In order to perform interval training, there are a couple of things you need to know. First of all, if you haven't been doing any kind of regular exercise, do NOT start doing intervals. If your over age 35 or significantly overweight you should go get checked out by your doctor and get the all clear to start exercising. As I mentioned earlier, your heart is a muscle and like any other muscle if you haven't been using it and then suddenly you go all out, you can injure it. What kind of injuries do heart muscles get? You guessed it, heart attacks! If your in the clear to begin working out, focus on just doing 20-30 minutes of cardiovascular exercise at about 40-50% of your HRmax 3-5 days per week for the first 3 weeks. Then you can consider upping your intensity and working up to interval training.
The next thing you need to succesfully begin interval training is to figure out your Target Heart Rate zones. There is a lot of debate about HR Target zones. I'm here to tell you that the zones you see on virtually EVERY piece of cardio equipment in gyms today are bogus! They are NOT based on any modern scientific data. Every individual has a different HRmax and it is difficult to find unless you are in a laboratory setting. The erroneous equation that you see on cardio machines use 220-age to establish a HRmax. This is derived from a quasi-scientific study in the 1920's (almost 100 years ago!!!) and not backed up by any modern data and I fail to understand how this myth lives on! I can tell you personally that I am 33 years old which would mean my HRmax would be 187 according to this outdated calculation. I ROUTINELY climb large hills on my bike where my HR goes up to 191 and trust me, it's a hard effort but I can sustain it for several minutes which leads me to believe my true HRmax is probably around 200. I have trained hundreds of clients over age 50 who easily get their heart rates up into the 170's and 180's when exercising. I have another female client in great shape who at age 41 struggles to get her HR above 155bpm when exercising.
A better starting point would be to use the Karvonen formula which still has it's flaws but actually takes into account your RESTING HEART RATE when coming up with a target heart rate range. Here is a great calculator that will give you a side by side comparison of the two methods. Be sure to measure your resting heart rate first thing in the morning after waking up, while sitting down or still lying in bed, preferable after waking up without the aid of an alarm clock and before having any caffeine.
Keep in mind, we are looking at general fitness improvement and weight loss for average people. For someone looking at serious world class level of competition we would absolutely seek lab resources to hone in SPECIFIC Hr numbers.
|Polar HR Monitor|
Once you have figured out your HRmax the most basic way of doing intervals is to simply work at an effort that takes you up to 85% of your max then bring it back down to 50% of your HRmax. I do this by setting the treadmill at say 9.0 and running for 1 minute, then bringing it back down to a walking pace of 3.5 for one minute. This is the most simplest of intervals. IF you do the math 9.0 +3.5/2 =6.25 mph. So over the course of 20 minutes of intervals, you will cover the same amount of ground as if you ran steady at 6.25 but the difference is that you challenged your heart above what it is used to and then allowed it recover. This process strengthens the heart muscle and your cardiovascular capacity. Over time, you will find that your steady state runs improve.
I could write pages and pages about interval training, this is just to scratch the surface and to get the average person thinking about upping your intensity and not getting caught up in doing the same old thing. If you find that your working out as consistently as ever but your results are lacking, start throwing some basic intervals into the mix. As always feel free to comment below or on my Facebook page with your specific questions about interval training.
P.S. Heres a great clip of Rachel in action doing some intervals last week!