I'm a sport scientist, so this thread caught my attention, and perhaps I can provide some insight:
Q: Trekking poles increasing energy expenditure?
Yes, in the purest sense. This likely seems absurd to every hunter who has felt that they spare the body, and spare 'physiological stress'. The nuance is that (as was pointed out in the thread) the increased arm activity of the motion does account for higher ventilation and heart rate (from this you can then estimate caloric expenditure, which is going to be higher).
However, I sifted through 4-5 journal studies comparing conditions, and didn't find one that also showed an increase in a measure we call RPE, which is your perception of exertion. So the feeling of fatigue is not being generally found to be higher despite a calorie increase (which is inferred/calculated from the energy expenditure). In fact, when comparing only incline conditions, I found two well designed studies that observed significantly lower RPE and a trivial reduction in energy expenditure for going up. So in the studies that found increased energy expenditure, actual trekkers didn't report and increase in perception of effort.
What we also must bear in mind that most studies, to provide adequate controls (think reduce noise to hone in on a signal), compare with and without poles on a set pace. So it is not entirely clear whether the additional 'cost' of using your arms is a great tradeoff because hiking at higher speeds (which could negate the acutely increased expenditure because you would be done sooner, and on top glassing or at the truck unpacking).
Importantly, I found two studies that demonstrated meaningful reductions in stresses that are unrelated or not directly related to calories or 'metabolic stress' when using trekking poles. In our field we would call these neuromuscular stresses. One study showed important reductions in lower limb stress (measured by movement at the joint from ground impact...think of it as 'how much did the foot get banged up with each step'?). Another study found that muscle STRENGTH after hiking activity was higher in the with pole condition compared to without. They also reported higher perceived soreness in the non pole condition compared to the with pole condition, and a higher CK level when not using poles (CK is an indicator of muscle damage/muscle stress) .
OK, enough science, my 'anecdotal':
-I go uphill faster with poles. I notice this on scouting missions.
-If I don't use poles with a heavy pack, I end up spending a lot of energy stumbling around. That extra point of contact helps alot.
-I'm way, way less sore in the muscle, but also my old sporting injuries are less flared up, when i use poles.
-Poles have other uses when you hunt: balance your bions on them to increase stability if you don't have a bino pole, enhance your tarp set up or use with a single wall tent or your hammock tarp.
Gear.