Walk Run Off the Pounds

What Happens to Your Body on a 30-Minute Run In the First Few Seconds Your muscles start using adenosine triphosphate (ATP), energy molecules your body makes from food. More: 15 Foods That Will Power Your Workouts That burst of power you feel? In the First 90 Seconds In order to unleash more ATP, your cells break down glycogen, a form of glucose fuel stored in your muscles. More: How to Fuel for Your Workout Your body gobbles more glucose, and your muscles release lactic acid, also known as the burn in the age-old workout mantra "feel the burn", which signals the brain that you're under physical stress. In the Next Few Minutes Your heart starts beating faster and directing blood toward your muscles and away from functions you don't need at the moment, such as digestion. To make the best use of glucose, your muscle cells require an influx of oxygen. More: Breathing and Running: A Lesson in Oxygen Intake and VO2 Max All this burning of glycogen and oxygen raises your body temperature. Within 10 Minutes After 30 Minutes Whew!