Garmin has reportedly acquired Moxy Monitor, a specialist wearable company that measures oxygen levels inside working muscles. Neither company has formally confirmed the transaction, although Moxy founder Roger Schmitz reportedly redirected questions about the deal to Garmin.

Moxy already works with Garmin watches and Edge computers through Connect IQ. Its $879 sensor is worn directly over muscles such as the quadriceps or calf, giving athletes another physiological signal alongside heart rate, power, and pace.

Measuring oxygen inside the muscle

Moxy uses near-infrared spectroscopy, or NIRS, to shine light into muscle tissue and estimate muscle oxygen saturation, known as SmO₂. The metric reflects the balance between how much oxygen is being delivered to a muscle and how much it is using during exercise.

Athletes can use those changes to monitor workout intensity and see how quickly a muscle recovers between efforts. The sensor also measures total haemoglobin and updates its data up to twice per second.

The sensor has to be placed precisely. Muscle oxygen is a local measurement, so a sensor on the wrist cannot tell Garmin what is happening inside the quadriceps during a hard cycling interval. Any future Garmin implementation would likely still involve a separate sensor positioned over the muscle.

Garmin keeps expanding its performance stack

The reported acquisition fits several recent Garmin moves. In July, the company acquired TrainingPeaks and TrainHeroic, expanding further into training plans, coaching, and performance analysis.

Garmin also filed a US trademark for Muscle Battery earlier this year, covering software that analyses muscle oxygen saturation and related performance metrics. Moxy could provide the IP needed to materialize that feature.

Published studies have found Moxy capable of reliably tracking changes in muscle oxygen, although the technology is still considerably more specialist than the heart-rate metrics or GPS tracking that now is central to any wearable.