A device and method to detect force and provide feedback to a runner or jogger so that the person can judge whether to adjust his or her stride in order to lessen the impact on his or her body. The device includes a housing, a power supply, a piezo sensor, a controller, and an output generator. The piezo sensor is accommodated within a user's shoe and is connected to the controller, and the controller, output generator and power supply are accommodated within the housing. The controller is connected to the output generator so that it is set to generate a signal to the output generator when a threshold level of force signal is received from the piezo sensor. The sensor signals the controller when force from an impact is applied to the piezo sensor and the controller signals the output generator when one or more signals indicating threshold levels of force have been reached, and the output generator generates a perceivable signal in response to the controller's one or more signals.