A method comprising: receiving, by a wearable device, a location signal from a positioning device having location-determining capabilities indicative of a location of the positioning device, wherein the wearable device includes at least one sensor configured to measure at least one physiological parameter; calculating, a first location of the wearable device based, at least in part, on the location of the positioning device and a strength of the location signal received by the wearable device; characterised in that, in response to loss of the location signal at the wearable device after calculating the first location of the wearable device, the method further comprises: storing, on the wearable device, the first location of the wearable device; and storing, on the wearable device, wearable device movement data received from one or more movement sensors located on the wearable device and a timestamp associated with the wearable device movement data, wherein the wearable device movement data is indicative of movement of the wearable device; and in response to reestablishing the location signal at the wearable device: receiving, by the wearable device, an updated location signal from the positioning device and a timestamp associated with the updated location signal, wherein the updated location signal is indicative of one or more updated locations of the positioning device; correlating the wearable device movement data and the updated location signal based, at least in part, on their associated timestamps; and calculating an updated location of the wearable device based, at least in part, on the wearable device movement data correlated with the updated location signal, a strength of the updated location signal received by the wearable device, and the first location of the wearable device. receiving, by a wearable device, a location signal from a positioning device having location-determining capabilities indicative of a location of the positioning device, wherein the wearable device includes at least one sensor configured to measure at least one physiological parameter; calculating, a first location of the wearable device based, at least in part, on the location of the positioning device and a strength of the location signal received by the wearable device; characterised in that, in response to loss of the location signal at the wearable device after calculating the first location of the wearable device, the method further comprises: storing, on the wearable device, the first location of the wearable device; and storing, on the wearable device, wearable device movement data received from one or more movement sensors located on the wearable device and a timestamp associated with the wearable device movement data, wherein the wearable device movement data is indicative of movement of the wearable device; and storing, on the wearable device, the first location of the wearable device; and storing, on the wearable device, wearable device movement data received from one or more movement sensors located on the wearable device and a timestamp associated with the wearable device movement data, wherein the wearable device movement data is indicative of movement of the wearable device; and in response to reestablishing the location signal at the wearable device: receiving, by the wearable device, an updated location signal from the positioning device and a timestamp associated with the updated location signal, wherein the updated location signal is indicative of one or more updated locations of the positioning device; correlating the wearable device movement data and the updated location signal based, at least in part, on their associated timestamps; and calculating an updated location of the wearable device based, at least in part, on the wearable device movement data correlated with the updated location signal, a strength of the updated location signal received by the wearable device, and the first location of the wearable device. receiving, by the wearable device, an updated location signal from the positioning device and a timestamp associated with the updated location signal, wherein the updated location signal is indicative of one or more updated locations of the positioning device; correlating the wearable device movement data and the updated location signal based, at least in part, on their associated timestamps; and calculating an updated location of the wearable device based, at least in part, on the wearable device movement data correlated with the updated location signal, a strength of the updated location signal received by the wearable device, and the first location of the wearable device.