As shown in FIG. 1 the exercise machine of the preferred embodiments includes a mechanical force input interface 1 designed to interface with a user 5 and allow the user 5 to input force 4 into the exercise machine; a force resistor 2 that functions to resist force input into the mechanical force input interface 1 by the user 5; and a trigger mechanism 3 that functions to cause a sudden change in the resistance provided against the force input 4 by the user 5. The exercise machine of the preferred embodiments is designed to exercise muscles in a way that improves muscle speed, explosiveness, or both.