Learn Hardcore Japanese: takusan aruita ato ha nodo ga kawaku node, mazu hitokuti mizu wo nomimasu. - After walking a lot, I get thirsty, so first I take a sip of water.

Breakdown of takusan aruita ato wa nodo ga kawaku node, mazu hitokuchi mizu o nomimasu.

Why is it 歩いたあと and not 歩くあと?

Because あと meaning after is attached to the plain past form of a verb when you mean after doing something.

So:

Using 歩くあと would be incorrect here.

What is the role of は in あとは?

In 歩いたあとは, the は marks as for after walking a lot... and sets that time/situation as the topic.

So the sentence is structured a bit like:

This は often gives a general or habitual feeling, like the speaker is talking about what usually happens in that situation.

Compare:

The version with は sounds slightly more like a general statement or a personal routine.

Why is it のどが渇く and not のどを渇く?