When using fitbit and counting steps, does it go off of arm movements?

Accelerometer: I first learned of this device at a conference last summer. I have used myself and recommended for many of my patients. It nicely gives you on line updates and links to apps on your phone like myfitnesspal. It is based on a technology called an accelerometer, which measures your acceleration through space. You can't fool it by swinging your arms or shaking it in your hand.