Detection device and monitoring system for detecting an exercising state

A detection device (10) and a monitoring system are adapted to detect an exercising state of a user. The detection device (10) is adapted to be equipped on a circulation exercise device (21) of a physical training equipment (20). The detection device (10) has a state detector (11) and a rotation speed detector (12). The state detector (11) generates multiple signal combinations based on a periodic motion of the circulation exercise device (21). The rotation speed detector (12) estimates a relative variation between a rotation speed and degrees of the circulation exercise device (21) based on the signal combinations. The relative variation represents the user's exercising state. According to the relative variation, a user can realize whether the exercising state is in balance.