Understanding hypothermia in swimmers – Mild Hypothermia

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When all fails and I am at a loss for something to write about, I can write about cold, my favourite subject. Especially in the context of Cork Distance Week coming in two weeks, when we had a few people pulled from the water with hypothermia last year.

For anyone involved in open water swimming in Ireland, the UK and other Northern Hemisphere cold water locations, being able to spot and diagnose dangerous hypothermia in a swimmer is an essential skill. To do that properly an understanding of hypothermia is useful.

It’s essential to understand that there is no such thing as sudden hypothermia. Most of us grow up hearing this myth, (for example I remember stories of survivors from the Titanic freezing to death in five degree water within fifteen minutes, and that fifteen minute myth is repeated all the time).

The heat in your body can’t instantly disappear. The Second Law of Thermodynamics is always the Universe’s governing and inviolate principle. Hypothermia is a developing situation over time. Your body has enough stored heat that even in zero degree water, you probably won’t develop severe hypothermia until about thirty minutes, though you will be subject to After-drop and potentially lethal consequences even if you emerge before that time. And Afterdrop itself isn’t a myth, as is sometimes inversely claimed to sudden hypothermia, it does exist.

Cold shock response is an entirely different thing to hypothermia, it’s the bodies response to sudden cold, with gasping reflex, hyperventilation and possible acute pain in hands, feet, face and head, and even cardiac events. The biggest danger in immersion is uncontrolled hyperventilation leading to sudden aspiration of water. You gasp and breathe water into your lungs and drown.

Breathing rate increases for the first 20 seconds in cold water

This is the main reason why a diving or jumping entry into cold water for people not cold-acclimated is absolutely a stupid thing to do, and not tough or macho. This response is attenuated in cold-adapted swimmers.

Definitions of Mild Hypothermia can vary depending on where you look but a core body temperature of between 35° and 36° when body-normal is 37° is a good measure, i.e. a drop of about two degrees is a good indicator. The hormone ADH, (anti-diuretic hormone) which controls urination in suppressed and some blood volume is shunted to the core so there is a decrease in blood volume and some dehydration also. There are no long-lasting effects of mild hypothermia, (such that it can be used as a medical procedure for brain protection during certain operations). Almost every serious open water swimmer in these waters will have experienced it as completely normal, and the body acclimates and adapts as we have seen before, by blunting initial response, reducing stress hormones, and increasing brown adipose tissue.

However, people with any diagnosed cardiac problems should avoid cold water swimming.

And also as we’ve often discussed previously, mild hypothermia leads to peripheral vaso-constriction, the reduction of blood flow in the periphery. With experienced open waters mild hypothermia is the completely normal and usual state, in Irish and UK waters. The swimmer will still be able to talk and will still retain motor control in the fingers, but often with reduced dexterity. Surface temperature will be decreased.

Mild hypothermia will of course lead to more severe hypothermia shgould the swimmer continue to be immersed or unprotected. Hypothermia will eventually result for everyone in temperatures under twenty degree is they stay swimming long enough.

There are no great  concerns in recovering from mild hypothermia, just get dry and dressed quickly, following the usual procedure of dressing the torso and head first, and warming up with a walk. Do NOT vigorously dry the extremities even in mild hypothermia.

In diagnosing mild hypothermia, simply seeing if there is some chattering or shivering out of the water. In the water is more difficult, but the swimmer might have clenched jaws and have a minor difficulty speaking freely, or maybe report lesser claw-like symptoms in the hands (lessening on full hand motor control).

In the next article we’ll look at Moderate Hypothermia.

 Related articles:

How we FEEL cold water (loneswimmer.com)

Peripheral Vaso-constriction in pictures (loneswimmer.com)

Where did my CLAW go? (loneswimmer.com)

Extreme Cold Adaptation in Humans Part 1 (loneswimmer.com)

 

Cork Distance Week is coming but May gets in the way

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Cork Distance Week is coming.  The water is cold. (The water is always cold, relatively speaking). For the locals who know the conditions, Distance Week is still a very tough week. For many of those coming from abroad it will be even harder, maybe the toughest week’s swimming they have ever done. But to get to Distance Week for the locals, May stands in the way.

Though May is officially Summer, we tend to think of it as Spring here in Ireland. And it’s the toughest period of open water swimming of the year.

