Fig. 1.

Average stretch reflex amplitudes of one subject. The order of trials was random but shown in an order to illustrate the difference between the rest trials and others. R indicates rest; TC indicates teeth clench, which consists of biting on an individualized mouth guard with maximal force; HP indicates clenched hand pull, which consists of trying to pull the hands apart against interlocked fingers; and JM indicates the Jendrassik maneuver, which consists of both clenched hand pull and teeth clench.