basshead81 got here first.....what he said.
My reply below:
No telling as it's going depend on the output capabilities of the subwoofer, the size of the small room, sound wave interaction with a room's acoustics and how this will impact measurements at the main listening position.
(forgive me for leaving any pertinent factors out of my above)
It really isn't allowing the sub to dig deeper. What's happening, it's making what the sub has to offer, more noticeable by raising the SPL at lower frequencies. A sort of free lunch if you will known as cabin gain.
If working with a subwoofer who's specification are 35Hz, my recommendation would be to upgrade the subwoofer as opposed to hoping to get more out it by placing it in a small sealed room.
What subwoofer are you working with?