GRec is for medical research, to record g-force events caused by muscle twitches. It uses the device's built-in gyroscopes, so no external sensors are needed. What might be needed is an external battery if monitoring times of many hours are needed. The phone can easily be attached to a patient's arm or leg by using widely available phone arm bands. The app records events when triggered by the g-force exceeding a value that can be set between 0 and 3g. A good practical value is between 0.5 and 1g. The recording is compensated for gravity, so only patient induced g-forces are recorded and shown in the graph. Each event is recorded as a 2 second waveform, with the trigger in the center of the timeline, so 1 second before and 1 second after the trigger moment is recorded. The maxima of x, y, z and vector within that timeframe are displayed below the graph. Also the date and time of the event are displayed. Above the graph you can input the patient data before starting the study. Events are stored as screenshots in your photo library inside a new folder that the App creates, named GRec. At the first trigger event the App is ever used on a device, it will ask for permission to store screenshots in your photos library. Since this is an application for medical research, you might have the need for additional features. Feedback with such suggestions is welcome.