The importance of proper hydration when cycling

Drinking while cycling

There are few things as important as hydration. The need for water pervades every aspect of our lives. Yet when you exercise it becomes more important to keep watered. Forget marginal gains and enhanced performance, drinking enough liquid is about basic survival.

That may sound a little dramatic, but it is true. Depending on who you ask, we are made up of somewhere between 60 and 90% water. Any significant loss of that water can cause some serious physiological changes and not good ones. So maintaining good hydration is vital.

Effects of dehydration

Your body will tell you when you need water because you will become thirsty. The old adage that if you’re thirsty it is already too late has been proven false, but ignore thirst at your peril.

The physiological effects of dehydration are many, but include:

  • Thickening of the blood
  • Inability to sweat
  • Increased energy use
  • Decreased metabolic function

Thickening of the blood – Thicker blood flows slower and therefore cannot transport the energy and oxygen your muscles need to work effectively. It also forces your heart to work harder and not in a good way.

Inability to sweat – As we know, sweating is our body’s way of radiating heat generated by exercise. It needs to maintain a fairly low core temperature for optimum performance. If you can’t sweat, you overheat and then you can no longer continue exercising safely.

Increased energy use – Dehydration has been seen to increase the rate at which muscles burn glycogen. This has an obvious impact on how far you can go with your energy stores.

Decreased metabolic function – The gut needs water to digest. If you’re dehydrated, your body won’t be able to process gels or foods that would usually give you energy on a ride.

When to drink on the bike

Assuming you have usually good hydration in your daily life, drinking little and often is the key. Drink before you get thirsty and periodically throughout the ride. Nutritionists say every 15 minutes or so from the start of a ride but this isn’t always practical. However, try it and see if it works for you.

The thing to bear in mind is that drinking on the bike is like eating. You’re not doing it for that moment, you’re planning ahead. Keep drinking little and often and you’re ensuring your body has what it needs to perform throughout the ride.

What to drink on the bike

The best advice is to keep it as simple as possible. For anything under 90 minutes or an hour, plain water is the very best thing you can drink. Water is boring, so I tend to add squash to it for taste.

For longer rides, a mixture of water and an isotonic drink is ideal. The isotonic drink will replace electrolytes lost through sweat and deliver some carbs. Mixing it as a bottle of water and a bottle of isotonic drink will keep you hydrated and energised. Find an isotonic drink you can comfortably digest and stick with it.

How much to drink

How much you drink during a ride is subjective like just about everything else to do with cycling. A good rule of thumb is to drink at least 500ml per hour where practical.

If you want to know exactly how much fluid you need to maintain performance you’re going to have to do a sweat test. British Cycling recommends them to racers. Weigh yourself naked and note the exact weight. Go out on a 60 minute ride at race pace without eating or drinking anything.

Dry yourself off once you return and weigh yourself naked once more. The weight loss will roughly equate to fluid loss, less any food you had in your stomach at the time. Do this a few times and get a median reading. The loss in grams is now many millimetres you need to take on. So if you lose 700g in weight over that ride you will need to drink approximately 700ml.

Water is an essential ingredient in everything we do and cycling is no different. Drink to prevent thirst, not address it and you won’t go far wrong.


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