Continuous stimulation of motor neurons by the tetanus toxin generates maximum muscle tension given time. This is similar to the normal response known as , where greater muscle tension is generated by activating more motor units to accommodate a heavy external force.

Motor Unit Recruitment

Explanation:

Motor unit recruitment may be defined as "the successive activation of the same and additional motor units with increasing strength of voluntary muscle contraction. it involves where greater muscle tension is generated by activating more motor units to accommodate a heavy external force. it always depends on the force/resistance of the activity

With light intensity activity,  slow twitch motor units are recruited. When the load is increased, fast twitch will be recruited with the help of the slow twitch fibers. Therefore slow twitch motor units are always firing no matter what the intensity.