You could find a zillion articles and blogs talking about High-Intensity-Interval-Training HIIT. I would just re-iterate what it is for the sake of completeness of this post.
What is HIIT?
HIIT is a cardio exercise strategy of alternating short period of intense exercise with less intense recovery period. The exercise could theoretically be anything. It could be running and jogging, fast and slow reps of any cardio exercise. The goal is to bring your heart rate up so anything that does so should be fine.
There have been a lot of studies that have proven HIIT helps in bringing your body into a fat shredding state.
The cost benefit ratio of HIIT is much higher than a lot of other workout techniques. For instance if your goal is fat loss, 10 minutes of HIIT will be more effective than 30-40 minutes of light jogging.
Long term vs Short Term ?
HITT is suitable for long term as there are no known negative effects.
I have been doing HIIT as long as I have heard of it. The reason – time. For me and most people I know the biggest challenge in consistent workout is lack of time. Well you can say good bye to that excuse. Even 5-7 minutes of HIIT could help meet most of your workout requirements.
As is the case with most people, I do not workout consistently the year round. There are periods fo months sometimes when I don’t do anything. For getting back into HIIT regime, I start with different ration of high vs low intensity exercise and gradually work my way up.
For example, I would start first day after a few months with 3 reps
30 sec sprint at 80% of my maximum capacity.
60 sec walk/jog.
Within 1 weak, I would increase number of reps to 5-6. Then I start working on reducing the low intensity duration. The goal is to eventually reach 1: 1 i.e. 30 sec sprint at 80-90% intensity and 30 sec walking/jogging.
If you are having trouble with starting at 1:2, you can also start with 1:3 or 1:4. The goal is to keep improving gradually till you reach 1:1.
I prefer to do it early morning in fasted state (Refer to Intermittent fasting) and it works quite well. My average workout duration is ~7-8 minutes.
HIIT has helped me loose a lot of body fat fairly quickly multiple times. At maximum, I have lost 8 pounds in 6 weeks using a combination of HIIT and intermittent fasting.
Whether you have time to do long workouts or not, whether you want those 6 packs or just loose those extra pounds, HIIT is the way to go. Burn more calories, remain in fat shredding mode for longer and save some time. Its a win-win situation. So far I have not heard of any major side-effects of doing HIIT for long term. Ofcourse if you have heart-issues, you should consult your doctor before giving it a try.