Why? Because the water is still relatively cool and conditions are extremely variable (at the start of May, 7.2° Celsius in Tramore, 10°C in Sandycove, with a two to three degree possible range). We can (and did) have frosts and days where the temperature was below the water temperature and for half of May this year at least the average air temperature was about ten degrees Celsius.  The Aspirants and others have to be putting in the mileage training. Constant cold winds and low air temperatures bleed the heat and resistance from the swimmers, building a cumulative effect of attrition. It’s the 23rd of May this year before temperatures got to 12° Celsius (53.7° Fahrenheit to be exact) and the day was actually warm (18° Celsius).

When the water is colder no-one is doing much more than hour and generally only the experienced distance swimmers will do that, but some of the less experienced will look at calendar and think the date is all is all they need to know.

And there’s the repetition, the grind of getting very cold day after day, when it’s acceptable for one or two days, the first couple of weeks of getting hypothermia  every day, thinking on nothing but swimming, eating, cold and heat is like a millstone, grinding swimmers down in a race between breakdown or crack up, and making it to the degree or two warmer waters at the end of the month. All the Sandycove Channel swimmers and Aspirants will make it because it’s what Sandycove swimmers do.

Lisa & Finbarr finishing a six-hour Sandycove swim at the start of May, in temperatures under 11°C. On this swim Fin and Lisa did their 100th laps of the year, Lisa joined the 500 laps group (“C”), Fin joined the 1000 laps group (“M”).

Someone will do something extravagant and push their exposure but it will only feel good for a day because Sandycove swimmers Lisa Cummins and Finbarr Hedderman, two of the world’s great cold water marathon swimmers, who have no publicity machines, will out-swim everyone in time and distance.

Lisa on her second Sandycove Island lap, when the rest of us were still arriving. Zoom to see her.

Feel good because you did an hour? Lisa had two done before you got started.

Feel great because you did four laps of Sandycove? Lisa and Fin did twelve.

Just swum your first double lap of the year? Fin already passed his hundredth for the year.

Finally joined the Centurions (100 lifetime laps)? Fin became a Millenarian (1000 laps). (Liz, what are we calling that one?)

Related articles:

Sandycove swimmers: Pressure to achieve (loneswimmer.com)

The Copper Coast: a Thrifty shore

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Powerstown head from the Guillamenes

Sea Thrift that is, Armaria maritima, also known as sea pinks.

First thrift of 2012

Ireland’s Copper Coast has a lot of it, growing all along the coast on the cliff edges, in rock crevices and stony ground where nothing else grows.

Growing on otherwise clear stony rockfall

It’s a perennial which has a high drought and salt tolerance, in fact it seems to do best in the driest, most exposed locations, especially along cliff edges.

Faded Thrift on clifftop above Kilfarassey

Older plants will grow larger clumps of leaves and roots.

On top of a rock spire at entry to Gararrus

It’s apparently highly copper tolerant, and flourishes along the Copper Coast, and in fact if the Copper Coast were to have an icon flower it would have to be the thrift, which displays a subtle range of colour from pink to mauve and purple from plant to plant.

Its season is early summer, so the coast is rampant with it at the moment, one of the signs of summer for a south-east open water swimmer, water reaching 10 degrees Celsius, and passing the thrift on the steps down to the Guillamene.

When I think of it, and therefore the photographs I take, are as I most commonly see it, silhouetted against the sea or the sky, framing events in the sea, or faded but still present during the winter, and always standing against the onshore Atlantic winds.

Thrift & Sheep Island, sea, sky and flowers.

When you can appreciate thrift in such extraordinary scenery, why would you want to trap it in a domestic garden?

Thrift against sea and canoes at Kilfarassey

It seems I’ve taken a lot of pictures of thrift (there are 98 tagged in my library so far and many more I still want to take, so you can image it was difficult to choose just a few), from early season buds, to summer blooms and late season stragglers to dead winter flowers.

Winter Guillamenes thrift

Apparently … I love sea thrift.

Understanding Rough Water: Force Three

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When writing the article on how to swim in rough water, I acknowledged that it’s an area I need to do a bit more about. And the popularity of the post caught me a bit by surprise, as it always does when such happens. But I wasn’t sure what I could do next. After all while I love writing about cold swimming, and it continues to provide me new avenues of investigation and expression, rough water is just rough water.

