The power output of rabbit latissimus dorsi muscle was calculated under isotonic conditions and during oscillatory work. Isotonic shortening studies yielded a maximum power output of 120 W . kg-1 at a P/P0 of 0.4 compared to a maximum power output of 32 W . kg-1 obtained using the work loop technique. This difference can largely be explained by comparing actual work loops with those constructed using force velocity (P/V) and isometric data. At low cycle frequencies, work loop power output is quite close to that predicted from P/V and isometric data. However, at higher frequencies other dynamic muscle properties appear to exert a more marked effect.