The invention relates to a communication module, monitoring unit and method of monitoring a physical performance. The module has a receiving unit, processing unit and wireless communications unit. With these units the module continuously receives sensor signals from a sensor connected to the communication module, processes the sensor signals to form a plurality of successive data messages containing data at least partly derived from the sensor signals, and transmits the formed data messages to an external wireless receiver device at a plurality of successive transmission time slots using a wireless communication protocol. The processing unit is adapted to add information to the data messages regarding the difference between first time points based on predefined characteristics of the sensor signals and second times points corresponding to transmission slots. The invention allows for relating the individual signals temporally with each other for better overall analysis of the performance.
