Two groups of Boston-based health researchers are partnering with Apple on a pair of medical studies that began to collect data from the public Thursday. Apple first announced in September its plans to allow Apple Watch and iPhone owners to contribute data to health research through the Apple Research app, which was released Thursday. One of those research projects, the Apple Heart and Movement Study, is being conducted in partnership with Brigham and Women’s Hospital and the American Heart Association. The groups said the study intends to learn about how mobility and heart rhythm could serve as potential early warning signs of heart issues, such as atrial fibrillation or heart disease. "Users can participate by using the Research app on their iPhone and recording workouts on their Apple Watch Series 1 or later," Apple officials said.Dr. Calum MacRae, of Brigham and Women's Hospital, is principal investigator of the project, which will run for the next five years. For the Apple Women's Health Study, the technology company is joining forces with the Harvard T.H. Chan School of Public Health and the National Institutes of Health's National Institute of Environmental Health Sciences. In that project, the Apple device users will be asked to provide data about their menstrual cycles and respond to monthly surveys. "The study seeks to analyze the impact of certain behaviors and habits on a wide breadth of reproductive health topics," Apple officials wrote. The third study, which also began to collect data Thursday, is examining hearing health and stress levels. Apple is partnering with the University of Michigan on that study. Apple said the newly launched Research app will only share data with a user's approval and that the app includes detailed consent information for each of the three studies.