Decreased motor activity of hyperactive children on dextroamphetamine during active gym program

The motor activity of 10 hyperactive boys was measured during eight 1-hour active gym classes. Children received either dextroaomphetamine (0.5 mg/kg) or placebo elixir before each class, in a double-blind design. The program for each of the classes was participation in the active sports: hockey, basketball, and/or roller skating; the "task" throughout each hour was to play vigorously and continuously. The boys' mean hourly activity following amphetamine was slightly but significantly less than that following placebo. This finding is contradictory to the hypothesis that improved attention to an active task on stimulant would result in increased motor activity, and suggests the possibility of an independent direct effect of amphetamine on the motor system.