Greetings, Floridarunner. I’m sure it’s tough running this time of year, when the morning low temps are 80 degrees or above! Always seems like I need more air when I run in the heat, and this can put a bit of a strain on the breathing muscles. While that could have a lot to do with the onset of pain as you get into a full breathing cadence, there are a few more things to check.
If you have had any slips or falls leading up to your pain, there may indeed be a strained muscle in your trunk or abdomen that begins to complain as you settle into your exercise. Some muscles in the sides, chest, and abdomen may only complain after repetitive use, as in running or other aerobic exercise.
It’s important to state here that muscle pains do not always go away after rest. They often have to be dealt with directly before the symptoms of a muscular strain begin to disappear. Stretching and/or exercise sometimes will aggravate a muscle strain, so I will give you some tips for exploring and possibly correcting the condition.
Get into a relaxed position, laying on your back to deactivate the abdominal muscles. Put your hands together as if shaking your own hand, and use the supported fingers to gently probe the intercostal muscles between each of your ribs on the front and sides of your chest, looking for tender spots. A pain that seems to appear in different places along your side as you exercise can indeed start in a single spot that triggers a protective contraction in response to stimulus. If you find a tender spot between your ribs, don’t poke too hard. There is a happy middle ground between not enough and too much pressure, when it comes to releasing a latent muscle spasm. Try to gently rub out the tenderness without irritating it further.
You are also going to need to check your center abdominal muscles, from below the belt line to just under the bottom ribs where the edge of your diaphragm muscle resides (avoid putting pressure on the very center of this spot). What we often call the “six pak” or rectus abdominus is in a band a few inches wide along this path, joining the pubic region of the pelvis to the lower ribs. These muscles can get pulled during ab crunch exercises or other exertion like jumping and hurdling. They are instrumental when kicking or during any kind of “goose step” motion, as they brace the pelvis when the thigh is flexed forward or upward (as in running). Slouching in a lounge chair can be particularly counterproductive. Easy to strain, but can be easy to fix.
Using your fingers again, probe this long abdominal muscle along its full length, including the edges, paying close attention to either end where its attachment can be strained. You are again looking for tender or reactive spots where the muscle may be injured or in a state of latent spasm, often known as a “trigger point.” This is not as easy to check after a large meal, when the abdomen may be distended. Make sure the area is in a relaxed state before applying pressure.
At the upper end of the abdomen, you can check the edge of the diaphragm muscle itself by flattening your stomach while chest breathing, and feeling for the muscle underneath the edge of the lower ribs. The diaphragm contracts to pull air into the chest, and various muscles around and between the ribs are used to squeeze air back out of the lungs during exhalation. The pain you feel may occur during either part of the cycle, when the involved muscles are being contracted or stretched. The point is to check all of them for tender spots that may trigger a spasm during heavy breathing.
It sounds like you have been careful to check dietary factors that can contribute to the classic side stitch. I am adding my personal and professional expertise to address the common muscular contributions to this type of problem, but this is by no means an exhaustive list. There are other muscles involved with the twisting, bracing motion of running. If you don’t find anything after these efforts, a checkup may be advisable to look for a circulatory or GI cause for your pain. If nothing is found by an MD, you can safely get more technical about training.
It is often said the the average runner will continue to progress for approximately 10 years while continuing to train. Since you could be at or near the end of that progression, it is important to accept your fitness at this point, and avoid pushing yourself too hard in an attempt to go much faster or farther than you already have. Since it takes most people at least a few marathons to reach their peak potential at that distance, it’s hard to resist the temptation to over-train. If you are holding yourself to specific time goals during your training runs, in order to achieve a target time in the target marathon, a setback like this one may indicate that your goals are too ambitious. Then again, it may just be the weather.
During the hot months, a good rule of thumb is to add a minute per mile to your training for every few degrees of temperature rise, to compensate for the added strain. If you are training for a Florida marathon, you have plenty of time left to get your speed back when the weather is more favorable. Again, if you can’t run without pain, it’s time for a break, and probably a checkup. Good luck!