I don't do "Nordic Walking" exactly. However, I do like to use a single trekking pole when I hike. Many of our local hikes are on steep and rough trails. (Indeed, calling some of them "trails" is stretching it!) I find by using one pole it is easier to maintain balance. On rough ground you expend a lot of energy just keeping and/or recovering balance, especially when coming down. A pole is also handy for balance when stepping from rock to rock to cross a stream.

I seem to get most of the benefit from one pole, and that keeps my other hand free. I like the adjustable poles, since I can change the length to suit the terrain, and when on flat easy ground I can collapse the pole and attach it to my pack. I personally don't see any benefit in the shock absorber models.

I find by using a pole, at the end of the hike I am less fatigued and my aging knees feel better.

I am also a single pole user, and I find one increasingly useful as me and my knees age. I like my adjustable pole for tricky balance situations and also for rattlesnake situations, especially for thick brush. I extend the pole to full length and let it take the point, as I slow down so that the pole can strike up an acquaintance with Mr. Snake....

Why doesn't someone do a poll on pole use?

Ditto for using a single pole when hiking for all the reasons mentioned.

An update;

I got these poles:

http://casualadventuresgoa.mwrc.net/en/product.php?product_id=55915 (no affiliation),
and have given them a try---seems like they are exactly what I want/need.

I also (finally) found a "local" (if 40+ miles away is local) source for some follow-up training to my 1 hour introduction.

Nordic walking looks simple, but that is not the same as easy (you need to get the form right), at least for me. But when I do it right, I feel a real pick up in speed and the cardio work out ramps up, without the pounding of jogging (my knees say thank you). Exactly what I want and need; my Doctor is of the opinion that starting my heart beating at least once a day is good for my health.

Ditto+ for all the same reasons mentioned!

My wife and I took about a 3 mile, hilly, 45 min., Power Walk this afternoon. The weather was almost perfect, albeit a little too warm. I carried one of my several, short (~34"), crookneck hickory walking sticks, It helps with my gamey knees & back, especially on the steep up and downhill portions. There is definitely a bit of a Victorian feel to perambulating with a walking stick. But, I've reached an age where it blends nicely with my white beard and dark hair.

I usually walk with one old-fashioned, hiking staff--good for balance on loose stone, and for fending off dogs.
I think one stick forces a person to walk slower, the side benefit of which is that the person takes in more of the view, etc...