The force‐velocity relation of rat fast‐ and slow‐twitch muscles examined at different temperatures.

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Abstract
The steady‐state force‐velocity relation was examined at temperatures between 35 and 10 degrees C in rat fast‐twitch (extensor digitorum longus, e.d.l.) and slow‐twitch (soleus) muscle preparations in vitro, with direct stimulation, and employing the isotonic release technique. The curvature of the force‐velocity relation increased with cooling in both muscles; the increase was more pronounced below 25 degrees C. The maximum shortening velocity of e.d.l. muscle decreased with a Q10 (temperature coefficient) of 1.8 in cooling from 35 to 25 degrees C; it decreased with a Q10 of 2.4 in cooling below 20 degrees C. The shortening velocity of slow muscle was more temperature sensitive. The Q10 values for soleus muscle were 2.0 at 35‐25 degrees C and 3.5 below 20 degrees C. The maximum rate of isometric tetanic tension rise had a temperature sensitivity similar to the maximum velocity of shortening in each muscle type.