I really don't dig running fast than faster than having to slow down to fast. So I was thinking of doing this,
1. warm up with a 5 min run
2. run for 2 mins really fast
3. walk for 1 min
4. then run really fast for another 2 mins
and repeat walk / run 7 or 8 times for like 25 mins.

My goal is loose fat doing this along with my lifting routine. So I'll be running on an empty stomach.
I plan to do it no more than 3 times a week.
Thoughts?

Well...HIIT is more bent on shorter intervals.

Like 30 sprint, 30 second walk.

Allright, I'll try that then, thanks

You need a nice diet when running. Its the best way to lose weight. eat Right, run right, lift right, and you will turn out alright!

damn hiit killed me today.. I got to 16 minutes and had to walk..I was tireddd

I sometimes don't make it the full 20 minutes, but I'm working my way up to it. One thing I noticed is I run much better with shoes on. I was struggling with no shoes and had no idea why.

Do you have a football field near you?

I can't help myself.....Why were you running with no shoes on?

I grew up in an area which gave me tough skin on my feet. :P

sometimes I do a quick jog for 3 mins, then sprint for 30 seconds, then walk for 10 mins. try that

lol I dont think Id be able to make it without shoes =P

Try this routine:

30 Second as hard as you can sprint
4 minutes rest
Repeat minimum of 4 times, more if you can.
(No more thant 3 times per week)

Some explanation is in order:

All energy systems in your muscle, aerobic and anaerobic, produce ATP, the chemical the muscles use for energy. (ATP=Adenosine TRI phosphate).

There is a little ATP hanging out inside your mucle cells. With exercise, it lasts only ~5 seconds (2-10 seconds depending on who you read).

It is converted into ADP (Adenosine DI phosphate)

ADP is then converted to ATP by Creatine Phosphate donating a phosphate. Creatine Phosphate is how your body stores readily available high energy phosphate to generate immediate ATP. It is the next energy system your body uses, and generates energy beyond the 10 seconds, but only for about 30 Seconds to 1 minute.

When you exercise so hard and fast that your muscles need a lot of energy fast, ATP is converted to ADP, and then ADP can also be used for energy, converting it to AMP (Adenosine MONO phosphate).

The harder/faster you exercise, the more AMP is generated. The cool thing about AMP is that AMP is a key. This molecule stimulates a myriad of enzymes to work in your muscles. The more AMP, the faster, stronger the response. In fact it is AMP that stimulates both the aerobic enzymes for glycolysis and the Anaerobic enzymes for the Krebs Cycle to increase activity (which is why the above stated exercise regimin has been shown to increase not only speed, but able to double endurance in just two weeks.)

It takes 4 minutes of rest for your muscle to resynthesize creatine phosphate. As soon as you stop exercising, Creatine begins taking phosphates from ATP, which generates ADP. See what is happening?

By sprinting again after 4 minutes, there is more ADP in the cells, which means when you sprint, you will force even more AMP to be generated, further stimulating the enzyme systems in the cell. Each set of Sprint/Rest further increases AMP levels in the cell.

Why is this important for FAT LOSS?

One of the enzymes stimulated by AMP is called AMP-kinase. Simply put this enzyme has the responsibility of restoring your muscle cells energy storage. Repeated sprints force use of the glycogen in your muscles, and AMP-Kinase tells the cell STOP USING SUGAR FOR ENERGY, I GOT TO USE IT TO FILL THE WAREHOUSE. YOU WILL HAVE TO LIVE ON FAT FOR AWHILE. Causing the cells to increase fatty acid oxidation for energy.

In animals, chemically stimulating AMP-Kinase, causes them to lose weight.
In humans, the higher the AMP levels in the cell, the more active this enzyme gets. During endurance running (jogging) your body becomes more efficient at generating ATP from ADP, and so very little AMP is produced. More endurance training actually decreases the amount of AMP-Kinase activity a person generates during exercise. Which is why people plateau with running. In order to lose weight, they have to run longer to burn more calories.

In the only study yet to evaluate this, two groups exercised for 20 weeks. One group typical aerobic running. The second group, Sprint training. It was calculated that the sprint group burned 1/2 the calories of the endurance group. But at the end of the study, the sprint group has lost 6 times the subcutaneous fat compared to the endurance group.

Without enough studies to answer more questions about this, you could extrapolate some things from the basic science.

One study showed significant increase in AMP-Kinase activity after one episode of sprinting (for a couple of minutes) that lasted about one hour. Hence, if you wanted to maximize the impact of that enzymes activity, you could sprint one or two times, and then continue with an hour jog which should burn more fat calories during that time. Hypothetical, yes, but based on some good science. Just a thought. I hope this helps. Let me know what you think.

Duane