Skeletal muscle 3; Physiology Flashcards
What is isometric contraction?
No external shortening.
What is isotonic contraction?
- Contraction with movement
- Mismatch between tension generated by muscles and load.
- Isotonic can be; Eccentric or concentric
What is isotonic concentric contraction?
Muscle length decreases against an opposing load.
What is isotonic eccentric contraction?
Muscle length increases as it resists a load
i.e climbing down mountains
What is associated with eccentric contraction?
DOMS are associated with eccentric contraction
What is the force length relationship?
Total force = passive and active
increased length increases the passive force and decreases active.
X axis = Length
Y axis = Force
What is the active force length relationship?
Theres an optimal resting length for the active force length relationship. Increased resting length or decreased lowers the maximal tension.
Whats the force velocity relationship?
- As the load opposing the contraction is increased the velocity of shortening should decrease.
- Constant load = constant velocity (isotonic)
- Power depends on muscle velocity.
When is the contraction most efficient?
- Contraction is most efficient at 1/3 max rate of shortening.
- In humans efficiency ~20-25%
How rapid is ATP production in muscle cells?
- No other cells can produce ATP as fast
- 20-100 fold difference between rest and activity.
What are the sources of ATP?
- CP (10s)
- Glycolysis (1min)
- Aerobic (oxidative p/ph) (3min onwards) - fat or glycogen
What are some sources of muscular weakness?
- Muscular fatigue
- Muscular dystrophy
- Sacropenia
What is muscle fatigue?
Defined as failure to maintain the required or expected power output leading to reduced muscle performance.
Aetiologies not yet clearly established.
Does lactic acid hinder performance?
Nope, its a very good thing.
What are potential sources of muscle fatigue?
- Central fatigue
- Peripheral fatigue.
