Hydration and Cycling

We know that hydration is essential. Every cell, tissue, and organ use water. We joke that our bodies are 80% water.

Which isn’t that far off (we tend to be 55-65% water).

Studies have shown that an even 2% drop in our hydration levels translates into measurably lower performance. Once you hit 5%, your output can diminish by a much as 30%!

A 2% drop can occur from something as simple as spending 4-6 hours outside on a warm spring day without drinking. It doesn’t take much, and the brain fog starts to kick in.

Some studies point to our normal “thirst” levels kicking in at the 2% mark.  So if you are doing a cerebral task, it makes sense to push the water more and avoid getting thirsty.

How about a 5% level of dehydration? For a 150 pound man, that is 7.5 pounds or just less than a gallon (14, 8-ounce glasses of water, to be more precise).

Depending on how hot it is outside, you may reach those levels in as little as 90 minutes of working out. What’s worse is that this dehydration can shrink your brain, mimicking brain atrophy.

Whether you are a racer or a weekend warrior, water is critical.

Drinking Cold Water For Better Performance

A study  I stumbled across today takes hydration a step further and looks at the temperature of the water you are drinking.

For this study they had 45 men eat a digestible thermometer (the development of this thermometer is an interesting read if you are a nerd ). They could then measure their core temps at 15-minute intervals.

They then drank either cold or room temperature water and began a 60-minute workout (which included riding a bicycle to exhaustion).

The folks drinking the cold water had a 30-minute delay in any change in their core temperature. And they saw a .83-degree (Celsius) change in their core temps during the workout, whereas the Room Temperature drinkers saw a 1.13-degree increase.

The cool (pun intended) point is the performance gains. 51% of those who drank the cold water saw an increase in their time to exhaustion on the bike (an approximately 11-minute workout)

The study size was small, and there wasn’t a statistical increase, so the study has not received much attention.Furthermore, the duration of the cycling in the experiment was extremely short when compared to what most of us ride.

What we do know is that we perform worse in hot weather, in part because the body is “anticipating” that it may need more energy and begins conserving (gotta keep that heat pumping!).

So controlling your core temperature is key to unlocking your full potential.

Considering how easy it is to throw some ice cubes in your water bottle, it makes sense to gain every advantage you can.

How Much Water Should You Drink

Our water needs vary, and there doesn’t yet seem to be a consensus on how much water needs when cycling.

The liter per hour rule has been suggested for a long time and is the rough rule of thumb I use on days when I’m not inclined to drink (typically cold or overcast days).

A fascinating study from South Africa done in 2009, https://www.ncbi.nlm.nih.gov/pubmed/18853180 demonstrated that as long as you are drinking to satisfy your thirst, that may be sufficient. Cyclists who were forced to drink more did not see an improvement on their cycling over a 2-hour course.

The downside is that even the most hydrated cyclists lost about 2% of their power in this study. There’s just nothing you can do about that.

But if you can avoid those big power drops, you give yourself an advantage.

The key seems to be starting your workout in a hydrated state. And then keeping plenty of water handy so you can maintain that state.

I’ll carry two bottles on my bike and two in my jersey for a 2-hour road ride on a hot summer day. There is no reason to risk a lack of performance.

  • Water is essential to the body.
  • When we exercise we lose water.
  • Drinking water when working out keeps your power output high.
  • Throw some ice cubes in your bottles and see if you last longer.