A wearable device for monitoring a lactate threshold can include at least one magnet configured to provide a static magnetic field to an anatomical region, a power supply, and a radio frequency (RF) module connected to the power supply. The RF module can provide pulsating RF signals across the static magnetic field and emit energy into, and receive response signals from, the anatomical region over a period of time. The response signals can enable detection of a change in H+ concentration in the anatomical region, the change enabling detection of the lactate threshold. The wearable device can be used during a variety of exercises at selectable anatomical locations.
