Abstract
The mechanical properties of frog muscles, especially the elasticity in addition to the viscosity and plasticity, were investigated.
1. The load-extension curve has two phases; namely, the first exponential phase for the lighter loads and the second linear phase obeying Hooke's law for the heavier loads. Under non-physiological conditions, the linearity of the curve tended to increase in most muscles.
2. For the temperature change ranging from 5°C to 40°C, the slopes of the second phase in load-extension curves were not affected in most cases.
3. Modified Young's modulus E was calculated, using sartorius (S), hyoglossus (H), ventricle (V) and oesophagus (O) muscles. The order of the arithmetic means of moduli was as follows: S>H>O>V. Usually the values ranged from 105 to 107 dyne per cm2. When the logarithm of E was taken on the abscissa, the histogram of 88 preparations showed approximately a normal distribution.
4. Based on the calculation of a damped oscillation after quick release, the values of the viscosity coefficient of muscles were obtained, which were the order of 102 (g/cm-sec).
5. Plasticity increases with the time and magnitude of the previous loading, but it is removed completely by electrical stimulation.
