highschool-senior/anatomy/Muscle_Fatigue.md

Muscle Fatigue

"decrease of a muscle's ability to maintain tension/power over time"

no oxygen -> that makes lactic acid

lactic acid is short term

fatigue - can no longer preform level of activity

often oxygen debt

recover period, failure / rest

preform glycolysis, liver breaks down lactic acid into glucose USING ATP (only works in rest period) cori cycle

muscles have different fiber types - therefore has different fatigue

• type I - slow oxidative
• type IIa - fast oxidative
• type IIx - fast glycotic

all muscles have all fivers, density is the key differentiators

Slow oxidative Muscle Fibers (Type I)

• "slow twitch"
• works in oxygen, and moves slowly
• structural characteristics
  • small muscle diameter
  • more vascularity/high capillary density + high mitochondria density -> aerobic!
• Metabolic characteristics!
  • take three times longer to contract ( slowest of all fibers) -> sustained movement (fatigue resistant)
    • impulse to move is 3 times slower than others
  • contains myoglobin -> stores oxygen (short term)
• function
  • first muscle fibers to be recruited (low power)
  • run marathons (can be used for hour+)
  • anti-gravity + posture muscles
• basically hard to wear out. the marathon muscle

fast oxidative fibers (type IIa)

• structural characteristics
  • humans largest diameter muscle fiber
  • highly vascularizaion + high density density of mitochondria -> aerobic!
  • high density of muscle glycogen / some myoglobin
• Metabolic characteristics
  • can utilize anaerobic respiration
    • glycolysis
    • creatine phosphate to ADP = some ATP
      • can add some extra fatigue resistance to the muscle
  • fast contractility -> moderate fatigue resistance
• function
  • 2nd recruitment order -> moderate power
  • walking/sprinting (longer than one minute, shorter than 30 minutes)

Fast Glycolytic (Type IIx)

• Structural Characteristics
  • intermediate diameter (humans)
  • "white fibers" -> paleish pink
  • very little vascularity , mitochondria -> almost no aerobic respiration
  • high muscle glycogen / little to no myoglobin
• use as much energy as fast as possible
• metabolic characteristics
  • primary anaerobic
    • Glycolysis
    • Creatine phosphate + ADP = some ATP
  • Fastest Contractily -> Lowest fatigue resistance
  • makes some ATP quickly -> uses it much faster
• function
  • 3rd recruitment order -> highest power
  • heavy weight training / burst power (less than 60 sec)

Changes in density

• genetics + enviornmental stress
• hypertrophy vs atrophy
  • changes density of muscles
• endurance exercise (trend to type Ia)
  • angiogenesis (increase amount of blood vessles to the muscles)
  • increase myoglobin + mitochondria
• resistance exercise (trend to type II's)
  • damage leads to increase in mass
    • literally split muscle fibers -> repaired bigger
  • increase in myofibrils )size and number)
  • increase in glysosomes (store glycogen))
  • strengthens Connective Tissue, tendons, and bones

basically as you train, the muscles work on making it easier by handling those

muscle memory: going back to state of athletic state, enviornmental stress