ISOMETRIC AND ISOTONIC MUSCLE PROPERTIES AS DETERMINANTS OF WORK LOOPPOWER OUTPUT

The power output of rabbit latissimus dorsi muscle was calculated unde r isotonic conditions and during oscillatory work. Isotonic shortening studies yielded a maximum power output of 120 W . kg(-1) at a P/P-0 o f 0.4 compared to a maximum power output of 32 W . kg(-1) obtained usi ng the work loop technique. This difference can largely be explained b y comparing actual work loops with those constructed using force veloc ity (P/V) and isometric data. At low cycle frequencies, work loop powe r 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.