Nike Training Club is one of the best free fitness apps that users can use for running only. This fitness tracking apps is dedicated to running workouts only and available for users since the lockdown. Professional runners can use these fitness tracking apps to get training for marathons. They can plan their entire workout considering factors like time, distance, and mood. In addition to this, they can do some customizations as well to their running goal, speed, and time which makes it the best free workout app.