Here's the takeaway for 1600m at 86m/min or 160m/min:
- EE during exercise was 372.54 ± 78.16 kilojoules for the walk and 471.03 ± 100.67 kilojoules for the run. Total EE including excess postexercise EE was 463.34 ± 80.38 kilojoules and 664.00 ± 149.66 kilojoules for the walk and run, respectively.
So you burn about 30% more calories by running the same distance at just under twice walking speed.
...for the first ten minutes. I'm not up on my exercise science but speaking from personal experience, my circulation isn't even properly going for the first mile. The runners were also done in ten minutes, while the walkers were done in 20... so if you're comparing time instead of distance, the runners are burning 160% more calories.
If your circulation isn't even properly going for the first mile, then I don't think you are of average fitness you are definitely of above average fitness. After the first mile I'm in a ditch crying asking myself why I even tried to do that. I'm not overweight, am not really super weak or super strong, but my heart is definitely a bit weak as is most people who are of average fitness.
Well, put it this way. I used to run in Southern California. Now I run in Seattle. Which means it's 35 degrees and I'm in shorts and a t-shirt. For the first mile and a half I resolve to fix this because my hands are freezing and I ache like a sonofabitch. Then about a mile and a half into it, my hands are warm, I'm limber and I'm good for at least another couple miles before I start to get tuckered out (depends on a number of factors). I can't really remember a time it wasn't like that, at least once I was running regularly. I've never considered myself to be of "above average" fitness; to the contrary, I've got maybe a 4" vertical leap and can't bench worth a shit. But if you're having a rough time running a mile, get running more! It's good for you. 
Being able to jump and also benching a certain amount of weight isn't fitness either, though. Both are anaerobic exercise. I would argue that you are probably of above average fitness aerobically, but at average or below anaerobically. I doubt many people who can run in races are necessarily good a benching. In fact, most of the people I remember from school who were in track and field were pretty weak, yet were extremely physically fit. I also know people who go to the gym all the time and work on muscle tone who couldn't run a couple of blocks. I guess I'm trying to differentiate between aerobic heart fitness and anaerobic strength fitness here. Most people have weaker aerobic fitness.
Yep. Have you seen Olympian distance runners? They look anorexic. But it makes sense. Less muscle mass using up less oxygen in the bloodstream so as to more easily sustain aerobic activity for longer periods of time. The body optimizes itself for the activities we train it to. The style of training I prefer is High Intensity Interval Training (HIIT). It's a decent enough cardio workout that simultaneously builds muscle mass, packed into a fairly short amount of time. Kinda like crossfit, minus the stupid.
Hell yeah, running in 35 degree weather here is much better than other places. Just did 3 and a third last night and after you warm up (about a mile for me) it becomes significantly easier from there, hills notwithstanding. NW running is great.
In my snooty elitist young-and-still-uninjured opinion, anyone "healthy" is able to run one mile (non-stop). I don't care how fast you run it. If you can't run one mile non-stop, you aren't in good physical condition. Humans were made to run. We evolved to run slow and long. If you cannot do what your body, over centuries of evolution, became designed to do, then there is a problem. That being said, I think a mile is a big mental barrier for people. I think a lot of people are physically capable of doing it but mentally do not believe they can. And if you don't think you can do it, you're much more likely to give up halfway through than to make yourself push the whole way. Screw walking. Anyone can walk. Everyone should be able to walk long distances, no problem. Walking is a basic requirement. Hell, it's a fucking prerequisite for existence. Running takes a little work and some discomfort. But that is about all. That, and enough stubborn-ness to push past your mental blocks. If you are physically incapable of running one mile, something is wrong with your health. Health At Any Size - sure. If you can run one.
That's kind of the point I'm trying to make, actually. Being of 'average' fitness doesn't make you 'healthy'. Average fitness can mean you don't exercise often, but you do exercise occasionally. If you have a flat stomach at 30 or can easily run 10 miles then you are not of average fitness, you are above average. Being 'healthy' or 'fit' is not 'average fitness' in my view. That being said, you could be right and it might have to do with age or even culture/location how people view fitness and health. It's also possible that if you are around people that exercise often or if you exercise enough that you have seen drastic change in your fitness that you could be blinded by the long period of time of being at where you are, and not quite remember or not quite realize that people on average are actually where you were at probably only 2-4 weeks into serious exercise and stagnate there for long periods of time without progress. As an aside, a lot of people equate weight to health as well, too. I was told by a doctor recently after I said that I was going to start exercising more that "Oh you look pretty good, though". I know for a fact that I'm not physically fit, and would probably be called "average", but since I eat well I tend to look healthy when you look at me with a shirt on.In my snooty elitist young-and-still-uninjured opinion, anyone "healthy" is able to run one mile (non-stop). I don't care how fast you run it. If you can't run one mile non-stop, you aren't in good physical condition.
If you are physically incapable of running one mile, something is wrong with your health. Health At Any Size - sure. If you can run one.
I carefully caveated for a number of factors, actually, with "healthy": anyone recovering from an injury, ill, or otherwise excusably unable to be fit is inherently discluded from the group I'm saying should be able to run a mile. Likewise, pregnant mothers who have to be on bed rest. If you have to be on bed rest, you're clearly not healthy, and so on. The average has absolutely nothing to do with the ideal or even the minimally acceptable standard. The average is simply a metric to represent the mid-grade of the current population, approximately. I would not want to be an American of average fitness; I imagine it would be equal to approximately no fitness. The average American woman is over twice my size. I would not find that an acceptable size to be, personally. And I don't think other people should simply because it so happens that it's the mean. I don't think we are necessarily disagreeing. I will say I think culture and location are probably significant factors in what the average or minimum standard of health are. French women don't get fat, and so on. I believe that humans are meant to run. It is that belief which drives my conviction that all healthy people should be able to run a mile non-stop, and my suspicion that if you cannot - hell I will be generous and even say you have a week or ten days in which to build up to an attempt - you are simply not healthy. This generally flies in the face of the Health at Any Size movement, which I don't usually go out of my way to disagree with - but obese, sedentary people (or obese people who are able to "walk long distances without being short of breath" - often populate the HAES movement, even using the above quote as a demonstration of health, when I consider it a requirement for life and not an acceptable baseline for health or fitness. I think being able to run a mile non-stop should be the bare minimum standard for anyone to claim they are fit or healthy. I don't even care what you weigh, to pull in your last point. If you are 250 pounds and can run a mile non-stop, I am willing to say you are healthy. But if you can't, I'm not. And god, if you're running a mile non-stop, at least you're trying. Being able to walk long distances is not trying.