All of us have felt pain in the left side of the abdomen after running or laughing. No place for panic, it is something completely normal and happens to everyone.
Running and laughing are activities that have one thing in common, they cause diaphragm cramping. If you laugh hard, you breathe more air, to widen the lungs and thus push the diaphragm downward. At the same time, your abs is activated and pushes up the same organ. All this repeats many times in a minute.
This “condition” of the diaphragm leads to pain. The same happens during running. However, if during the running or laughing you feel strong unbearable pain, together with pain in your right arm, than it may be something more serious, because these symptoms can appear before heart attack.
But they also can be linked with cramps because the nerve located in the diaphragm goes in the right arm. To avoid this, try to laugh repeatedly. Between two short periods of laughter, pause with two deep sighs. Also, try to avoid heavy meals before running.