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Heat chamber test

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Matt in the heat chamber

BBC News's Matt Davis is keeping a diary of his experiences of training for the Absa Cape Epic - a nine-day, 1,000km mountain-bike race in South Africa at the end of March 2008.

Read Matt's fifth diary entry
.

A major drawback of training through winter for an event in a hot country, is being unprepared for how you'll react to the heat. On the Epic, Sean and I will have to cope with high humidity, and temperatures of up to 40C. Not exactly what you get in Richmond park this time of year.

So to get an idea of what it will feel like riding in South Africa, I went to Kingston University's sports science lab and took the dreaded heat chamber test. Dr Ross Sherman set up an experiment to test how much I'm likely to sweat during the race - and how quickly my core body temperature will rise with the exertion.

The climate lab is in a non-descript, brick building at the back of the university. Inside, I had to strip to my boxers for an accurate measurement of my weight. Reclothed, Dr Ross took me into the heat chamber itself - a little whitewashed room not much more than seven foot square, with an exercise bike and a treadmill. He'd whacked the heat up to maximum - about 36C - and the difference between that and the outside air was stark. My starting temperature - measured with an in the ear thermometer) was about 36C. The plan was to cycle at a brisk pace and take new readings every 10 minutes.

I started sweating fairly quickly – a good sign of a healthy body’s response to the heat. Conversation was easy, and I was feeling good. It wasn't long before things started to get tougher, though. Outside on a bike, the airflow cools you down, but in the sauna-like conditions I was losing moisture pretty rapidly. I was managing to keep up some steady banter with Dr Ross, but my core temperature was increasing. After 10 minutes, it was up to 36.6C. Twenty minutes in it had hit 37.4C.

Once your "brain temperature" hits about 39C, your body will tell you it's time to slow dowm, Dr Ross explained. Also as you get hotter, your perception of time alters. He asked me to guage how long I'd been cycling. I said 40 minutes, but it was not even 30. Over a longer race, the differnce would be even greater - a good thing to know to help in the psychological battle with the long stages in South Africa. By the time I reached 45 minutes, my temperature ws 38.6C - more like 39C inside. Each minute was definitely a struggle.

My thoughts turned to the Epic - and the importance of staying out of the over-heating zone. We called an end to the test, and I was gagging for a glass of water. But first I had to weigh in again. The result: I was losing 1.31kgs in an hour - that's 1.31 litres of fluid. Not a bad result, according to Dr Ross. But more worrying was the rate at which my temperature had shot up.

Since my visit I've been taking a regular sauna on his advice, just to get used to the temperature. Hopefully, that will help me acclimatise faster, as I'm only arriving a couple of days before the race. Meanwhile, the organisers have just sent us updated profiles of each leg, showing the water points - one every 40 km or so. After the lessons of my heat test, I think I'm going to need a bigger Camelbak.

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posted Mar 20, 2008

I remember on my first Etape Du Tour (2006) the temperatures started in the low 30s celsius before hitting 42C or so by the time I got swept up by the broom wagon at the foot of Alpe D'Huez.

I also suffer from sweating like a leaky tap and having a core temperature that rises quickly. Staying hydrated is a real battle in the heat. At last year's Etape I went for the tactic of carrying an extra 500ml bidon in one of my pockets rather than armwarmers and gilet meaning that I was carrying a maximum of almost two litres when full. Perhaps might not be the same for MTB but I'm guessing you'll be going for the trusty method of a camelbak-type rucksack.

I think that hydration is one of those things that is often overlooked by those new to cycling and is one of the toughest things to discipline yourself to do properly.

Good luck though - it sounds like you are bang up for the challenge now.

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posted Mar 20, 2008

I have suffered from cramp in the past, often due to dehydration in high temperatures. Obviously electrolytes help prevent cramp. Energy drinks often have electrolytes in them but I would recommend taking a pure electrolyte drink regularly before, during and after each stage - perhaps 400 / 500 ml every two hours when riding. (They don't have much carbohydrate content so need supplementing). You can buy them in tablet form which you drop in water. I haven't suffered cramp / dehydration since using them even in hot conditions.

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posted Mar 20, 2008

You're right Alex - until I started cycling more often, and for longer, I never realised the importance of drinking and eating properly. Once it sinks in it's amazing how you come to see food and drink as fuel for your engine.

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posted Mar 20, 2008

The heat is one of the two things that concern me most about the race, and like yourselves, we're not flying out until next week (Tuesday evening) so acclimatisation won't be great. I'm hoping that a couple of extra bottles of fluid each day will get us through, but very interesting to hear the amount of liquid you were sweating out in the test. Did you get any information on replacing salts/other fluids to cope with the re-hydration?

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posted Mar 20, 2008

Matt, it was great to meet you and hopefully 'help' you a little before the Epic! I have a sneaky feeling, though, that your experience in the chamber was a bit of a rude awakening.

I hope you get loads of positive comments and maybe more advice on all aspects of training and preparation. Anyway, great article and all the best in the event itself - you're gonna need it!!!! winkeye

And when you're back, and if you need something similar again, give me a call.

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posted Mar 20, 2008

mad dogs and englishmen in the midday sun. Riding in temps like that can be quite unpleasant even if you are used to them. Remember to get water on your legs as this can reduce can reduce the chance of cramping. What i have done in simular situations is take ice from the drink coolers put it in my socks, helps prevent your feet from swelling, in my shorts both groin and thighs and then neck. Maybe even have something covering your neck and ears that you can soak regularly, foreign legion style. Oh, and electrolyte pills.

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posted Mar 20, 2008

A bit of a wake-up call for you Matt - but a great idea. Acclimatising to working in the heat will help you stay out of trouble. The Cape will be drier, so the sweat will evaporate rather than acumulate, and you may not realise how much you are losing. Don't get too bogged down trying to calculate how much energy / fluid / electrolytes to take in: trust your body - it's surprisingly well adapted to exertion in the heat. Aim to have a litre an hour on tap, and drink if you are thirsty. If you feel bloated, stop. Don't drink to cool down - pour water on your head instead. Urine output is a good guide to adequate hydration - drink more if you don't need to go every couple of hours. Electrolyte loss in sweat is low in the acclimatised, and you will easily replace this in normal eating after the race. Eat, or you will simply fall over after about three hours, all weak and shaky. And do take the sun seriously, if you haven't been warned already. If you burn on day one it will blight the rest of the week.

And have a fabulous time - I'm jealous! Looking forward to hearing how it all turns out.

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posted Mar 20, 2008

If anyone has read Michael Hutchinson's book on his training for the hour record, he also did some sessions in his blinding hot kitchen and turned on some other kitchen appliances to make it even hotter, apparently. I don't know what that did for him or his training, but if I remember correctly, he did mention that it is easier to ride in hotter temperatures than colder ones, so at least you've got that on your side winkeye good luck with it, think of all of us in the cold while you're out there.

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posted Mar 23, 2008

Thanks to everyone for the comments and advice - esp Dr Ross for watching me sweat (I think you enjoyed it a little too much, however). This time next week I'll either be nicely acclimatised to the heat and race conditions, or sitting in the broom wagon getting a lift back to the end of stage two. That day we have to do 140km and a 10km climb at the end... I think I must be nuts, although it seems there are a lot of other nutters out there too!

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