This case study is about personal trainers’ perception of fitness applications and what their views are on the subject. The underlying problem is that most users uninstall the applications due to different reasons.The research questions were what factors affect the usage of fitness applications, and what functions that could be implemented to increase the usage of fitness applications.The theory behind the study is the international standard for usability, ISO 9241-11, and the outcomes of it. These outcomes or factors are effectiveness, efficiency, and satisfaction.The study investigated further with the help of interviews in attempt to find out what contributes to these usability factors, according to personal trainers because of their expertise in fitness.The conclusion is that each usability factor, effectiveness, efficiency, and satisfaction is achieved depending on a user’s knowledge and experience within fitness. Effectiveness is achieved depending on the user’s experience. The efficiency of the fitness application is increased depending on how satisfied a user is with the application and how well made it is. The usability as a whole is more beneficial to someone who is new to training and fitness, not so much for those who are experienced in the area of fitness. A couple of implementations that were suggested are a form check implementation which checks the form of an exercise and presentation of content in an informative way that keeps the users’ focus on the workout.