The fitness band that never sleeps Garmin plans to go head-to-head with Fitbit following the launch of its latest gadget, the Vivosmart 4 activity tracker. This sleek new wristband not only tracks steps, activities and monitors the weather but it also comes with a blood oxygen sensor and will tell you how much energy you have saved up for your next full throttle burn session. This new body battery energy calculator estimates the body’s energy reserves to help you figure out when you feel more rundown and why. You simply swipe through the menu on the display to get to your energy levels or a number of other data offerings like steps, heart rate, stress levels and the number of stairs climbed. The blood oxygen sensor will tell you how well oxygen is being pumped from your heart to the farthest regions of your body and can help you figure out if you are getting a good sleep in.