There is a trail runner I admire and sometimes see at Rancho, David Roche. It's pretty amazing to see him run because if it's really steep like the PG&E trail and he's going long like this 16-mile random workout, his pace slows all the way down to 6:08, although he's running 4-somethings downhill and 5-somethings on the flats. By virtue of winning the Way Too Cool 50K, he qualified for a trail run competition in Italy.
You would think guys like that wouldn't benefit from poles. But a whole lot of the top
Euro trail runners use them, all except Killian Jornet, perhaps the greatest of them. So it was strange to see Roche line up in Italy with so many other pole-wielding runners who looked like hikers to me. But he got thoroughly crushed by them, 96th place.
And at this year's prestigious UTMB 100 miler around Mt. Blanc in the Alps, most of them had poles except Jornet and even he got beat, first time ever I think, by a guy with poles. They seem to believe they can offload some of the work of hill climbs to their upper bodies, like cross-country skiers.