Riding in hot weather - avoiding dehydration
It always seems to happen. One week I'm riding around wishing I'd remembered to wear the heated waistcoat, then we get a few days of 'scorchio' weather. Riding a motorcycle in protective kit on a hot day sets up a unique combination of overheating and sweating, and a cooling and evaporating breeze. The body's physiological functions only work in a narrow range and if we get too hot or cold, we get disorientated or worse. So the body tries to maintain temperature of around 37 degrees by sweating. The result is a high risk of dehydration at the same time as we're struggling to stay cool. So what are the dangers of running short of body fluid?
Body fluid and electrolytes are vital to the function of the body's organs. If they are lost through sweating and if they are not replaced, we suffer dehydration. In the early stages, we get rapidly fatigued and start to lose concentration. In the later stages more serious confusion sets in, and the body's metabolic functions start to be affected. Not good. And that's why I send out a notice to riders to ensure that when they attend a Survival Skills advanced rider training course, that they pack some water.
So what are the symptoms of dehydration? A good sign that we are dehydrated is not "feeling thirsty", it's not needing to pee! That tells us kidney function is already shutting down to save fluids. By the time we do feel thirsty, with dry lips and a dry mouth, then we are already well into the early stages of dehydration.
Most UK riders are oblivious to just how real a problem this, even when riding at home in a British summer. In countries like Australia, New Zealand, South Africa and the US where they ride long distances in hot and dry conditions, they are much more aware of the risks. You'll also see racers taking on board fluids just before the start. But dehydration doesn't only happen to racers. Whilst we're not working physically so hard, we're often exposed to that cooling breeze for longer.
So what can we do to prevent dehydration?
Planning ahead is the answer. We can start by pre-loading with fluid before we go out. For sports like cycling and soccer, it's recommended that we drink around half a litre (roughly a pint) of fluid a couple of hours before we begin. Then around 15 minutes before setting off, aim to drink another half litre.
On the move, we need to keep replenishing fluids. It's easy enough to take a bottle of water with us, so we can take a drink when we stop. For sporting activities, it's recommended that we take around 100-150ml every 15 minutes or so when exercising - that would be around a half-litre bottle of water every hour. Given a particularly hot day, that's probably not far off what we should be drinking on a bike. I took a Hopp Rider Training day at Cadwell Park on a warm autumn day, and we were reminded to get some water on board before going on track, and regularly reminded to rehydrate between track sessions. Doing it right, we should be making regular loo stops too. If that's inconvenient, so be it. It's better than the side effects from dehydration.
Riding alone, we can stop when we like, but on a bike with a 250 mile tank range, don't wait till refuelling stops. Definitely make intermediate stops - remember, if you feel thirsty, you are already dehydrated. Group rides tend to go on too long, and we're all dependent on the leader deciding when to pull up. So if you're organising a group ride and you know it's going to be a hot day, then factor in short breaks at regular intervals, and try to get people to use the opportunity to top up - you don't want dehydrated and underperforming riders with you.
There's a lot of marketing surrounding isotonic fluids - these are basically water plus the electrolytes we lose in sweat, so they have the advantage of keeping the chemical balance of the body right. You'll find them in most service stations. Isotonic drinks also come in powder form - you can buy tubs of the stuff from any cycle shop and make up a couple of litres for the ride.
Personally I'm not fond of fizzy canned drinks because they are generally sweet and sticky. Coffee is generally considered a diuretic (ie it makes you pee more) but lately there's been some debate about whether the old advice to avoid caffeine-based drinks is actually correct, although it's generally accepted that the so-called energy drinks aren't good for rehydrating. Personally I prefer tea - it's not nearly so strong a diuretic and I like it!
However, they all cost a lot more than plain tap water!
So what to carry fluids in? I avoid buying plastic bottled water, partly because the plastic is liable to split when wedged into a pannier or under an elastic strap, and partly for environmental reasons. Any cycle shop will sell you a plastic water bottle - they are (just about) unbreakable and will squash - or an aluminium bottle. A little more cash will get you an insulated plastic cycle bottle or a Camelbak which is a plastic bladder that sits in a backpack harness - fill either with ice cubes in it, top up with water and even on a hot day, you'll have something cool to drink for a hour or so.
A couple of final warnings. Steer well clear of alcohol. It might be tempting to sink a nice cold pint "because I'll be well under the limit" but if you're rehydrating, the alcohol will be absorbed faster and be even more disorientating than normal.
And... DON'T drink ice-cold water. The thermal shock of pouring ice-cold fluids into the stomach fools the body into thinking it needs to shut down the sweating mechanism. That's definitely not what we want.
Kevin Williams
Survival Skills Rider Training...because it's a jungle out there
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