Dehydration can be defined as the excessive loss of body fluid.
There are 3 types of dehydration:
1. Hypotonic - the loss of electrolytes, in particular sodium
2. Hypertonic - primarily the loss of water.
3. Isotonic - equal loss of water and electrolytes.
Cyclists can experience dehydration very quickly and I'm not talking about elite cyclists here. I am a recreational cyclists living in Brisbane, Queensland. I ride regularly and in all seasons and I have had the unfortunate experience of dehydration.
It was a very hot and humid February day. The ride consisted of both on road and bike paths and the duration of the ride was approximately two hours. The only stop of any duration was for a coffee break and during the entire ride I only consumed about 600ml of water and the cup of coffee. I was feeling fine and riding well and was not feeling at all thirsty until about two thirds into the ride when I had to negotiate a rather steep but short climb. Three quarters of the way up the hill, I felt that I couldn't pedal any further. I had hit a brick wall and was forced to walk the rest of the way to the top.
On reaching the top, I felt light headed and had trouble keeping my eyes focused. I didn't say anything to my friend, got on my bike and continued riding until we reached our vehicle. Whilst my friend secured the bikes on his vehicle, I became increasingly nauseated and lost all colour vision. Everything became grey, the sky, vehicles, trees and people.
It wasn't until we had arrived back at my friend's house, unloaded the bikes and consumed a couple of beers that I started to recover, some 2 hours after I first felt unwell.
I saw my doctor (also a cyclist) the next day, who, after a few questions suggested it was probably dehydration but sent me off for a blood test to check the level of my electrolytes. The test results confirmed his diagnosis which prompted a lecture on the pitfalls of not consuming sufficient liquids, particularly in such hot, humid conditions and that beer was probably not the best way of hydrating the body.
The doctor suggested drinking a litre of water regularly during each hour of exercise plus replenishing lost electrolytes with Gatorade Endurance or something similar. Being a good patient, I have adhered to his advice and am happy to say that I have not experienced a similar problem since.
Even if you don't feel thirsty, it is wise to have a frequent intake of water.
Signs of dehydration include headache, being dizzy and lightheaded, irritability, producing less urine, which is much darker in colour than normal, dry mouth and fatigue.
On the lighter side......... A pedestrian stepped off the pavement onto the road without looking and gets flattened by a passing cyclist.
"You were really lucky there"said the cyclist.
"What are you on about, that really hurt!" said the pedestrian as he lay on the roadway rubbing his head.
"Well, usually I drive a bus" replied the cyclist.
Keep peddling and stay hydrated.