EHS 385 Lecture Notes - Lecture 12: Cachexia, Sarcopenia, Sarcomere
18 Dec 2017
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Chapter 8 lecture 12 oc skeletal muscle iii. Number and types of motor units recruited: more motor units = greater force, fast motor units = greater force. Initial muscle length: ideal length for force generation, increased cross-bridge formation. Nature of neural stimulation of motor units: frequency of stimulation: simple twitch, summation, tetanus. Contractile history of muscle: fatiguing exercise, warm up exercise results in post-activation potentiation . Max force per cross-sectional area: 10-20% higher in fast fibers (2a and 2x) compared to slow (type 1) fibers. Force production related to number of myosin cross-bridges in strong binding state: fast fibers contain more cross-bridges per cross-sectional area. Both diseases and aging can negatively impact muscle function. Aging and muscle loss: sarcopenia, 10% muscle mass lost between age 25-50 years, additional 40% lost between age 50-80 years, also loss of fast fibers and gain in slow fibers, resistance training can delay age-related muscle loss.
