Breathless with high pulse rate?

Hello all,

I am on Day 7 of my water fast. Today walking in the parking lot to go shopping, I noticed if I walked too quickly I get very winded and my heart rate shoots up. I'm not in horrible shape either! What's going on? I searched online but couldn't find anything useful.

Is this normal or should I be worried, does anyone else experience this?

Much appreciated!

Icy