With backpacking, the best places to do it are far far from Houston, and the major issue is going uphill in thin air. So that's a very approximate correlation at best. I can run downhill easier than I can walk uphill, for example.

With a 10-lb load, you're not backpacking. That's a daypack. I've done dayhikes where I had more than 10 lbs of just water.

Anyway, I can ride 15 mph on level ground easier than I can hike uphill in Colorado, so the correlations are not altogether out of line.

Have you ever seen anyone walk at 55 steps per minute? I'm thinking even people using walkers beat that.