... and/or hyperplasia during fall migratory periods compared with breeding and the fall pre-migratory period. Changes in heart mass were driven by the tropical wintering stage, when heart mass was lowest. Mitochondrial content of the heart and pectoralis remained constant across the annual cycle as quantified...

... protocols for 3 weeks on body ( M b ) and muscle ( M pec ) masses, basal metabolic rate (BMR), M sum , MMR, pectoralis mRNA and protein expression for myostatin, and mRNA expression of TLL-1 and TLL-2 (metalloproteinase activators of myostatin) in house sparrows ( Passer domesticus ). Both training...

...-hydroxyacyl Co-A dehydrogenase activities in the pectoralis were generally higher for LD and cold groups. The cold-induced changes in Ṁ sum and heart mass parallel winter changes for small birds, but the larger M b and higher catabolic enzyme activities in LD birds suggest photoperiod-induced changes...

.... Although recent studies have begun to explore how pectoralis (the primary downstroke muscle) neuromuscular activation and wingbeat kinematics are linked in hummingbirds, it is unclear whether different species modulate these features in similar ways, or consistently in response to distinct flight...

... of their remarkable flight muscles. We hypothesized that hummingbird pectoralis fibers generate relatively low force when activated in a tradeoff for high shortening speeds associated with the characteristic high wingbeat frequencies that are required for sustained hovering. Our objective was to measure maximal force...

... biomechanical analogs for incremental adaptive stages in the evolutionary origin of flight. A primary assumption of the hypothesis is that work and power requirements from the primary downstroke muscle, the pectoralis, incrementally increase from shallow- to steep-angled terrestrial locomotion, and between...

... of pectoralis muscle fibres under simulated in vivo strain and activity patterns. Aerodynamic power was calculated using different ranges of values for the coefficients in the equations: induced power factor ( k 1.0–1.4), the profile ( C D,pro 0.01–0.03) and parasite drag ( C D,par 0.05–0.195) coefficients. We...

... ventralis cervicis, m. pectoralis superficialis transversus, the anterior portion of the m. pectoralis profundus, and m. rhomboideus thoracis. Locomotor forces were modified as the dogs trotted at constant speed on a motorized treadmill by (1) adding mass to the trunk, (2)inclining the treadmill so...

...Arya Soman; Tyson L. Hedrick; Andrew A. Biewener SUMMARY Regional fascicle strains were recorded in vivo from the pectoralis of carneau pigeons using sonomicrometry during level slow flight,together with regional electromyography (EMG) and deltopectoral crest (DPC)strain measurements of whole...

... the upstroke. The tip reversal is unusual for birds with rounded wings; it may offer an aerodynamic advantage during rapid acceleration. Flight anatomy generally scaled geometrically, except for average wing chord and wing area, which increased more than expected as body mass ( m ) increased. Pectoralis strain...

...Andrew A. Biewener; William R. Corning; Bret W. Tobalske ABSTRACT For the first time, we report in vivo measurements of pectoralis muscle length change obtained using sonomicrometry combined with measurements of its force development via deltopectoral crest strain recordings of a bird in free...

...Kenneth P. Dial; Andrew A. Biewener ABSTRACT In vivo measurements of pectoralis muscle force during different modes of free flight (takeoff, level flapping, landing, vertical ascending and near vertical descending flight) were obtained using a strain gauge attached to the dorsal surface...

...Andrew A. Biewener; Kenneth P. Dial; G. E. Goslow, Jr ABSTRACT Force recordings of the pectoralis muscle of European starlings have been made in vivo during level flight in a wind tunnel, based on bone strain recordings at the muscle’s attachment site on the humerus (deltopectoral crest...