BIOLOGY 3XL3 Chapter 4: Muscle III - Movement
4 Feb 2017
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Adaptation of muscle for diverse activities jumping. For high power output: work at plateau of sarcomere length-tension curve (max. force, muscle should shorten at a rate where maximum power generated, should become maximally activated (every fiber in active state) before shortening begins. Frogs pause before the jump where muscle generates the tension: allows enough time for all muscles to become maximally stimulated and enough ca accumulation inside each cell, crouch to extended position in 50-100ms. Force exerted by muscle around a join creates a moment. The magnitude of the moment dependent on the moment arm (d) Hip joint rotates around the point where the femur attaches. Muscle contraction acts through a moment arm to pull on the pelvis. Moment arm = distance separating a fixed fulcrum from a point which force is produced. Length of moment arm determines average and how much the muscle must shorten to change the angle of the hip join.
