I found this nice older study that showed how exercise intensity and duration affect calories burned. First, the study looked at how many calories were burned following exercise (EPOC - excess post-exercise oxygen consumption). The researchers compared different combinations of intensity and duration.
EPOC (liters)
%VO2 max
20 min
50 min
80 min
30%
1.01
1.43
1.04
50%
3.14
5.19
6.1
70%
5.68
10.04
14.59
As you can see, intensity made the biggest difference. 20 minutes at the highest intensity burned more post-exercise calories than any length at the lowest exercise, and more than 20 or 50 minutes at the moderate intensity. At 80 minutes, post-exercise calorie burn was 15 times higher in the highest intensity group versus the lowest intensity group.
The researchers then looked at the calories burned during exercise to see how large the afterburn effect really was. Here's a table that looks at total calories burned (both during and after exercise).
Total Exercise Cost (liters)
%VO2 max
20 min
50 min
80 min
30%
20.48
53.20
84.23
50%
38.95
100.46
160.59
70%
58.30
147.48
237.17
Again, intensity was the key factor as going from the lowest intensity to the highest intensity tripled the total calorie burn.
I found this nice older study that showed how exercise intensity and duration affect calories burned. First, the study looked at how many calories were burned following exercise (EPOC - excess post-exercise oxygen consumption). The researchers compared different combinations of intensity and duration.
As you can see, intensity made the biggest difference. 20 minutes at the highest intensity burned more post-exercise calories than any length at the lowest exercise, and more than 20 or 50 minutes at the moderate intensity. At 80 minutes, post-exercise calorie burn was 15 times higher in the highest intensity group versus the lowest intensity group.
The researchers then looked at the calories burned during exercise to see how large the afterburn effect really was. Here's a table that looks at total calories burned (both during and after exercise).
Again, intensity was the key factor as going from the lowest intensity to the highest intensity tripled the total calorie burn.