On last Saturday’s visit to the Guillamene, a swim I didn’t want to do, because two days previously I’d had a bad asthma attack while pool training, (for the first time in two years), and I didn’t feel I was recovered. Also, though the start of the fourth week of May, the water temperatures were still down, only nine degrees the previous weekend, worse the air temperature was low, only ten degrees, with a north-easterly wind. When you live at fifty-four degrees latitude, northerly winds are always cold. It felt just like winter and when I measured the temperature at the Guillamenes, it was on a par with the air temperature, ten degrees, yes a rise over the previous week, but with the chilly wind and the lowering dull grey sky and no-one around, it was less than inviting.

And as I said, the wind was north-easterly. As this point it’s useful to show you (again) how the Guillamene is situated.

Tramore Bay

The bay faces south-west (directly up is North in this image), the Guillamenes is on the west wide, so looking out from the platform you are facing south-east. It’s sheltered from the prevailing south-westerlies, but exposed to south-easterlies, easterlies and even north-easterlies.

The bay is just under five kilometres wide from Newtown Head to Powerstown head, a not-insignificant distance. Therefore a Force Three north-easterly wind will have about four kilometers of water to blow over before it reaches the Guillamenes. You may recall we discussed this in Understanding Waves for Swimmers a long time ago. The distance of water over which water blows is called the fetch. The greater the distance over water which wind blows, the greater the waves and chop that can be pushed up.

Apart from the fetch, the strength of the wind is important. I have long thought the ability to observationally measure wind using the Beaufort Scale should be an essential skill for serious open water swimmers.

Force Three on the Beaufort Scale is also known as a “gentle breeze”, a more pleasant title. Force Three is however a critical measurement for open water swimming because at Force Three scattered whitecaps start to appear, as crests start to crumble from the wind. This means an increase in rough water to the swimmer. (If you see choppy-ish water with no whitecaps, it’s Force Two). Below is a very boring picture of all these facts! A Force Three wind, blowing onshore, across a four kilometre fetch. It’s full size if you click on it and want a better look at what Force Three looks like, but it’s pretty unexciting. If you look around you’ll see those occasional whitecaps.

You can of course swim in Force Three, but you’ll be slowed down. It took me almost twenty-five minutes to pass the pier, where it would normally take twenty. I call Force Three critical because it’s the transitional point into rough water.

And because video is better for this, here’s a short clip. (With the wind blowing across the microphone, you might want to turn your volume down first).

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This second video is taken from the water. However, this was taken underneath Doneraile Head, and the fetch that wind was blowing across was less, so though the wind was the same, and blowing the same direction, the waves were less.

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Irish 10k Olympic Qualifier Chris Bryan 3rd in Euro 10k

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Irish open water swimmer and Olympic 10k qualifier Chris Bryan finished in a great third place at 1:54.14 in today’s Euro 10k Cup in Israel.

He placed behind Sergey Bolshakov (Russia), World Championship 2011 Bronze in 10km, who won in 1:54.04 and David Davies (Great Britain), 2008, 10km Olympic Silver, all according to Chris’ own Twitter account.

The water was a toasty 23 C with 6 laps of 1.6k. The field was 28 men from seven nations.

Euro 10k Cup course

Look forward to an upcoming Guest Article from Chris when he has time (which is rare), I don’t want to press him unnecessarily, but maybe this will serve as a gentle reminder!

His next and final target before London is another Euro Cup 10k in Portugal on June 7th.

HowTo: Swimming in rough water

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When talking to different open water swimmers one often find that they may highlight different skills and areas on which they believe it’s important to focus.

Since I’ve written a lot about cold, it’s a safe assumption (and correct) that subject is one of mine. But there’s another I don’t write about enough, parly because it’s not so amenable to written description, and that’s rough water swimming.

Rough water experience is essential to be able to deal with sudden changes in weather and water conditions. It makes for a well-rounded and adaptable open water swimmer, and I think skill in rough water is essential of ongoing safety.

For swimmers aiming for a serious target like an Ironman or first 5 or 10 k swim, I think one should train in as much rough water as you can tolerate, always being aware of the injury potential.

Rough water is a pretty broad description though that varies for the swimmer according to wind direction and swim direction.

Big swell with no wind will not produce rough water, where no swell and wind will. Rough water is a product of wind, usually onshore or cross-shore, and often caused by that much-disliked by open water swimmers phenomenon of wind-against-tide. Swimming into head-on wind is different to following wind and different again from cross wind.

