energy demands of muscles and types of muscle fibers

short term (10 secs)

uses ATP-CP (creatine phosphate) to generate more energy

glycolysis (10-40 secs)

anaerobic (w/o O₂) respiration of glucose yields 2 ATP → lactic acid; accumulation of lactic acid causes fatigue

krebs (several mins to hrs)

aerobic respiration of glucose yields large amounts of ATP → constant supply of O₂

red

(slow oxidative type 1), lots of myoglobin, thin fibers, less force, non-fatigable, slow-acting ATPase

EX. POSTURAL MUSCLES

pink

(fast oxidative type 2), little myoglobin, slightly thick, more force, slightly fatigable, fast ATPase

EX. WALKING MUSCLES

white

(fast glycolytic type 3), no myoglobin, thick, lots of force, fatigable, fast ATPase

EX. SPRINT, WEIGHTLIFTING