We report on our extended research on GymSkill, a smartphone system for comprehensive
physical exercising support, from sensor data logging, activity recognition to on-top
skill assessment, using the phone’s built-in sensors. In two iterations, we used principal
component breakdown analysis (PCBA) and criteria-based scores for individualized and
personalized automated feedback on the phone, with the goal to track training quality and
success and give feedback to the user, as well as to engage and motivate regular exercising.
Qualitative feedback on the system was collected in a user study, and the system showed
good evaluation results in an evaluation against manual expert assessments of videorecorded
trainings.