Garmin leak hints at muscle sensor with major benefits for strength athletes

Endurance athletes can gain detailed insights into their performance using just a smartwatch, which pairs a GNSS module for accurate distance, speed, and power tracking with heart rate monitoring. Strength athletes, however, face greater limitations: a smartwatch cannot track lifted weight, and heart rate is a far less reliable indicator of physical exertion during resistance training. While sensors capable of directly measuring muscle load already exist, Garmin appears to be developing a system of its own.

According to a report from Gadgets & Wearables, concrete references to this feature have surfaced within the Garmin Connect app. Specifically, the app contains data fields for average, minimum, and maximum levels of oxygen-saturated hemoglobin, as well as total hemoglobin concentration. This would enable users to monitor these metrics throughout a workout. A drop in muscle oxygen saturation—the percentage of oxygenated hemoglobin—typically signals muscle fatigue. Tracking this data could help athletes optimize rest periods between sets and assess localized exertion more accurately.

Unlike general blood oxygen saturation (SpO2) or heart rate, muscle oxygen levels are localized rather than systemic. As a result, a sensor must be placed directly on the targeted muscle—such as the quadriceps during leg extensions or the chest during bench presses. Exactly how Garmin plans to design and implement such a hardware system remains unclear.