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Brandy Velten (doctoral student) and Dr. Kenneth Welch (Comparative Physiologist) from the University of Toronto wanted to know whether birds with very different speeds at which they flaps their wings (i.e. wingbeat frequencies) had correspondingly varying types of myosin proteins in their muscles. Their findings were published in the American Journal of Physiology last month.
In their study they compared ruby-throated hummingbirds and zebra finches which reportedly have some of the highest wingbeat frequencies (20-60Hz). As you can imagine, their flight muscles are made up of almost exclusively of muscle fibers that contract very fast (i.e. fast twitch). Whereas a chicken’s breast muscle (i.e. pectoralis) is composed of mostly slow-twitch muscle fibers that are more important in controlling things like posture. Myosin heavy chain (MHC) is very important in regulating the ability for a muscle to contract (for a review of myosin, see the video at the end of this post). The type of MHC varies depending on whether a muscle is mainly slow or fast twitch. It was these variations in the MHC protein that this study explored in the following birds:
In their study they compared ruby-throated hummingbirds and zebra finches which reportedly have some of the highest wingbeat frequencies (20-60Hz). As you can imagine, their flight muscles are made up of almost exclusively of muscle fibers that contract very fast (i.e. fast twitch). Whereas a chicken’s breast muscle (i.e. pectoralis) is composed of mostly slow-twitch muscle fibers that are more important in controlling things like posture. Myosin heavy chain (MHC) is very important in regulating the ability for a muscle to contract (for a review of myosin, see the video at the end of this post). The type of MHC varies depending on whether a muscle is mainly slow or fast twitch. It was these variations in the MHC protein that this study explored in the following birds: