Jawbone UP 3Fitness wearables started off with the modest task of tracking your daily steps. Now, they're measuring your heart rate while automatically figuring out exactly what your current activity is, whether it's running, cycling, or whatever else you do to stay in shape. The Jawbone UP 3 uses bioimpedance sensors to measure your heart rate, and Jawbone promises to deliver over-the-air updates so the sensor can measure other physiological signals, like respiration rate.
