New mixed run results throw a wrench in the works for my research

I had previously talked quite a bit about how it doesn't matter how fast you do a certain distance, doing that distance will burn the same amount of calories regardless. Up until this point all the information I was gathering seemed to be confirming that. But then the other day I did another "mixed run" where when I feel like it I slow down to a walk to catch my breath without any sort of focus on when I do so.

I went about the same distance and was moving for about the same amount of time yet got strange results that are different that what I have seen up to this point.

I tried to keep as much of the stuff the same on each of these runs such as where I am going and how far, but I don't have a regimented break time for walking. The last time I tried this same thing I went 6.8km in 53 minutes and burned 411 active calories. As you can see above I burned significantly more on this run even though it was only 800 meters longer and took just 5 minutes longer.

I'm digging through the data looking for what I might have done differently to result in such a disparity but I can't find it.

In the slightly shorter run I did the day before my heart rate was consistent with this run as well as I averaged 142bpm with a max of 166. It's also almost exactly the same.

This doesn't shed much light on the situation either. That last km I was standing at stretching and therefore the time for that last km is actually a lot longer than it was. But if anything, that should have resulted in me burning FEWER calories, not more... right?

I guess this is kind of proof that actual scientists are never truly "finished" researching what they are working on because after 4 trials of all the same results I though I had this all figured out. I am still at a loss as to what could have possibly happened to make this very similar exercise session burn 160 calories more than the last one.

I'll do another one today and see what happens. I think I could be heading back to the ol' drawing board with this even though there are real studies out there that show that running and walking burn the same amount. This isn't just some sort of hair-brained idea that I dreamed up on my own.

Take this

for example which is entitled "Walking can burn more calories than running"

Then though, there is also another less-scholarly

I am not interested in determining a definitive answer for everyone though and really believe that results will vary. This is why I am conducting the experiment solely using myself as the test subject.

If you have any results handy that show your caloric burn as well as the time per km and you don't mind reposting it in the comments section, it would be appreciated.