Beat The Heat (Part Two) – Marc Laithwaite

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Exercise in the heat can place a lot of strain upon your body, if you’re used to cooler climates. For this reason, many elite athletes will spend time acclimatising to the higher temperature. Acclimatisation can require up to 14 days, so what if you’re an amateur athlete traveling abroad for an endurance event, who can’t afford to travel 3 weeks before the event?

This is part 2 of our ‘exercise in the heat’ blog series. Last week we explained why exercise in the heat is such a problem (you can read by clicking the coaching articles link at the top of the page and then scrolling down through past blogs). In this week’s blog, I’ll explain how you can acclimatise before you travel and highlight the key physiological changes that take place, as a consequence of acclimatisation.

It’s a bit cold up North, so acclimatising might be difficult!!

Okay, if you live in the North of the UK and you’re traveling abroad to race, then you might be struggling to understand how you can possibly acclimatise. I use the term ‘North of UK’ as we all know that in the South of the UK, the temperature rarely drops below 18c. I’ve never traveled further South than Birmingham, but I hear they wear shorts and flip-flops pretty much year round.

In simple terms, to acclimatise before traveling, you need to make yourself hot and encourage sweating when you train. There are really easy ways to do this:

  1. Wear extra clothing
  2. Run on a treadmill or cycle indoors and turn up the heat
  3. Spend time in a sauna or steam room on a daily basis

I’d recommend you start doing this from 2 weeks out, but you need to do it consistently. Ideally it should be on a daily basis. There’s plenty of evidence to suggest that the above methods can help acclimatise you before travelling to warmer climates.

General guidelines:

  1. If you’re exercising outdoors, wearing extra clothing will lead to a higher sweat rate, so make sure you hydrate during the session. The same can be said for indoor running or cycling, make sure you are hydrating throughout.
  2. You should expect it to affect performance to some extent. If you use a power meter when cycling or you run at specific speeds on the treadmill, you should expect your power of speed to be a little lower than normal. If you’re temperature is higher, attempting to maintain the same intensity as usual could result in you being exhausted by the finish of the session!
  3. Try to progress the sessions in terms of exposure and intensity. For example, if you ride indoors, gradually turn up the temperature over a 7 day period and gradually build up the volume and intensity of the session. Don’t simply crank up the heat on day 1 and ride the full session as you’d expect to in cooler temperatures.
  4. The same rule applies for the sauna and steam room. Start with 10-15 minutes and gradually build your time to 30-45 minutes. Take a drink into the sauna or steam room with you to ensure you are hydrating adequately.

What are the physiological changes that take place?

There are a couple of key changes that take place when you are forced to sweat at a high rate:

The first is an expansion of plasma volume, this refers to an increase in the amount of blood plasma. Last week we explained that blood is made up of plasma (the fluid part) and cells. As you sweat, you lose plasma, which then thickens the blood. Part of the acclimatisation process in as increase in plasma, which means your blood is thinner. By increasing your plasma volume, this also means that you have more blood in general. The amount of cells doesn’t change, but the fluid component is increased, thereby increasing the overall blood volume. This is handy when your blood has to supply both muscles and skin, as discussed last week.

The second key change is a reduction in salt loss. Early in the acclimatisation process, your sweat contains a high amount of sodium. As the acclimatisation process progresses, your body retains sodium by reducing the amount lost in sweat. In simple terms, your sweat becomes less salty. If you’re acclimatising over a 2 week period, lick your skin every day and see if you can taste the change. It’s not socially acceptable to lick someone else’s skin.

As stated earlier, for these 2 changes to occur, you simply need to encourage a high sweat rate when training. The more you sweat, the more these changes will occur. Be sensible, reduce the intensity of the training session and gradually build up heat exposure over the 2 week period.

Until then, stay cool.

About Marc:

Sports Science lecturer for 10 years at St Helens HE College.

2004 established The Endurance Coach LTD sports science and coaching business. Worked with British Cycling as physiology support 2008-2008. Previous Triathlon England Regional Academy Head Coach, North West.

In 2006 established Epic Events Management LTD. Now one of the largest event companies in the NW, organising a range of triathlon, swimming and cycling events. EPIC EVENTS also encompasses Montane Trail 26 and Petzl Night Runner events.

In 2010 established Montane Lakeland 50 & 100 LTD. This has now become the UKs leading ultra distance trail running event.

In 2010 established The Endurance Store triathlon, trail running and open water swimming store. Based in Appley Bridge, Wigan, we are the North West’s community store, organising and supporting local athletes and local events.

Check out the endurance store HERE

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