What's "tension lines"?

[higurashi]

Hello,

My dictionary tells me two meanings of "tension line": lines on face, flow of current. However, either one of these does not make me to understand the sentence below. It is about the (computerized) hotel room in the future.


In-room exercise amenities using tension lines and doorknobs so that guests can de-stress whilte they get fit in the privacy of their own room.

reference

I do not know how "doorknobs" can unwind the quest.

Could someone help to understand the meaning of whole sentence?


Thank you,
Higurashi

[Anglika]

I think it means that the "exercise amenities" use tension lines [cords/wires that are tensed] that can be attached to the doorknobs in order that the guests can carry out exercises.

[Soup]

Here's a picture. This one's called a bodylastic, and in this picture it's attached to the top of the door, http://www.sport-thieme.com/y/450pixel/1487901.jpg

[BobK]

The doorknobs had better be well attached

b

[higurashi]

Thank you, everyone.

So it does not deal with electricity nor face muscle.

Soup-san,

Thank you for the picture.
I have never seen such thing in Japan!

Thank you!
Higurashi