Run Science

Your Body on a Run: From Start to Finish
Let’s take a walk—or rather a run—through how the body creates and expends the energy necessary to keep you moving forward.

Phase 2
When you first launch into your run, your muscles rely on adenosine triphosphate (ATP) to get you moving. These molecules are created by the food you eat and are stored in glycogen within your muscles and your blood. Glycogen is the body’s energy storage unit, waiting to be delivered and opened for use. As you continue to move, more ATP is unpacked from these glycogen storage units and is consumed by your muscles to keep you running, you can also help your body with juicing strategies and supplements. 

Phase 2
As you continue on your run, your muscles begin to release lactic acid to signal to your brain that you’re working, and physical activity is underway. In order for your muscle cells to continue to break down glucose, they must use oxygen to do so. Therefore, your body begins to shunt blood away from non-essential functions such as digestion and begins to bring oxygen to areas in need. In order to pull in and provide more oxygen to your system, you begin to breathe heavier.

Calorie use also begins to increase as your body rapidly moves through the energy expenditure cycle. Your core body temperature rises, and your blood vessels dilate to bring blood nearer to the skin to be cooled. This results in redness and flush. You also begin to produce sweat in order to cool off your body and prevent heatstroke.

Phase 3
If you have built up your endurance, your body will settle into a sustainable cycle of breathing, sweating and breaking down glucose into ATP. If you have been neglecting your workouts or you are new to the practice of getting in a good number of runs per week, your body may not be able to use energy as efficiently, and your use of ATP will begin to lag. Lactic acid will build up, your muscles will begin to ache and running will become a chore as your body struggles to keep up with the cycle of energy supply and demand.

Phase 4
During your cool-down period as your pace slows and you revert back to a walk, your breathing will return to normal, your heart rate will slow and the demands on your body to continue to produce energy in short order will wane. Along with a general feeling of physical accomplishment, the endorphins triggered by your run should now have you in a great mood, ready to tackle whatever comes next in your day.

Running is a great way to combine the efforts of many different physical practices into one. It increases endurance, builds muscle to maintain an optimal body fat composition, promotes cardiovascular health, strengthens the heart, and even improves your overall mood. Combined with weight training, running can help you maintain the perfect balance of mental stimulation and physical fitness.