Several studies in the last few years have shown that high intensity short interval training is a very effective way of exercising. This means that if you exercise fairly hard, you don’t have to do it for very long, and you don’t have to do it very often either.
The reviewed research compared two exercise protocols in healthy slightly overweight men (Tjønna A E, et.al., 2013). Both groups did a combination of walking, jogging and running on a treadmill at 90 percent of maximum heart rate, but one group exercised for only 4 minutes, while the other group did 4 minutes 4 times with 3 minutes of active recovery at 70 percent maximum heart rate in between the sets. Both groups participated in a warm up of 10 minutes at 70 percent of maximum heart rate and a 6 minutes cool down. Both groups exercised for 10 weeks, three times a week.
Even if one group exercised considerably less than the other group, maximum oxygen uptake (VO2max) improved approximately the same in both groups. VO2max is associated with a marked reduction in all-cause mortality risk.
Systolic blood pressure decreased with 6.2 mmHG in the group which exercised for 4 minutes once, while it was reduced with 3.2 mmHG in the group that exercised more. Diastolic blood pressure was reduced with 7.7 mmHG and 6.3 mmHG respectively. Surprisingly both systolic and diastolic blood pressure was reduced more in the group that exercised less.
Fasting blood glucose was reduced with 6percent in the group which exercised only 4 minutes and with 5 percent in the other group.
The only results that improved more in the group that exercised more was cholesterol , LDL cholesterol and fat loss.
That is quite impressive for the group that exercised a lot less.