A recent study identified "high intensity exercise [to be] more beneficial than traditional endurance training" for those concerned about their cardiovascular health.
47 boys and 10 girls volunteered for the study. The kids were randomly assigned to two groups - the moderate intensity group and the high intensity group.
Both groups performed 3 exercise sessions a week for 7 weeks. The moderate intensity group was asked to jog, non-stop, for 20 minutes while the high intensity group was asked to run a series of 20m sprints in a period of 30 seconds.
By the end of the study the moderate intensity group had 420 minutes of exercise and the high intensity group had only done 63 minutes. The moderate intensity group had burned an approximate 4,410kcals while the high intensity group had only burned 907.2kcals.
"The results revealed that both groups demonstrated improved CVD risk factors. However, the total exercise time over seven weeks was six times higher for the MOD group compared to the HIT group. Thus, significant improvements in CVD risk factors in the HIT group occurred in only 15% of the total exercise time."
This states that the body benefits MOST from high intensity training - kids in the high intensity group had same results in less than a fifth of the time as the kids in the moderate intensity group. This suggests that, "brief, intense exercise is a time efficient means for improving CVD risk factors in adolescents."
[Medical News Today]: Better A Sprint Than A Marathon: Brief Intense Exercise Better Than Endurance Training For CVD