Musculoskeletal disorders are the highest cause of work absenteeism according to the World Health Organization. The traditional solution to address this problem involves guides depicting exercises to perform. However, these exercises are only successful if the worker engages in the repetitive routines without any supervision, resulting in reasons not to practice the exercises. Some of these are the lack of time, interest, motivation, feedback and proper guides. Another issue is the assessment process that involves subjective analysis from surveys and observation. These challenges are addressed through motion tracking and virtual reality. Tracking allows quantifying the exercises through motion measurements through various sensors. Virtual reality allows the worker to engage in fun and challenging interactions while exercising. This work presents the development of a knee flexion and extension motion exergame. Two tracking approaches using image processing and inertial sensors (using a smartphone and an open electronics wearable) were implemented and tested for accuracy and reliability. The systems were compared and analyzed as complementary tools in occupational and fitness scenarios.