Brief, intense muscular effort produces a long-lasting facilitation
of the motoneuron pool that was originally described in animal studies
(post-tetanic potentiation) and can be demonstrated in human subjects,
as Robert Newton has suggested. Sometimes it is called the aftercontraction
effect (Craske & Craske, Journal of Motor Behavior, 18, 117-145, 1986) but
it is also often called post-contraction. Much of the literature is older
(e.g., Sapirstein, M.R. "A study of after-contraction", Am J Physiology,
119, 549-556, 1957). I conducted an experiment several years ago
(unpublished) and found that a preliminary maximal isometric effort
facilitated peak torque in a subsequent isokinetic contraction. Other
interesting studies include Vandervoort et al (Exp Neurology, 81, 141-152,
1983) and Zigler ("The Neurophysiology of post-contraction" Psych review,
51,315-325, 1944).

Gary Kamen
Department of Physical Therapy
Boston University