To start the training clock, press the "Play" button located at the bottom center. When this button is pressed, all the buttons necessary for the training tools appear. If you want to pause the training timer, first press the "Clock" (button on the bottom left). Now you can choose between the different timer functions within the training. The "Pause" button for the training clock is located below the stopwatch (third button from the top). If this button is pressed, the "Play" button appears again and all other buttons at the bottom disappear.