A team of pathophysiologists at the University of Milan has found that climbing stairs or walking for short bursts allows people to consume 20% to 60% more energy than if they do the same activity nonstop for the same distance. In their study, published in the Proceedings of the Royal Society B, the group asked volunteers to walk on a treadmill or climb stairs while also monitoring their oxygen intake.
Treadmill walking isn’t real walking.
Was it a treadmill stair climber as well?
How is it not walking?
There are certainly trade-offs, certainly if you have the option of walking in a diverse real location that would be better than a treadmill.
Different terrain, different elevations, not the same repetitive motion over and over again.
3 miles in a treadmill does not feel like 3 miles on a track or park.
Try it yourself. There’s different muscles in my feet that get tired. I’m sure a treadmill is better than no training at all, but if you are aiming for a 5k try to do real walking or running.