The significance of the muscle strength in the endurance of heavy or light dyna-mic cranking work was studied.
The biphasic characteristics of muscular force exertion by dynamic cranking work were almost the same at different speeds. The cranking speed of 90 rpm which was faster than the optimum speed for moderate cranking enabled a longer endurance time at submaximal load of 30 mkg/sec or more. At the dynamically possible maximum load limit the dynamic torque reached at any speed level 80-90% of the isometric max-imum strength.
If the endurance time was expressed as a function of the average effective torque per cycle in percentage of maximum isometric strength, it proved to be variable, being shortened by isometric training and lengthened again by succeeding dynamic training. Pulse rate increase for light cranking became smaller only after dynamic training.
The endurance time for moderate load was concluded to be only in part concerned with muscle strength and is for the most part a function of other factors as blood supply and oxygen utilization, while the maximum dynamic load limit and the endur-ance time for submaximal load was primarily related to the isometric strength.