From what I've heard, but anyone feel free to correct me if I'm wrong...

..is that sprinting burns calories fairly quickly, while running or jogging at a slower pace but for longer distance taps into fat stores and begins to burn fat rather than carbs.

Number of calories burned is primarily a function of distance covered.

So, if you run faster, you cover a longer distance in a given time, thereby increasing the calories burned per minute. For example, you will burn (approximately) the same number of calories running 28 minutes @ 7 minutes per mile, as you do runnning 36 minutes @ 9 minutes per mile.

Having said that, you can cover a greater total distance and by running slowly than running fast. I doubt you can "sprint" 10 miles, but jogging 10 miles isn't a big deal. It's also inconceivable that anyone can "sprint" the same distance in 10 minutes as they jog in 40 minutes, so your example is not realistic. A fast runner might do 2.5 miles of total sprints in 10 mintues, if they can run 10 quarter mile sprints at 60 seconds each. Someone that fast would certainly cover more than 5 miles in 40 minutes even at a recovery jog pace.

Its very complex.

Walking at low intensity or normal daily activities burn primarily fat but very little.

Low to medium intensity running burns a combination of carbs and fat.

High intensity exercise will rely mainly on carbs during the exercise but the recovery period is much longer and you may burn more fat overall.

Any exercise is better than no exercise. A combination of the three may be the way to go with the emphasis on low to moderate intensity running as outlined by runforthechilis.

quote:<HR>Originally posted by dg12:
Wrong

Distance is one factor plus intensity. In a 1 an hour of aerobic running slowly you"ll burn a certain amount of calories. Crossing over to the anaerobic or alactic systems the metabolism kicks into overdrive elevating it hours longer<HR>

So true, dg12. So true.

quote:<HR>Originally posted by dg12:
Wrong

Distance is one factor plus intensity. In a 1 an hour of aerobic running slowly you"ll burn a certain amount of calories. Crossing over to the anaerobic or alactic systems the metabolism kicks into overdrive elevating it hours longer<HR>

The calories burned during the run is strictly a function of distance, There is no effect on total calories burned by altering the duration of the run by changing pace. A 5 mile run burns X calories regardless of the pace at which it is run.

The question remains regarding what post exercise burn takes place. Since post exercise caloric burn IS a pumped up metabolism by definition, it simply confuses the issue to even mention metabolism. The post exercise burn must be actually doing something with the energy. Calories are, after all, just a measure of energy and, since energy can neither be created nor destroyed, the post exercise calories that are burned as a result of the exercise must actually manifest themselves in some manner. In effect, the post exercise burn must be used up in producing muscle, or heat or some form of physical activity. It is literally impossible to burn calories and have nothing to show for it.

So, what possible differences could there be in a person who in one instance burns 500 cal (for example) in a 5 mile easy run compared to the same person after a 500 cal, 5 mile tempo run. It is not at all clear that one or the other situation would expend more post exercise energy on tissue building and even if one could make a case for a larger expenditure in one case or the other, it would certainly not be a huge difference. I guess if the tempo run had been sufficiently vigorous to significantly damage muscles etc., then I suppose there could be a larger post exercise burn.

It is likely the tempo run would result in a longer cool down time during which the HR and respiration would be more elevated and I fully expect that a calorimetric measurement would show the post tempo burn to be higher but I would be very surpeised if it was much higher for any significant time.

So, while the post exercise burn of a high intensity exercise can reasonably be expected to burn more, It would not likely make a major difference. For example, both the runs described above burned 500 calories during the run. I would be very surprised if the 'after burn' in either case was more than 10% and, of course, the difference would be even less. Perhaps someone has some real data.

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gotta run...

quote:<HR>Originally posted by TheMountaineer:

Yes, but we are not running once we stop.<HR>

Yes, but our metabolism is elevated for a period of time after we stop running. The higher intensity we were running at, the bigger the metabolism boost during those post-run hours.

This is concept behind using HITT for fat loss (high intensity interval training). Many bodybuilders use this method to get cut before a show. Even the Body For Life program reccommends 20-25mins of this type of running to shed weight. Many times if calorie intake is not adequate, long distance running causes muscle loss as well.

It's old school to think that the only way to lose weight is by increasing mileage. Look at the bodies of long distance runners vs. those of sprinters. Sprinters are able to MAINTAIN their muscle mass while shedding bodyfat. Do sprinters run long distances? No. They sprint. They have quite low bodyfat without racking up the miles.

Something to think about...