28 Mar Hydration for Cyclists
Hydration is critical when cycling and exercising for many reasons. Core body temperatures rise during exercise and that rise is more pronounced when training and racing in hot climates. Evaporation (sweat) is the body’s very effective means of thermoregulation. However, the more fluid that is lost, the more an athlete’s performance can decline. Good hydration helps us tolerate hot conditions better and can help to prevent muscle cramping. Fundamentally, staying hydrated (by limiting the amount fluid loss that occurs when exercising), helps to keep an athlete’s body temperature from rising, and allows for better performance.
I always recommend that my athletes consume a minimum of one bottle or 500-750ml (25 fluid ounces) of fluid/hour. In very hot conditions, I recommend double that amount or up to 1.5 liters of fluid/hour. Of course, sweat rate differs among athletes so one easy method to assess your own is to weigh yourself before and after a training session or a race (and it may be worth doing this test in different temperatures and for sessions with different exercise intensities). If you weigh less after your session, you should hydrate more. If you weigh more than you did prior to your session, you may not need to intake as much fluid. Another telling sign is the colour of your urine. A darker colour is a sign of dehydration and an indication that you need to increase your fluid intake.
We also loose electrolytes when we sweat, mainly sodium. Replenishing lost electrolytes, therefore, is just as important as replenishing fluids. Rehydrating with water alone is insufficient. Not only does everyone sweat out a different amount of fluid (volume), but the amount of sodium (electrolyte concentrate) loss also varies. One simple test for sodium concentrate is to check your clothing after a training session or a race. If you notice a lot of white salty residue on your clothing, it’s likely you are a higher concentrate sweater. The exact amount of fluid and electrolytes loss for individuals can be determined in a lab setting but this testing is not always easily accessible. It’s important to note that the issue of sodium replacement is hotly debated. Anecdotally, the practice of doing so has worked well for me. For years I thought I was hydrating well until I got my sweat tested. I discovered that I am both a high volume (amount of fluid lost/hour) and a high concentrate (amount of sodium lost) sweater. I used to suffer from major leg muscle cramping in races until I started replenishing the correct amount of sodium for my body. As soon as I took in more sodium, my muscle cramping subsided!
Experimenting with different amounts of fluid and electrolyte intake in order to determine what is right for each individual cyclist/athlete may be needed.
Here is a general hydration guideline to start with:
Replenish with one 500-750ml bottle of fluid/hr. If the exercise duration is more than one hour or in hot conditions, include 300-1000mg of sodium/hr. My advice for electrolyte replenishment (which is based on my experience only as I am not a registered nutritionist), is to start with a small amount of sodium (~300mg/hour) during sessions over an hour and in hot conditions and if muscle cramping still occurs, increase the amount sodium ingested gradually to determine the right amount for you.
Stay on top of your hydration for a better, more enjoyable ride.