Tag Archives: salinity

Physiological effects of long and marathon swims – Salt Mouth

Salt Mouth

Unlike Third Spacing of Fluids, salt mouth is one of the most common and least visible or appreciated effects of marathon swimming and can cause the swimmer great distress and discomfort, and yet it’s invisible to everyone else.

Typical English Channel swimmer the day after
Typical English Channel swimmer’s throat

Salt Mouth is the effect of salt build up on the tongue and in the mouth and throat. The extent of the effect is directly proportional to the immersion time obviously, but less obviously to the salinity.

We sometimes speak about the limiting factors of distance swimming being hypothermia or jellyfish or currents, but salt mouth is also one of the most significant limiting factors for very long swims. At its worst salt mouth can inflame the throat, make swallowing nigh on impossible and the swim ends. Some swimmers even report shedding the entire surface of the tongue and throat.

For myself post-swim initial mild discomfort starts after about four or five in salt water. For a swim less than ten hours the discomfort doesn’t last more than 24 hours (e.g. Manhattan) and often only overnight.

However for longer swims the discomfort or even pain can be quite significant. After my English Channel, I had a lot of discomfort for over three days, to the extent that eating was painful. Lisa Cummins was in a lot more pain after her 35 hour two-way crossing, that took even longer to abate.

Alan Clack during a feed
Alan Clack during a feed

For those unused to swimming in the sea, a marathon sea-swim can be a painful experience with the salt mouth gradually building up from early on during the swim. Other swimmers may just notice a gradual loss of taste during feeds and not detect the extent of the build-up until after the swim.

I’ve said above that salt mouth is less obviously related to local salinity. This is because people often don’t realise the different saline levels around the world and often come from a lower salinity region. The south coast of Ireland is about 4% whereas the English Channel is about 4.5 to 5%. That’s a 15-20% increase. Over 5% isn’t even considered salt water but brine, (though we use the terms interchangeably). The west coast of the US for example is around 3 to 3.5%. Ocean temperature obviously affects salinity but so does ocean size and mixing. The Mediterranean Sea has higher temperatures and a smaller area so the saline solution becomes more concentrated.  In the English Channel the water is constantly pushed and pulled up and down the Channel by tides and can’t escape so the salinity increases.

Global ocean salinity
Global ocean salinity

The most usual method of combating salt mouth is for the swimmer to take a dilute mouthwash solution regularly during the swim. Undiluted mouthwash during a swim can the swimmer’s mouth to feel burned. Dilution rate is a personal choice, but usually 25%, 33% or 50%. I use 33% as I find 50% is still too strong. Frequency is also personal; Alan Clack asked for an increase of mouth wash during his Channel Solo, as he could feel his throat getting sore and he was getting a mouthwash about every 90 minutes and it seemed to work for him. Of course this needs to be always balanced against the time taken for the mouthwash.

The other key method of combating salt-mouth is to change your breathing pattern such that you are exhaling through your nose in salt water. Most experienced swimmers will exhale through both nose and mouth, especially in the pool.  This is partially related to the effort expended. But for a marathon swim the swimmer is maintaining a lower rate of exertion and it is possible with practice to exhale through the nose only, reducing the exposure of the mouth to salt water.

A method that hasn’t really been explored yet but which was mooted by a dentist friend is to line the inside of the throat with a protective barrier. Should this happen, it will doubtless be a future area of rules contention.

Karen Throsby says the black jelly babies are best

Kendal mint cakeApart from these two methods swimmers choose various food items which seem effective at temporarily combating or relieving salt mouth. Tinned peaches and jelly babies are amongst the most popular. Ice-cream after swims is also popular for this reason. I found Kendal Mint Cake useful during training swims. For those unaware of Kendal Mint Cake, it isn’t a cake but compressed glucose with a slight hint of mint, famously used in early 20th Century mountain-climbing and polar expeditions and still very popular with climbers for its compact size and high energy content. Later in swims though as the mouth cools it is difficult to melt and swallow.

Overall Salt Mouth should not be dismissed as a mere inconvenience but as another of the potentially serious limiting aspects of swims, which require consideration during training and investigation of preferred methods of alleviation.

EDIT: Have a look at English Channel Soloist and Utah resident Gordon Gridley‘s extreme salt tongue photo in the comments below. Gordo trained and did his English Channel qualifier in the Great Salt Lake, where salinity is far greater than the open ocean.

Salt of the Earth

EDIT: Yes, this post has been published twice. There was a backend problem on WordPress. Sorry.

NASA just released a cool new map of the world’s ocean’s salinity. I wish we could see the North Atlantic in better detail. It’s still early days for this though so there’ll be more to come. I look forward to seeing more detail for the North East Atlantic, English Channel, Mediterranean etc.

“On the colorful map, yellow and red represent areas of higher salinity (or salt content), with blues and purples indicating areas of lower salinity. Areas colored black are gaps in the data.

Known as Aquarius, the instrument is making NASA’s first space observations of salinity variations on the ocean surface — a key component of Earth’s climate that influences ocean circulation and is linked to the cycling of freshwater around the planet.

So far, the instrument is performing better than NASA scientists expected. The new map was made from Aquarius’s first two-and-a-half weeks of data.

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The new Aquarius map reveals predominantly well-known ocean salinity features, such as higher salinity in the subtropics, higher average salinity in the Atlantic compared with the Pacific and Indian oceans, and lower salinity in rainy belts near the equator, the northernmost Pacific Ocean and elsewhere.

These features are related to large-scale patterns of rainfall and evaporation over the ocean, river outflow and ocean circulation. Aquarius is built to monitor how these features change over time, and study their link to climate and weather variations.”

From: http://www.nasa.gov/mission_pages/aquarius/multimedia/gallery/pia14786.html.