Side Aches: What’s the story?

May 16, 2018

Running expert Nate details several theories behind the dreaded side ache

If you have been a runner long enough, you’ve experienced the “pleasure” of having a side ache — that debilitating, stabbing pain somewhere around your lower rib cage that cuts your run or race short. I once had one so bad that I only made it a quarter mile into a run. I stretched, relaxed, did some additional warm-up drills and went back to running.  Ten steps later it was back with a vengeance and at that point I walked home and called it a day.

So what is the cause? There are many theories, but ultimately the true cause is still an enigma.

Theory 1: Too much content in the stomach

If you have a lot in your stomach and then go do an activity that jostles things around, you might get a side ache. The thought process is that the full stomach pulls on the diaphragm, which eventually doesn’t like the extra tug and it starts to spasm and create a side ache. It’s a good, plausible theory … but the problem is that swimmers and bikers get side aches, too, so this can’t always be the case.

Theory 2: Inconsistent breathing

Riding on bumpy terrain, riding a horse and other activities can cause shallow, quick and inconsistent breathing. If you experience this, you just might end up with a side ache.
The theory is that the inconsistency and randomness of the inhale and exhale lead the diaphragm to spasm, causing the side ache.

Theory 3: Lack of proper warm-up

Your short of time so you head right into the workout and get after it. A few minutes later you are standing around waiting for a side ache to subside. The theory on this one is that if you came from a “rest and digest” state, your blood is primarily in the gut. Instantly starting an intense workout with no warm-up will get the cardiovascular system working quickly, but there’s a bit of a lag time to redirect blood from the gut to the working muscles. This is thought to lead to an oxygen deficit to the diaphragm, which leads it into a spasm and side ache.

Theory 4: Nervousness

This is from personal stories people have told me — when none of the theories above apply, and yet a side ache occurs. In many cases, the individual was in a race or hard workout situation that he or she was nervous about. We know that neural fatigue plays a major role in muscle cramps, so this might be the cause with this one, as well.

If one of these scenarios is causing your side ache, you may now be able to identify the fix. For some people, none of these theories provides any answers. If you do happen to solve this puzzle, please share with the rest of the world so we can eliminate side aches forever.


Always running,

Nate Vandervest