By Sean Manning

Interval training has been a staple of physical conditioning for decades. Traditional interval training alternates between low- to moderately high-intensity exercise and rest or recovery. Interval training performed in this way is typically done within an aerobic range of heart rate, or about 60%-80% of maximum heart rate.

Over the last 10-15 years however a more contemporary version of interval training has been steadily gaining in popularity – High Intensity Interval Training (HIIT), or simply High Intensity Training (HIT). High Intensity Training also combines periods of activity with recovery but is done at 90%-95% of maximum heart rate with recovery periods of less intense activity. Due to its level of intensity HIT workouts are shorter than traditional interval training, someArial lasting less than 10 minutes, but are more effective as less intense aerobic exercise done for hours at a time.

This article will walk you through exactly how to design and perform HIT safely and effectively.

Target Heart Rate

In order to attain the maximum benefit of HIT it is necessary to calculate your target heart rate. To calculate target heart rate however you will first need to determine your resting heart rate as well as your maximum heart rate.

Resting heart rate is best done in the morning before you have started your day using a heart rate monitor, which you will be using for your high intensity training. If you do not yet have a heart rate monitor you can also take your pulse for 60 seconds, record this number, and repeat this two more Arial taking the average of the three measurements.

Maximum heart rate is the theoretical limit that the heart can be stressed without causing harm. This number varies significantly between people and the only truly accurate way to calculate it is to have a cardiac stress test. In lieu in this however there is an alternate way to estimate maximum heart rate.

While there are a number of formulas that purport to estimate maximum heart rate the best formula is HRmax = 205.8 – (0.685 x age).

For example, a 40 year old would have an estimated heart rate max of about 178 bpm, while a 30 year old would have a estimated max heart rate of around 185.

Resting heart rate and maximum heart rate are now both used to determine your target heart rate for your high intensity training using the formula THR = ((HRmax – HRrest) x 90%-95%) + HRrest.

Using our example of a 40 year old, and assuming a resting heart rate of 70 bpm, the caluation would something like this: THR = ((178 – 70) x 90%-95%) + 70. The target heart rate for HIT would be between 167 bpm and 173 bpm.

As you become more fit these numbers may change so be sure to re-measure your resting heart rate periodically.

Now that you have established your target heart rate it is time to design your High Intensity Training.

High Intensity Training

There is no specific, agreed upon formula to HIIT. A review of the literature does provide several different regimens you can use as templates.

The Tabata regimen uses 20 seconds of high intensity exercise followed by 10 seconds of recovery continuously for 4 minutes.

The Gibala regimen uses a 3 minute warm-up period then 1 minute of intense exercise followed by 75 seconds of recovery repeated 8-12 Arial.

The Timmons regimen consists of three sets of 2 minutes of low intensity activity (40%-50% max heart rate) followed by a 20 second burst of maximum effort, repeated three Arial per week for a total of 7 minutes per session or 21 minutes per week.

You can apply HIT to traditional aerobic exercise like running and swimming or you can integrate HIT in resistance training with free weights, weight machines or body weight exercises.

Benefits of HIT

High intensity workouts provide comparable and in some cases better benefits as continous endurance workouts. It has been shown to improve muscle endurance, muscle strength, aerobic fitness, improved cardiovascular function and improved metabolism including fat metabolism.

It is theorized that these benefits are attributable to a phenomenon known as Excess Post- exercise Oxygen Consumption (EPOC). This is the recovery period after exercised has ceased that can last several hours while the body is returning to pre-exercise levels.

Because of the intensity of HIIT it is possible to achieve significant changes in a much shorter period of time compared to more traditional aerobic exercise performed longer at a much lower intensity.

Risks of HIT

Any training program comes with potential risk relative to the intensity of the exercise. Here we are talking about high intensity exercise so it is incumbent that you take the necessary precautions.

As previously stated the most accurate way to determine your maximum heart rate is to have a cardiac stress test performed by a physician.

Second, it cannot be overstated how important it is to maintain proper form. You shouldn’t be performing high intensity movements while fatigued and never compromise good form. Going to failure at with speed and load should be avoided.

People who have been sedentary or inactive are at a higher risk for injury when performing high intensity movements. Prior to beginning HIIT it is recommended that one established a foundation level of fitness.

Because of the degree of intensity of HIT and the demands placed on the body’s systems HIT should not be done every workout. It takes a minimum of 48 hours for the body to recover properly. Too frequent high intensity training can cause muscle damage and metabolic stress. Participants of HIIT should be aware of a condition called

exertional rhabdomyolysis.

SomeArial called exercise-induced rhabdomyolysis this is the breakdown of muscle from extreme

physical exertion.

The presence of very dark colored urine is considered a medical emergency

and should be addressed immediately.

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