By no means. The average marching rate for foot-borne, pre-industrial armies has been a pretty consistent 10 miles a day. Only a few exceptionally well organized forces, like the Roman legions, could march more than that on a regular basis.

http://www.ibiblio.org/pub/academic/history/marshall/militar...

I think the Romans largely managed it through building level roads to march on. Most pre-industrial armies were marching off-road. I would be saying walking 2 miles/hour on a tarmac road would be someone's maximum before causing damage. Offroad I'd be saying 1.5, maybe even 1 mile/hour depending on the terrain.

In the late republic they were sustaining this pace in hostile territory -- where the roads were basically dirt winding along ridgetops and riverbeds.

Supposedly, the early US settlers (or maybe it was the conquering US army) utilized native American couriers that could run 30 miles a day like it was nothing. I've seen stats as high as 240 miles in 3 days!

I wish I had a link to the source (I'll dig it up when I have more time). I discovered this while researching "fox walking", the toe-first method of human locomotion that some believe is the natural means of human motion, before the advent of stiff-soled shoes. This skill appeared to become mostly lost in the indigenous populations after the Spanish introduced horses to the Americas.

A search on "native american" and "ultrarunning" should render some good links for those who are curious.

As an aside, as anyone who's ever read Stephen King's "The Long Walk" can attest, sustaining a 4mph walk is quite tough. I mean, who hasn't read that story and tried keeping that pace with GPS in hand?

There are Indian tribes in Mexico still running like this. Check out "Born To Run" by Christopher McDougall (excellent book by the way).

Not really, if you're forcing yourself to go faster you're likely doing damage. You might be able to go faster for shorter periods or slower for a lot longer. However, I would think if the Roman Legion had been doing 25km in 3 hours I doubt they would have won any wars.

Their forced marches were to make them march longer, not faster. I'm saying 2 miles/hour because the Romans only managed around 1.5 with weight.

My office is three miles from my house. If I walk at a slow, I-don't-want-to-go-to-this-meeting pace, I get to work in forty minutes. Same time for getting home. I did this for five years and I wasn't even in shape.

I'm not arguing that the Romans were slackers. Given the effort it takes to setup a Roman castra, the marching might be the least strenuous part of the soldier's day. Also, my daily walk is on paved sidewalk across mostly level ground, while the Romans often didn't have such advantages.

For an able bodied person walking through a shopping mall, three miles an hour is perfectly healthy and reasonable.