From as early as I can remember, I was warned that I needed to wait at least 30 minutes after eating before I could get into the water, and that if I went in any earlier, I would feel the symptoms of a dreaded cramp.
Because of these warnings, I’ve never gone swimming right after eating. Even as a competitive swimmer, I would wake up almost 30 minutes ahead of my 4:30 am practice — just so I could eat something to provide me with energy for my two-hour session. This notion that I used to believe, however, turned out to be completely false. It is a myth that eating before swimming will cause muscle cramps — but where does that myth come from?
It comes from research about your blood flow after you eat. When you ingest food, it passes through your gastrointestinal tract, and blood gets diverted primarily from your skeletal muscle tissue to your stomach and intestines. Additionally, the blood that is being pumped more rapidly from your heart is sent to aid indigestion.
What many don’t realize is that the amount of blood that does rush toward your stomach is not nearly as significant as many believe — it’s certainly not enough to lose all the energy in your muscles.
Even if your muscles experience sufficient blood loss, it won’t guarantee you a cramp. If anything, muscle cramps have been shown to be caused by a lack of potassium, calcium, carbohydrates, and proteins. You’d need to have a serious medical condition that greatly impacted blood flow, like kidney or thyroid disease, to greatly reduce the blood in muscles.
If cramps are not caused by eating before exercising, why does this myth continue to persist today? Probably because most people have a very limited understanding of the extensive actions of the human body and can’t detect the slight differences between a muscle cramp and a stitch.
A stitch, which is medically referred to as Exercise Related Transient Abdominal Pain, is a very common abdominal pain that can consist of sensations ranging from sharp stabbing to aching and pulling. It is the bane of many athletes’ lives. Similar to cramping, almost no one has any idea what brings about stitches or how to prevent them, but studies have been conducted to better understand them. Dr. Darren Morton, a scientist and lead lecturer at Australia’s Avondale College of Higher Education, has dedicated most of his career to stitches.
His research has spawned numerous theories as to what causes a stitch and how it can be prevented. One common component typically mentioned is the aforementioned practice of eating before exercising. Unlike muscle cramps, stitches are usually localized in the stomach and diaphragm area.
Theories of a cause include everything from an irritation of the parietal peritoneum — the two layers of membrane that line the inner wall of the abdominal cavity — to the pulling of ligaments that connect the gut to the diaphragm. Eating just before exercising, especially eating larger meals and having a fuller stomach, has been shown to exacerbate stitches or stitch-like abdominal pain. This could be due to the fact that the parietal peritoneum is attached to various nerves, and a full stomach can cause friction between the abdominal contents and peritoneum or it could even pull on the ligaments and create stress on the diaphragm.
Eating before exercising may very well be a cause of many health issues, but cramps are not among them. Having a full stomach could make you sluggish, slow, and may make you prone to stitches, so it is better safe than sorry when it comes to partaking in sport shortly after eating. If anything, you might experience some pain and discomfort, but eating will not impede your muscles from fully functioning. If you experience pain, get out of the water and take a break.