Fig. 3. Percentage of the muscle's length change in each twitch (i.e. strain) in flying and singing muscle as a function of contraction frequency. The vertical line represents the range of strain values found for tailshaker muscle. Data are from Biewener et al. (1998), Ellington (1991), Gilmour and Ellington (1993), Girgenrath and Marsh (1999), Josephson and Stevenson (1991) and Moon et al. (2002).