Your stomach is a particularly active organ, it always secretes acids and hormones and shakes everything inside to prepare it for water absorption in the small intestine. As a result, it is a noisy organ, and it is rare to go more than a few hours without your stomach giving you an audible reminder of its presence. Running can cause an even greater amount of roar than normal, due to the deep breathing that accompanies running.
What are the causes of the sound of your stomach?
You have drunk too much liquid
It is very likely that you will drink a considerable amount of fluid before starting a race, especially a race that you expect to last 45 to 60 minutes or more. Even in mild conditions, your fluid losses can be considerable, and in hot climates you need to drink water or a sports drink not only before the race, but also at 15-minute intervals during the race. This inevitably results in a great deal of gurgling and splashing in your stomach. If you don’t experience cramps or nausea, noise, while distracting you, is not a cause for concern.
Bloodshed
When you run, more than usual blood is pumped to your leg muscles to meet oxygen requirements. You only have a large amount of blood, so this occurs at the expense of the blood supply to other tissues, including your stomach.
This preferential diversion of blood from the intestine to the muscles causes a marked slowdown in digestion. This can cause cramps if you are not particularly fit, while if you are well trained, you may not notice anything more serious than a lot of gurgling noises.
Empty stomach
Some people like to exercise a few hours after a normal meal, others like to have an energy bar or two in the hour before they walk out the door, and others swear to run on an empty stomach. If you are in the latter group, be aware that although you may feel more comfortable in these conditions, your stomach will remind you that it is empty, especially as your run stretches for an hour and your body incurs a greater calorie deficit . The idea that running on an empty stomach leads to increased fat burning is widespread in the exercise community, but the evidence for this idea is equivocal at best.
Diaphragmatic compression
The act of breathing involves the creation of a negative pressure gradient between the lungs and the external environment. At the end of a normal exhalation, these pressures are the same. The contraction of your diaphragm, a dome-shaped muscle attached to the bottom of your lungs, causes the diaphragm to flatten and move downward in your center. In doing so, it drags the bases of the lungs with it, expanding them and causing air to enter them to equalize the pressure. As the diaphragm moves downward, push against your sitting stomach just below it. Depending on the contents of your stomach, this can create some gurgling noises, with deeper breaths that can cause more gurgling.
