processes: too little or much can slow down processes. Isolated rat soleus muscle: incubated in potassium, stimulate every 10 mins to see force production, fatigue results, then add lactic acid to the incubation solution, allowed muscle to regenerate force, allowing contraction. Run out of atp = stiff: only happens after death. Rapid dec in force if asked to contract muscle.
