A system comprising: a server computer comprising at least one processor and at least one memory configured to store training data of one or more users; a plurality of data collector devices, each of the plurality of data collector devices being associated with a gym device or an exercise spot of a gym, wherein each data collector device comprises a wireless communication unit, and a memory configured to store training data of a user; one or more time-of-flight positioning units configured to be disposed at fixed locations in the gym and conduct time-of-flight positioning; one or more mobile tag devices, each mobile tag device comprising a time-of-flight positioning unit configured to conduct the time-of-flight positioning together with the time-of-flight positioning units at the fixed locations; and one or more wearable devices, wherein each wearable device is associated with one of the one or more mobile tag devices, and each wearable device comprises a wireless communication unit, and a memory configured to store training data of the user, wherein the system is configured to: track locations of the one or more mobile tag devices with respect to the data collector devices in the gym as a result of the time-of-flight positioning; determine, on the basis of the tracking, whether or not a location of a mobile tag device is within a pairing area of a data collector device; and if the location is determined to be within the pairing area, trigger establishment of a wireless connection between a wireless communication unit of the data collector device and a wireless communication unit of a wearable device associated with the mobile tag device, and transmit training data between at least two of the data collector device, the wearable device, and the server computer. a server computer comprising at least one processor and at least one memory configured to store training data of one or more users; a plurality of data collector devices, each of the plurality of data collector devices being associated with a gym device or an exercise spot of a gym, wherein each data collector device comprises a wireless communication unit, and a memory configured to store training data of a user; one or more time-of-flight positioning units configured to be disposed at fixed locations in the gym and conduct time-of-flight positioning; one or more mobile tag devices, each mobile tag device comprising a time-of-flight positioning unit configured to conduct the time-of-flight positioning together with the time-of-flight positioning units at the fixed locations; and one or more wearable devices, wherein each wearable device is associated with one of the one or more mobile tag devices, and each wearable device comprises a wireless communication unit, and a memory configured to store training data of the user, wherein the system is configured to: track locations of the one or more mobile tag devices with respect to the data collector devices in the gym as a result of the time-of-flight positioning; determine, on the basis of the tracking, whether or not a location of a mobile tag device is within a pairing area of a data collector device; and if the location is determined to be within the pairing area, trigger establishment of a wireless connection between a wireless communication unit of the data collector device and a wireless communication unit of a wearable device associated with the mobile tag device, and transmit training data between at least two of the data collector device, the wearable device, and the server computer. track locations of the one or more mobile tag devices with respect to the data collector devices in the gym as a result of the time-of-flight positioning; determine, on the basis of the tracking, whether or not a location of a mobile tag device is within a pairing area of a data collector device; and if the location is determined to be within the pairing area, trigger establishment of a wireless connection between a wireless communication unit of the data collector device and a wireless communication unit of a wearable device associated with the mobile tag device, and transmit training data between at least two of the data collector device, the wearable device, and the server computer.