A wearable physiological measuring device has a torso-worn module and a limb-worn module configured to communicate in a wireless way with each other. The torso-worn module is configured to be coupled with a torso of a user to obtain an R-peak from an electrocardiac signal. The limb-worn module is configured to be coupled with at least one limb of four limbs of the user to obtain a pulse wave peak from a plethysmograph signal. There are no physical connections (neither wire nor cable) between the torso-worn module and the limb-worn module. The wearable physiological measuring device is configured to use the R-peak time and the pulse wave peak time to generate a pulse transit time data.
