Short 20 min Interval cardio workout plan

This week I'm doing an experiment on the effectiveness of short interval cardio. I know a lot of us rather workout less if we can still get the same result. I mean why spend one hour on the treadmill if you can get the same result by working out say 20 minute.

But the question is, can you get the same result by working out less? Well this is the point I try to find out this week. So far for the last 8 weeks I have been under the assumption that more is better. So I have been consistently doing cardio for 60 minutes 6-7 days a week and on top of that I have been trying to do strength training 3 times a week. However that needs serious time commitment and I wonder if why I get busy I find myself an excuse that I don't really have the time to go to the gym. Another downside of long workouts is the possibility of injury and wear an tear of our joins.

My new cardio consist of the following formula which I learned when I was doing body for life 10 years ago. I will give this combo 2 weeks to test the result. I'm still doing cardio 6 days a week in the morning and weights 3 times at night because I tried to do the cardio after weights and it just doesn't work. It is too intense of a work out and my body just didn't have the energy.

Effort 5 should be easy get your heart rate going but you should be able to be at this difficulty for extended period of time. When I started body for life level 5 is like 3 mph speed on treadmill. I'm at 4 mph now

On treadmill
Minute 1    level 5.   4mph
Minute 2.   Level 5.  4mpr
Minute 3.  Level 6.   4.5mpr
Minute 4.   Level7.   5mpr
Minute 5.   Level 8.  5.5mpr
Minute 6.   Level 9.  6mpr
Minute 7.   Level 6.  4.5mpr
Minute 8.   Level 7.  5mpr
Minute 9.   Level 8.   5.5mpr
Minute 10.  Level 9.  6 mpr
Minute 11.  Level 6.  4.5mpr
Minute 12.  Level 7.  5mpr
Minute 13.  Level 8.  5.5mpr
Minute 14.  Level 9.   6mpr
Minute 15.  Level 6.   4.5mpr
Minute 16.  Level 7.   5mpr
Minute 17.  Level 8.   5.5mpr
Minute 18.  Level 9.   6mpr
Minute 19.  Level 10 6.5mpr all out( you should be in heart zone 5 now really super intense for me was like 175-180 hr)
Minute 20. Level 5 cool down

Around minute 15 is really tempting to give up but resist the temptation and you will feel greate at the end.

You should adjust your levels according to your own body. You can start at level 5 be equivalent to 2mpr and increase say .2. Notice your work out if you feel you can do more then add a little higher intensity next time. If its too hard reduce it (start slowly you can always slowly add more)it may take a few try to get it just right and from that point on you will need to increase it periodically (once a week would be good) because you will get stronger. If the pace gets too fast you can increase the difficulty from increasing the incline setting.

I find it useful to write down ahead what I'm doing in my notebook and have that in front of me when I workout so I don't get confused. My average hr from this 20 minute workout is 155 as oppose to one hr on treadmill I'm usually at average of 130-140hr range