On touch control touched - set platform speed to whatever speed you want the run to be, wait X seconds, set speed to original speed.
You can make it more robust by setting up a variable and a timer:
If variable = false, when key pressed, set variable to true.
If variable = true, set platform speed to X speed; wait X seconds, set variable to false
if variable = false, set platform speed to original speed.
You could also add a cool down variable if you wanted to make sure the player couldn't run repeatedly without a rest. So if the variable you set up is false, and the cool down timer is greater than 0, you subtract 1 from the timer every 1 second. If the variable is false AND the cool down is 0, then you can run. When the variable is true, you set the cool down to whatever you'd like (maybe 3 seconds is good for the sake of argument).