Abstract: A device and method for monitoring electromyographic signals at a wearable health-data device that selectively monitors bioelectrical signals of a human body on a single limb. The device, such as a smart-watch or bracelet, has a body with a surface having at least two electrical contacts that are placed apart from each other and conductively held against the human body such that a bioelectrical electrical signal is passed between the two electrical contacts. There can be a computer platform contained within or on the device body that selectively monitors bioelectrical signals, isolates one or more electromyographic signals within the monitored bioelectrical signals, compiles respiratory effort data from the one or more electromyographic signals, and selectively outputs the respiratory effort data. An existing health-data device, with one body-facing contact, can also be modified with a fitting that allows dual contacts to be simultaneously held against the human body.