PHYSIOL 201 Lecture 9: Types of Tension and Fatigue
4 Feb 2019
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Skeletal muscle fiber types: fibers can be classified based on their primary metabolic pathway utilized to produce. Skeletal muscle energy metabolism: muscles have 3 ways to generate atp, glycolysis, oxphos, creatine phosphate, creatine phosphate goes to creatine and phosphate which is added to adp to generate. 3 classifications of skeletal muscle fibers: fast glycolytic (iib, produces the most force/tension because they are bigger. There are more sarcomeres in parallel so the fiber can produce more force: fast oxidative (oxidative-glycolytic) (iia, slow oxidative (i) If you normalize force production to size (cross sectional area), then all skeletal muscle fiber types produce equivalent force. It is not due to significant atp depletion: atp measurements in fatigues muscle fibers show that dangerous atp depletion does not occur. Atp depletion would lead to rigor which is very damaging to muscles: fatigue occurs before atp levels drop too low, and so may be protective. If pi is not released, then no power stroke occurs.
