A training baseball bat has an internal movable magnet that accelerates to the end of the bat when swung at a fast enough speed. As the magnet moves it passes through a coil that is connected to one or more LEDs so that the LEDs momentarily flash as the magnet moves through the coil. A stationary magnet can be used to hold the movable magnet until sufficient centrifugal force is imparted by the swing to overcome the magnetic holding force. Spacers can be provided to establish a distance between the magnets as needed to establish a desired swing speed at which centrifugal force overcomes the magnetic attraction.