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Cycling in the heat

Ever wondered how much you should be drinking when cycling, especially in hot conditions?

With temperatures measured on the road in the high 40s, stage one of the 2017 Tour Down Under from Unley to Lyndoch presented a real challenge to the riders and the Race Director. Wisely, the race was shortened to prevent disaster and to ensure that competitors were fit to ride on the following days.

With the coming of two of Victoria’s great cycling events – the Audax Alpine Classic and the 3 Peaks Ride – I feel the need to reflect on probably the most important pre-ride preparation we can perform: understanding our rate of sweat while exercising.

We need to sweat to maintain core body temperature and allow for muscular activity and brain function. Exercising, heat, and humidity all increase sweat production.

If we dehydrate, the muscle performance and cognitive functions are impaired, causing poor performance, headache, dizziness, nausea, and at worst disorientation and blackouts. As such riding for longer periods in the hills, in the heat, places the rider at significant risk.

The end of long days of hard riding in the heat are often the times when accidents happen, leading to trauma. In this circumstances, an ounce of prevention is worth a pound of cure!

Understanding your sweat rate can give you an invaluable guide to how much water you should consume while exercising.

You can estimate your sweat rate by doing the following test:

1. Weigh yourself without clothes, and with an empty bladder, as close to the start of exercise session as possible.

2. Perform your regular exercise session (performing the session in different heats and intensities will bear slightly different results, and therefore, it may be of benefit to do the test in varying conditions).

3. Keep the session relatively short – between 30 minutes and an hour – and don’t eat during the session.

4. Re-weigh yourself after your session.

5. Determine, in milliliters (ml), the amount of water you have consumed during the session.

The difference between the weight lost (grams) and the amount you have consumed, in milliliters, divided by the duration of the exercise in hours is your sweat rate; this is the amount of water you should consume during exercise. Increased temperature and exercise intensity should be accounted for appropriately.

It is important to highlight that you can drink too much – causing more frequent urination – and a situation which may be potentially fatal as increased voiding may occur and cause depletion of sodium, which is critical for cardiac function. For this reason, your drink bottle (or if you carry two, one of your drink bottles) should have an electrolyte solution.

Other practical tips for longer distances in the heat include:

1. Riding with a companion.

2. If you’re overheating, dehydrating or having cramps, dizziness, nausea, or difficulty concentrating: stop, rest, rehydrate and cool down.

3. Lying down in the shade with your feet elevated and a wet towel over your head can be very helpful.

4. ‘Pre-cooling’ to blunt rises in core body temperature when exercising in the heat and humidity. Consider using the strategy of using chilled / pre-frozen fluids both before and during the event.

5. Increased use of sports drinks coupled with regular carbohydrate-rich snacks to cater for increased energy demands from an elevated heart rate.

6. Take a tip from the Tour Down Under guys, shorten the ride and live to ride another day!

My final advice for riding long distances in the sun is to use a high-quality sports sunscreen and top up regularly!

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