16.423J/HST5l5J Aerospace Biomedical Engineering and Life Support Prof. Newman Prof. Newman Summary Muscle performance Facts/McMahon, Muscles, Reflexes and locomotion, 1984/ 1. In shortening, the relationship between the Force and Velocity is(Hill,s Curve-know this! !) (T+a)(v+b)=(Tota)b Hyperbolic Form muscles shorten more rapidly against light loads than they do against heavy ones muscles which are actively shortening can produce less force than those which contract isometrically 2. There is a discontinuity in the slope of F-V curve at zero velocity 3. Active muscle yields when the load exceeds about 1.8 To (To- Tetanus tension) 4. Hill's observations of the Fenn effect give a linear relation between total rate of energy liberation and tension Fenn=muscle produces a certain extra heat when it shortens a given distance whether shortening velocity is fast or slow 5. Muscle shortening should be based on the relative motion of sliding filaments because A. A-band width stays constant during stretch and shortening B. A-band disappears when myosin is dissolved away C. Actin filaments begin at Z-line, run through I-bands into A-band, but stop before reaching H-zone(muscle at rest length) I-band is entirely actin filaments H-zone is myosin filaments 6. Muscular energy liberation should be based on the splitting of a high-energy phosphate as actomyosin attachments separate16.423J/HST515J Aerospace Biomedical Engineering and Life Support Prof. Newman Prof. Newman Summary Muscle Performance Facts [McMahon, Muscles, Reflexes and Locomotion, 1984] 1. In shortening, the relationship between the Force and Velocity is (Hill's Curve - know this!!): (T+a)(v+b) = (T0+a)b Hyperbolic Form • muscles shorten more rapidly against light loads than they do against heavy ones • muscles which are actively shortening can produce less force than those which contract isometrically. 2. There is a discontinuity in the slope of F-V curve at zero velocity. 3. Active muscle yields when the load exceeds about 1.8 T0 (T0 - Tetanus tension). 4. Hill's observations of the Fenn effect give a linear relation between total rate of energy liberation and tension. Fenn = muscle produces a certain extra heat when it shortens a given distance, whether shortening velocity is fast or slow. 5. Muscle shortening should be based on the relative motion of sliding filaments because: A. A-band width stays constant during stretch and shortening B. A-band disappears when myosin is dissolved away C. Actin filaments begin at Z-line, run through I-bands into A-band, but stop before reaching H-zone (muscle at rest length) I-band is entirely actin filaments H-zone is myosin filaments 6. Muscular energy liberation should be based on the splitting of a high-energy phosphate as actomyosin attachments separate