Hydration is one of those areas that is often over looked especially on the longer distances, usually because it can be daunting and there is uncertainty on what to do. It isn’t however as complicated as you may first think.
When you run, you sweat, unless you are unique or have a very rare condition, it’s a fact and something that the body is designed to do. The more you sweat, the more your blood volume decreases, as you lose essential fluids. The more your blood volume decreases, the harder your heart has to work to deliver oxygen to your working muscles and as a result the harder your exercise becomes.
Sounds potentially dangerous, but it’s really not, it’s the body’s natural way of cooling you down. Runners almost never experience dehydration levels sufficient to cause major health consequences, but normal levels of dehydration will make you feel uncomfortable and cause you to slow down. This could be an issue for the mind as well as the body over the longer distances. If you want to get that top performance and elusive PB, then perhaps hydration may aid you in that, perhaps even more so than strapping lightweight shoes to your feet and shaving your body!!
Drinking while you run can help limit the negative effects of dehydration. But the questions that puts people off doing it are; what should I drink, how much, and when?
As we get better at understanding the body and how it performs, we have learned to tweak old practices to increase present performance. In the past, athletes were encouraged to drink as much as possible during exercise, or at the very least drink enough to completely offset dehydration (i.e. to drink enough to prevent any decrease in body weight during exercise). However, it is now understood that this is bad advice, for a couple of reasons.