Pectoralis muscle force and power output during flight in the starling

摘要: Force recordings of the pectoralis muscle European starlings have been made in vivo during level flight a wind tunnel, based on bone strain at muscle9s attachment site humerus (deltopectoral crest). This represents first direct measurement force activity live animal calibrated recordings. Our measurements confirm earlier electromyographic data and show that begins to develop final one-third upstroke, reaches maximal halfway through downstroke, sustains throughout downstroke. Peak forces generated by speed estimated be 13.7ms −1 averaged 6.4N (28% isometric force), generating mean mass-specific power output 104 W kg . Combining our for with metabolic flying similar yields an overall efficiency 13 %. The length changes muscle, angular displacements humerus, indicate undergoes lengthening--shortening contraction sequence its activation that, addition lift thrust generation, overcoming wing inertia is probably important function this flapping flight.