Does 2 two mile jogs = 1 four mile jog?

Yes the longer run is harder - feels harder - but still burning the same if same pace, and your weight is probably the same.

HR will likely be higher for that same reason because it feels harder - and that's exactly what a HRM would show you.

Of course, HRM for calorie count would also say you burned more in second half with higher HR - even though that is NOT true.

It's like - does the first set of squats at X weight feel easier or harder than the second set at same weight?

2nd set usually harder, because muscles are tired.

Same with run - when you divide it up, you get recovery.

Use this for calorie count - more accurate than HRM actually.
http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

The Gross option is what HRM or database or treadmill would report. For what you want to log and eat back so you keep a hopefully reasonable deficit, use the NET option.

If your objective is to burn more calories, then I believe 2 two mile jogs are better due to the after-burn effect. I recommend the following article from Runners World (http://www.runnersworld.com/weight-loss/running-v-walking-how-many-calories-will-you-burn.) It probably doesn't make a big difference though.

Also, I have been running for many years--enough that my average pace has had to slow substantially. And in my opinion, an 8:53 per mile pace (4.5 mile in 40 minutes) is as fast or faster than your average runner. That pace may not win you any races, but it is nothing to be ashamed of.

A mile is roughly 100 calories burned regardless of speed or how many you do back to back.

In fact, I had a coach awhile back that suggested that I break long runs into smaller chunks like this whilst running for weightloss and ramping up for a half marathon that I really didn't care if I did all that fast. There was a bunch of talk about glycogen stores and burning fat vs. muscle... but I don't remember all of the details, I just remember he said it was better for me to do three 45 minute runs spread through the day rather than one 2.25 hour run because more fat vs muscle would burn off.

The pace of that mile makes a difference. But agreed it's the same in chunks or at once.
http://www.exrx.net/Aerobic/WalkCalExp.html


So you and others will understand what was being suggested and why.

It takes about 30 min of exercise for the body to slip in to the final ratio of energy source for carbs:fat (unless going over anaerobic threshold, always burning some ratio).
Prior to that, higher carb%.

There is limited carb stores, and while in a diet, body doesn't even top off what it would like to (hence fast water weight gain when eating at maintenance).

After about 90 min of average intensity exercise (shorter if you go harder), your liver carb store are getting low, but blood sugar must still be maintained, so amino acids are converted to glucose. Amino acids from muscle breakdown that is happening somewhere, or leftover from last meal.

After anywhere from 2-4 hrs the muscle glucose stores have now been used up too (the wall, or bonk in cycling) if too fast a pace, and now your body slows way down so it's normal ratio of carbs:fat energy source is higher fat, and the carbs can now come from that slower amino acid conversion which isn't efficient enough, now your body is breaking down muscle you aren't using or is least used to provide that.

So up to that point, you are burning same amount of fat you were going to burn at whatever pace you are going, but by having several runs where you can eat between and refill stores, much less likely to burn off a tad bit a muscle, and never get to point of burning off a lot.

But it was never a fat vs muscle option. It's carbs vs muscle.

And the solution is to just slow down, just like you'd need to do in a race to finish successfully and not be walking at the end. I've never hit the wall in a marathon - went the correct pace, and no mid-race fueling needed either but a little sports drink for the blood sugar and electrolytes.

Sorry OP, going totes off-topic for a minute but heybales fixed a misconception of mine and I wanted to thank him!

A mile is roughly 100 calories burned regardless of speed or how many you do back to back.

The pace of that mile makes a difference. But agreed it's the same in chunks or at once.
http://www.exrx.net/Aerobic/WalkCalExp.html

I am now running late for work because I fell down the informational rabbit hole about the differences between "gross caloric burn" and "net metabolic burn."

"Thanks to the Syracuse researchers, we now know the relative NCB of running a mile in 9:30 versus walking the same mile in 19:00. Their male subjects burned 105 calories running, 52 walking; the women, 91 and 43. That is, running burns twice as many net calories per mile as walking. And since you can run two miles in the time it takes to walk one mile, running burns four times as many net calories per hour as walking."

Well, I'd be lying if I said I didnt start running just because I have an old treadmill, and was looking to burn calories to trigger weight loss. BUT, BUT, BUT..... I can honestly now say I am enjoying how I can run faster and am not as out of breath. I am noticing changes in my endurance that I definitely like, so even though I still want weight loss and calories burned, I am definitely becoming a big fan of actually getting healthier. Who woulda thunk it?

PS. (Warning: big tangent coming): I am also noticing other changes since running/working out in general - I am handling the heat of the summer much much better. I used to sweat like crazy (no joke) and be so uncomfortable in anything about 77 or so degrees, and I am much more comfortable and not sweaty now. Its actually a very dramatic difference from any other summer I have had, and this is the first summer I have been consistently pushing my body physically, so I think it has to be that. I love this side effect. Also my face when I started running was tomato red after 1 mile at 5.7, and now is just pink after 1 mile at 6.5. THAT FEELS AWESOME.

Whoo Hooo for you!!!!!!!!! I think you are asking smart questions (I learned a lot!) and have a wonderful attitude! Keep up the good work!!!!