I often struggle with keeping adequately hydrated during my training and races. The effects of dehydration on running can derail your marathon efforts. Just like glycogen depletion, being too dehydrated will slow you down during the last few miles of a marathon. However, over-hydration is also a serious problem in endurance sports and can be just as counter-productive to your training. So where is the fine line of balance?
There is little argument that being dehydrated impairs performance and slows your recovery for the next workout. Therefore, you want to replace lost fluids as quickly as possible. But from my experience, it is very difficult to maintain a 1:1 ratio during a long run or marathon. During the summer months, even in an attempt to stay hydrated by downing a couple of liters during a run, I have lost as much as 8 pounds or almost 6% of my body weight. I’m not sure what the solution is in this case since I don’t think I could have digested any more fluids. As a result, I think that’s why I’m not a very good hot weather runner.
Some research I have read suggests dehydration isn’t all bad. When you become dehydrated from running, you provide a stimulus for your body to adapt to similar situations in the future by conserving more of what you drink after. This results in expansion of your blood volume, which is a positive adaptation. But this is only good to a point, maybe 2% or less of your body weight.
A loss of 2 to 3 percent of body weight during an endurance event is considered normal, which would be around 4 pounds for me. From experience, when I go beyond this point, I do begin to notice a significant increase in effort in order to maintain my pace.
As I mentioned earlier, over-hydration is also counterproductive and can even result in death. This condition is known as hyponatremia or “water intoxication”. So you’ll want to make sure you don’t drink to excess. To know if you are adequately hydrated before running, your urine will be clear – or a very pale yellow. If you are experiencing infrequent urination and the color of the urine is dark yellow, these are signs of dehydration. Other signs of dehydration are thirst, headache, constipation, fatigue, weakness, dizziness, irritability, cramps, depression, weight, gain, water retention, skin blemishes, vomiting or nausea, and bladder infections.
So how do you stay hydrated? I usually carry a water bottle with me all day and sip it every 10 or 20 minutes. Also, I only drink water, normally room temperature tap water. I rarely drink soda or juices since I’m not a fan of their high sugar content. During a long run I may drink something like Gatorade, but only when I’m running. In the mornings I usually have a cup of coffee, which is probably counterproductive to staying hydrated, but it is something I’m not willing to give up.