Is running a more efficient way to travel than walking?

From my experience of roughly analysing this a couple of years ago when I was losing quite a lot of weight, I drew two main conclusions:

* Calories used is a function of total distance travelled and your weight, your speed isn't really that significant a factor.

* Walking rather than running uses about 80% of the calories for the same distance compared to running. It seems to be based on the mechanics of changing gait. If you at walking speed (google MAF - maximum aerobic fitness for more info), you use more calories than just walking.

While these would seem to be opposite to the conclusions in the article, it's worth noting that the MET value is a function of calories over time, not calories over distance. The faster you're moving, the more calories you're using and the greater the distance you're covering, and they roughly cancel out.

I also found it interesting that running slowly and/or walking is better for losing weight as running faster primarily uses glycogen (and makes you hungry), and running slowly primarily uses fat. This doesn't really affect energy efficiency, per se, but fat is a more efficient energy storage source, so this might be relevant in answering the posed question. But in any case, if you want to lose weight, walking is significantly more useful than running as you can generally sustain the activity over a longer period of time, and with less stress on your body.

That's a fancy way of saying "around 5%".

That gives you a hair over 13 min time on a 3000m run. When I was in the (Norwegian) military, that time would get you a 7 out of 9 score for males, and 8 (or 9) out of 9 score for females on a physical test. Pretty solid score.

It would also almost give you a sub 3 hour marathon.

You'd be a pretty capable runner if you can keep a steady 7 min mile, for the sake of running efficiently!

7 min mile sustained feels like an impossible goal.

Hell, my best single mile is 6:48 and I'm dead at the end of that.

The general principle is that you stay in the metabolic range where you're primarily burning fat reserves rather than using glycogen. The body typically has sufficient reserves for about 30 minutes of maximum glycogen use. The faster you run, the more glycogen you're using compared to fat, and so the quicker you'll run out and hit the wall.

A lot of people don't get on with MAF because it forces you to stop running and walk a lot in the early stages (essentially, you have a target HR of 180-age and if your HR is above that, you switch to walking), and even when your body does adapt and you can keep running all the time, you have to run much, much slower than you think you're capable of and that you probably want to be running at. But, over time you'll find your body gets more efficient and your speed at the target HR goes up over time. But to translate it into normal terminologoy, it's like you're always training in zone 2, although for most people 180-age is lower than the calculated top of zone 2.

An anecdotal result is that I used to be exhausted at the end of a 5km because I was running as fast as I could. Within a few weeks of switching to MAF training, I was routinely doing 10km-15km without really feeling tired and within a month I'd accidentally done a half marathon (very slowly, of course) after getting lost and being stuck on the wrong side of the river for 4km longer than I planned, and then an extra 3km the other side. I was tired at the end of that, but I also never would have believed I was even capable of that distance a month earlier.