Because you are not doing as many miles during your
taper period that you are not drinking as much water
as you were when you were training to your full
potential.
The impact this has is that your body does not
remain as hydrated as it should be. Having your
body fully hydrated will improve your marathon
performance and reduce your chances of hitting
the wall in the later stages of your marathon race.
It is for this reason that you should remain
conscious of fully hydrating your body during the
taper period even if you don’t feel the need to
drink as much water as you previously did.
Ideally you should aim to drink at least 8 glasses
of water during the taper period in order to keep
your body fully hydrated and therefore in peak
physical condition for your marathon race.
I am off to prepare for the run on Sunday. I will post after the run.