Mark, you hit the nail on the head. I believe this Nordic Walking is similar to so-called Power Walking. Exaggerated arm movements and elevation of at least the hands (and the weights/poles) in them at or especially above heart level is key to achieving the 20% increase.
This is fine if cardio benefit is the desired end of such exercise. For the hiker, this often, but not always, is NOT the goal. Hence we use poles of the proper length for our height (whether they be adjustable or fixed-length matters not) and don’t do exaggerated arm movements which elevate the hands above the level of the heart and certainly NOT to shoulder level.
This is NOT to say that there is no increase in overall effort, but it’s certainly NOT 20%, IME. I’m sure that a hiker using poles IS doing more work – we have to be, we’re lifting something even if it’s only 2.7oz GG LightTrek poles (not to mention the weight of our arms and hands). There’s no getting around this fact, viz. MORE WORK IS BEING DONE, hence more energy is required, hence more calories consumed.
I often wear a Polar HRM on near daily fitness hikes (still use GG poles of the proper length and before that Leki poles adjusted properly for length) and I can tell you from empirical observation on myriads of occasions over several years that proper form when using of trekking poles adjusted to the proper length to keep the hands at or below heart level when traversing level ground DOES NOT PRODUCE A 20% INCREASE IN MY HR, or even a 10% INCREASE can I ever recall seeing on the receiving unit versus not using any poles. The time I’ve really noticed an increase in HR with trekking poles is that it’s so much easier to “trek on” that I’m hiking faster, hence my rate of energy expenditure increase and my HR rises.
Psychology sure plays a part. Everyone knows that athletic performance is less if one is very depressed. I was once running on the treadmill in my basement, pushing myself near the end of my workout and was listening to music. I was exhausted and ready to cut short the finishing half-mile “sprint” (take that term with a grain of salt), when the theme from “Chariots of Fire” came on. My whole mental attitude changed and I lost all sense of fatigue. I even kicked the speed up ~0.5mph partway through. My daughter runs marathons and uses that Theme-song during training runs when her legs feel like “Lead” and her mind is weakening (it gets hot in Los Angeles where she lives)
Pumping blood above the level of the heart is hard work. Why do we often lower the head (lay them down vs. sit them up) of an individual in certain medical emergencies?!! We know why.
Try this one out: Step-aerobics – a simple 4″ to 8″ step. Hold some 2-5lb weights in each hand hanging down at the side. Step up and down slowly for several minutes – whatever it takes to get a fairly stable elevated HR. Then step up and down with 2lb weights (or 5lb weights if you want) in each hand and do alternating shoulder presses (the arms and weights are above heart level – don’t lower them, i.e. arms and weights below shoulder for the entire period) for somewhere between 2 and 6 minutes. Note the HR. Then, without resting switch to alternating bicep curls (the weights and hands are below heart level). Note the HR. Even though exercise is continuing, the HR will drop simply because the arms and weights are below heart level.
Ok. This is a more exaggerated example than the Nordic/POWER trekking pole walking, but it’s only to illustrate the point. To hold the HR down and the work required to be performed down, keep the hands at or below heart level. I truly do not believe a 20% exertion increase will result if this is done. Some, yes, and I don’t know what that percent increase is, but it won’t be 20%.
If anyone feels I’m wrong, please correct me AND tell me WHY so that I can understand my misinterpretationof what I’ve observed during my workouts and hikes.