Donal heading out into two metre swell and F2 onshore at the Guillamenes

  • Head-on wind and chop

Head-on chop is both tiring and potentially injurious and will slow you down. It will also affect the normal balance of a stroke making the stroke shorter. With asymmetric short period waves, there will no discernible pattern of waves to the swimmer. Sometimes having cleared one wave, you will crash immediately into another. Repeated impact across the head and shoulders can be the main problem. Also, the timing for sighting and breathing is changed.

More specifically, you need to learn to adjust your stroke. In head-on chop I drop my head lower than normal, and make a point of keeping low and maintaining rotation, difficult in the circumstances, to go partially under some of the chop and small wavelets, which minimizes the impacts. Other swimmers may have different techniques.

As with all open water, try to separate your breathing from your sighting. In head on chop, as soon as you sight, you may have a sudden wave directly in front of you. Try to time your sighting from the top of a wave.

  • Tail wind and following chop

In tail-chop (a following wind) I am most likely to swallow a mouthful of water. As I roll to breathe a wave can come from behind and swamp me. My solution to this is to focus more on my feet as an indicator of something coming, in essence an early warning system. Like radar but with feet!

I breathe bilaterally (every three strokes to each side). Therefore if I’m about to breathe and a wave arrives from behind, I’ll instead often not breathe and maximise usage of the wave for speed, taking little surfing bursts of speed if I can. This is also a reason hypoxic training is useful, to be able to adjust breathing timing or delay a breathe to account for changing circumstances.

  • Side chop and cross winds

Side-chop is the most difficult for many. Breathing into side-chop is a big problem leading to both swallowed and aspirated water. The only solution is to breathe to the other side. But even those of us who breathe bi-laterally will have a favoured side. I can’t maintain breathing on my left weaker side for a long period and not start to get tight in my shoulders, neck and biceps.  However water is rarely so rough that I can’t least maintain some kind of irregular bilateral breathing to relieve that strain.

  • Local effects

As with so many other aspects, there are often local effects to complicate things further.

In Tramore Bay onshore winds drive chop and waves along the side of the bay, whereas in Sandycove  onshore winds run directly into the outside of the island. The Guillamene is mostly deeper and it’s possible to swim further out, but behind Sandycove we swim closer in, choppy waves are reflected off the back of the island and the shallower bottom to make challenging water conditions. In Sandycove however the rough water is only a portion of a lap, whereas in Tramore Bay there’s no shelter from onshores and the bay also has a couple of spots where the water conditions changes, (passing the Colomene, outside Newtown Cove, and just inside Newtown head.

Not wishing to belabor the obvious or subdivide further, there are also diagonal winds and chop. A diagonal wind and chop direction can present even more problems as you may not see nor feel it arriving. The above are just ways of using experience to adjust to the situation. With practice and experience you will discover your own methods to minimise, where possible the difficulties of rough water, but it will still always be rough and therefore more tiring.

BTW, on an unrelated note, I’m not 100% about the new site layout. Any thoughts? Yea or nay? Options to adjust individual items I’d like to change from they are limited. Stay with it or go back to the last layout?

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Here’s another weird underwater creature for swim nightmare fuel

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What’s wrong with me that I like looking at all the scary things in the sea?

A few months ago, I collected some the related fears of open water, and suggested we use Megalohydrothalassophobia, as a name for the fear of underwater creatures. Here’s another one for the causal list.  The Cascade creature, aka deepstar enigmatica, or the Placental jellyfish, apparently though not rare, but only seen intact a few times. Checking around it seems like it’s about 50cm in diameter, and is usually a more common bell shape, but the turbulence from the submarine turns it inside out and give it that really creepy motion.

Anyone who’s ever had an unexpected encounter with a plastic bag while swimming will shudder at this one. Plastic bags are scarier than jellyfish.

More details/speculation on the creature here.

All the Megalohydrothalassophobia related articles:

List of open water fears (loneswimmer.com)

Anomalocaris. (loneswimmer.com)

Eel Shark. (loneswimmer.com) (My favourite)

Giant saltwater crocodile (loneswimmer.com)

Conger eels (loneswimmer.com)

Sea lice. (loneswimmer.com)

Now THAT’S a jellyfish. (loneswimmer.com)