Keep in mind - before heading into deeper waters, it's important that the basic technique is learned and can be performed alright.
Nordic Walking in rehabilitation
People with lower limb injuries (muscles, joints, ...) use the Double Pole action. That way the injured leg can be protected and supported by poles on either side (the poles work similar to crutches). During the healing process the injured leg can then take the full body load and he poles are planted with the fit leg. That way the injured leg gets more of a workout but the poles are still there to give support and security.
Nordic Walking for an increased cardio workout
The most obvious way to increase one's heart rate and cardio workout is taking up pace. If you're a walker you might start jogging or running. A Nordic Walker starts Nordic Jogging or Nordic Running. The technique has to be adpted in a way that the pole plant comes further forward (because the stride becomes longer). The emphasis is on the use of the arms (otherwise it's just jogging). With every pole plant the arms need to put pressure through the straps in order to have the acclaimed upper body workout.
Nordic Walking as a form of sports cross training
There are two different forms which have variations in themselves. One is Nordic Striding (this is the movement that is most similar to cross country skiing - where Nordic Walking derives from). With Nordic Striding the emphasis is on a long stride (jump). Have a look at the above photo.
And then there is Nordic Skating which is the ultimate workout (particularly when done uphill).
Skating mimics the technique cross country skiers use to get up a hill. Nordic Skaters stride (jump) from left to right in a forward motion. The poles can be planted simultaneously (both at the same time) or alternately (as in the basic technique: opposite arm leg movement).
As stated in the opening sentence - a basic Nordic Walking technique is necessary before venturing into Nordic Walking variations.
Nordic Academy runs instructor courses all around Australia on a regular basis to ensure proper and correct Nordic Walking is learned and taught. Once instructors have gained their experience and wish to offer more value to their clients, they can obtain qualification as a Nordic Walking Trainer (Nordic Walking Variations are part of the Trainer Course).
Yours in health