High Intensity Interval Training (HIIT) is a wildly popular method of exercising that focuses on bursts of intense activity followed by short periods of rest and recovery. A typical HIIT workout consists of roughly 60 seconds of high intensity training and 90 seconds of rest, and then repeated for 15 minutes or so.

This style of workout has been proven very effective at increasing cardiovascular health, and studies have shown that in just two weeks of HIIT, young men developed significant increases in resistance to insulin, helping prevent Type II Diabetes. Another benefit of HIIT is an increased capacity for oxygen in your lungs. If you train via HIIT, you will find it much easier to climb a flight of stairs or go on a light jog without becoming winded.

If you're looking to get "swole," then you might be overlooking HIIT as a method for bulking up. Studies have shown that in the 24 hours after a HIIT workout, the body produces 450 percent more human growth hormone than normal. HGH is the stuff that encourages your body to build lean muscle mass. HIIT has also been shown to increase your metabolism substantially in the 24 hours following the exercise. Anytime you have the opportunity to increase your metabolism, do it. It not only aids in weight loss, it keeps the body healthy on the inside as well.

Find the routine that is right for you and do it! The faster you begin, the faster the results start pouring in. You will need a heart rate monitor to perform these exercises with maximum effectiveness. For the strenuous part of the exercise, your goal should be to have your heart pumping at 85 percent of its maximum rate.

To find your maximum heart rate, subtract your age from 220 and you will have a decent estimate. Training beyond 85 percent of your maximum heart rate increases the risk of injury without providing any added benefit. Without further ado, let's "HIIT" the gym:

HIIT On A Cycle
This one has sets that are a bit longer than most HIIT routines but is good for those looking to emphasize Lance Armstrong-style leg endurance. You will find yourself biking the French Alps in no time.

Routine No. 1
-- Do a three-minute warmup period at medium pace with no incline/resistance. (60-80 RPM)
-- Thirty seconds in, increase the resistance and add a level of steepness but keep the RPM above 80.
-- Keep repeating until you cannot hold a pace above 80 RPM.
-- Rest for two minutes and repeat as desired. Your goal should be to work up to a 15-minute cycle workout. The 15 minutes should include the five-minute warm-up and cool-down.

Routine No. 2
-- Bike for five minutes to warm up.
-- Cycle at maximum intensity for one minute.
-- Coast for one minute.
-- Repeat the maximum intensity set for one minute.
-- Rinse and repeat for 15 minutes with a five-minute period of light activity at the end.

The "Old Fashioned"
This one combines the earth and your feet to create a powerful workout that will have your glutes set ablaze. In other words, we will be sprinting.

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-- Do a light jog for five minutes to warm up.
-- Sprint for thirty seconds (if you're new) or one minute (seasoned vet) at near maximum intensity.
-- Go back to a light jog for one minute to a minute and a half.
-- Repeat for 17 minutes, at the end of your routine do a five-minute cool-down.

Row Your Boat
Whether you are on the row team at Princeton or just want to build back and shoulder strength while maintaining cardiovascular health, try this HIIT exercise.

-- Warm up for three minutes or so.
-- Immediately after the three minutes are up, go hard for 60 seconds.
-- Take a 60-second break.
-- Do another 60 seconds of maximum intensity.
-- Repeat for 17 minutes while allowing for a five-minute cool-down.

The Butt Routine
For this one you will need either a Stairmaster or a set of stairs that takes you roughly 60 seconds to climb. Your butt will be a masterpiece after doing this for a couple of months. Since we are going to be putting a lot of stress on our legs and glutes, let's make sure to stretch before with this one.

-- Ascend and descend the stairs for five minutes or so. Do this at a light pace, as this is our warm up.
-- After your warm up, climb the stairs or Stairmaster at maximum intensity for 45 seconds to a minute.
-- Rest for one minute. If you are really looking to build those legs, do some light lunges during your rest.
-- Do another set of high-intensity stair climbs.
-- Repeat for five minutes, then do a five-minute long cool-down (continuous and light.)

The One That No One Likes
Most people do not like doing pushups. It's a hard exercise, and if you don't have a lot of upper body strength, it can be especially strenuous. Perform this HIIT exercise if you want to build upper body strength while maintaining cardiovascular excellence.

-- For this one, we are going to break the mold and warm up with five minutes of jumping jacks. You will feel like a kid again.
-- After your warm-up, plop down and pound out a set of pushups at maximum intensity for 60 seconds.
-- Take a minute and a half break.
-- Keep doing sets of pushups/breaks for five minutes.
-- Do another five minutes of light jumping jacks for your cool down.

The Core Crusher
This one is a staff favorite here at Dual Fit. Our favorite lifting routines call for a rest day consisting of cardiovascular exercise and abdominal work. This high intensity interval training routine combines the best of both worlds. Utilize this workout if you are looking to build up core strength while maintaining cardiovascular fitness.

-- Much like with the pushup routine listed above, we will start by doing a five-minute light jog to warm up.
-- Head over to your gym's power tower (or captain's chair) and do 60 seconds of full-out, high-intensity knee raises. You will feel the burn, rest assured.
-- Rest for 60 seconds.
-- Do another set of intensity-filled knee raises and rest. Repeat for five minutes.
-- Do a five-minute light jog to cool down.

Feel The Greatness
As you can see, HIIT is very versatile. You can mix and match and even create your own routines. The main emphasis for someone new to HIIT should be a routine that goes hard for 60 seconds and then breaks for a minute to two minutes, depending on the exercise involved. As you get accustomed to HIIT, you can lower the work to rest ratio from 3:1 to something like 2:1 and eventually even 1:1. Just make sure that you are ready before jumping to the next level.

Since you are going to be performing these exercises at a very high rate of speed and intensity, you will want to make sure to stretch thoroughly before the workout. You know how easy it would be to pull a hamstring during sprints or to pull a quad on the cycle without stretching and warming up? Very easy. Since we are going to be pushing ourselves to the maximum, warm-ups and cool-downs are extremely important as well.

If you have heart disease or a family with a history of heart problems, you will want to consult a doctor before beginning a high intensity interval training program. If you smoke, are sedentary, are overweight, or are over the age of 60, then it would be wise to consult a doctor before jumping into an exercise like this. If you are out of shape, start out slow and gradually work your way up to a fitter, healthier you.

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