Frequency plots of complex moduli . values during standard activation at are plotted as (a) dynamic modulus versus frequency, (b) phase shift versus frequency, and (c) viscous modulus versus elastic modulus (Nyquist plot) with the frequency as a variable. Muscle models from three different Tms are compared. The averaged data of 15 (nfTm), 17 , and 18 preparations are shown. Frequencies tested were 0.13, 0.25, 0.35, 0.5, 0.7, 1, 1.4, 2, 3.1, 5, 7, 11, 17, 25, 35, 50, 70, and 100 Hz (clockwise in (c)). The data are fitted to (3). The continuous curves represent represent calculated values from (3) with best-fit parameters. The units of all moduli are , phase shift is expressed as degree, and frequency in Hz. The resting modulus was not subtracted.