A ventilation measurement device includes a fastening mechanism capable of permanently or detachably fastening the ventilation measurement device to a belt which can be worn around a person's chest. The device includes a substrate coupled to the fastening mechanism and capable of receiving tensional forces transmitted from the flexible belt through the fastening mechanism. A strain gauge is mounted on said substrate and is configured to output a signal with a functional relationship with said tensional forces to a controller unit. The controller unit is configured to receive and process the signal to produce processed data from the strain gauge signal, and to control a transmitter configured to transmit processed data to an external receiver.