Timing of anticipatory responses following an isometric contraction

The effects on timing of anticipation following an isometric contraction were investigated. Using a Bassin timer, 35 subjects performed 10 trials for each of 4 forewarning periods at 3 stimulus speeds resulting in 120 trials for the control condition. An additional 120 trials were performed by all subjects following an isometric contraction for each trial. Over all trials, average responses indicated early anticipation of the timing target. The shortest forewarning period and slowest speed of stimulus produced the earliest responses and the longest forewarning period and fastest speed of stimulus produced responses closest to temporal coincidence. Subjects responded faster after the isometric contraction. Significant differences were observed for the main effects of forewarning period and speed of the stimulus. A significant interaction resulted for condition by forewarning periods. The postcontraction condition produced a significantly earlier average response than the control condition for all but the shortest forewarning period. The findings supported the concept that the time needed to respond during postcontraction effects is reduced. With prior contraction, anticipatory timing gradually diminished over time following the contraction.