Been watching the football World Cup and wondering why the players spit and snot so often? It’s a good question and one which baffled a saliva expert I turned to in North America, who wished to remain anonymous.
“I was surprised to hear from you that athletes indeed spit and snot a lot,” he told me. “Textbook knowledge states that individuals who exercise strenuously for extended periods experience dry mouth. Dry mouth results from sympathetic nervous system stimulation, which decreases saliva flow and increases saliva viscosity, making saliva stickier and stringier. For most types of exercise, a dry mouth is actually a bigger problem than drooling.”
Our unnamed expert had clearly never watched Brian McClair on the football pitch. The now 62-year-old played for Manchester United and Scotland, and beyond carving out a reputation for goalscoring and his intelligence on- and off-the-pitch, he drew infamy for, as The Guardian described it, “placing a finger on his nostril, flute-like, then blowing snot out of his other – so close to spitting we’ll count it as spitting”. Maybe North American sports folk simply have better etiquette?
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A deeper dig reveals that there is a greater body of evidence behind the physiological rationale behind McClair and his modern-day sporting snot-rocketeers than spitting itself. According to research, up to 74% of the general athletic population – that’s both elites and amateurs across the sporting spectrum – suffer from exercise-induced rhinitis or EIR. Which is an impairment to peak performance. That’s because EIR is inflammation of the nasal passage, which can lead to a runny nose, itchiness and sneezing.
The mucus flow chart is thus: you exercise hard, increasing airflow through the nose. This irritates nasal tissue, which release something called ‘inflammatory mediators’. These are substances emitted by cells in the immune system to modulate inflammation. All of this results in a snotty mess.
There are several triggers to this stream of snot in addition to your high-octane aerobics session. One is cold weather. Dry conditions don’t help, either. But one of the biggest culprits for swimmers is chlorine.
Why isn’t totally clear, but the most commonly accepted theory is that repeated exposure to chlorinated products, tied in with increase breathing rates from exercise, provides a gateway for allergens and pollutants to cross what’s known as the ‘epithelial barrier’. Essentially, this is the body’s primary physical, chemical and immunological barrier against external stimuli. The clearest example is your skin, which is the outermost epithelial tissue.
It’s been reported that spending just one hour in a chlorinated swimming pool is enough to increase airway epithelial permeability in swimmers, whereas no such effect was observed after exposure to a copper–silver disinfected pool.
You can’t cure EIR per se, but you can manage it. Wearing a buff will help if cold air is the cause. This also helps if the irritant is dryness, as your breath will moisten the buff. If you’re a swimmer, shower straight away afterwards. Use a saline nasal rinse, too.
Returning to our spitting theme, there’s no strong evidence that the cause is EIR, albeit there’s a plausible physiological connection due to the excess mucus and throat clearing. There’s also evidence that exercise cranks up the amount of protein secreted into the salvia, especially a kind of mucus called ‘MUC5B’. This mucus makes the saliva thicker, which makes it harder to swallow, so we spit it out.
