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+# 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 
+
+