The Cardio Workout: Interval Training Basics
Workouts with varying levels of intensity, called interval workouts or interval training, can provide an ordinary exercise routine with an extra fat burning boost and can dramatically strengthen the heart and build endurance. Interval training can also help support motivation and follow-through, since variety keeps the workout process interesting. But this intense form of training may not be for everyone. And technique matters; to maximize the benefits, it’s a good idea to enlist some guidance before incorporating intervals into a regular exercise plan.
Heart Rate and Interval Training
Our maximum heart rate is the BPM, or beats per minute, that occur when the heart is at its highest level of exertion. When the heart is hammering away at this high speed, it’s gathering oxygenated blood from the lungs and delivering nourishment to all of our body systems, including our muscle tissue, at the highest possible rate. A body under stress requires plenty of burnable fuel and fast oxygen delivery in order to stay in motion and repair damaged cells.
But the heart can’t maintain efficient oxygen and fuel delivery at this speed for very long. Eventually, if we continue working out at a high level of intensity, our bodies will move from aerobic (or oxygen based) delivery to anaerobic delivery, which involves lower oxygen dependence.
In the aerobic zone, we’re working hard, but not so hard that we’re outpacing the delivery capacity of the heart. As long as we stay in the aerobic zone, our bodies are burning fat for fuel. As we push ourselves into the anaerobic zone, our heart rate speeds up and our bodies begin to burn primarily carbohydrates for fuel.
Calculating Maximum Heart Rate
Structured interval training will depend on our ability to determine when we’re in one zone versus another. And in order to make that determination, we’ll need to start by calculating our maximum heart rate.
To measure heart rate, or BPM, simply use two fingers to locate the pulse in the carotid artery (the neck area just under the jaw) or the wrist. Count the number of pulses in a six second period and multiply that number by 10.
For a healthy adult person, a general rule of thumb states that maximum heart rate equals 220 minus age. (As always, those who are working with chronic health conditions or recovering from an illness should consult with a doctor in order to calculate their maximum heart rate and make an appropriate exercise plan.)
Dividing a Workout into Zones
Maximum heart rate, once it’s determined, can be used to calculate the slower rates, or zones, of intensity that make up an interval training workout. When we’re working in a lower aerobic zone, usually called Zone 1, we’re operating at 65-75 percent of our maximum heart rate. When we’re in a higher intensity anaerobic zone, called Zone 2, we’re working at 80-85 percent of our maximum heart rate.
Some trainers consider anything higher than 85 percent as Zone 3, but this is a very high level of intensity that’s difficult for most people to sustain for more than a few minutes at a time. Most of us should start by building an interval workout that moves between Zones 1 and 2.
The Benefits of Interval Training
The term “interval training” is not attached to any formal definition or specific set of heart rate guidelines; it just refers to an exercise routine build on varied levels of intensity. When we workout hard for a short period of time, and then slow down for a bit, then spike our activity levels back up again, we’re interval training. This is the case even when we aren’t carefully controlling our movements or measuring our heart rate at each shift in intensity.
No matter how structured, intervals can help us workout harder for short bursts without becoming exhausted or bored. If we push ourselves to the limit, then recover, then push ourselves again, we spend a higher percentage of workout time at that peak intensity level and we also tend to enjoy the process more and have more fun.
And of course, tricking our bodies into spending more time at higher levels of exertion can tone the heart muscle, which can improve our endurance and provide general health benefits for our entire cardiovascular system. When artery walls are stronger and more elastic, blood pressure is better controlled. And when blood pressure is under control, we experience a cascade of benefits including a reduced risk of heart attacks and strokes.
Building an Interval Training Plan
For beginners or those who are just getting off the ground, simple interval training can involve walking or jogging broken up by pauses for push-ups and squats.
More intense and structured interval training should be tackled only when we’re able to stay at the higher levels of Zone 1 for at least 30 minutes at a time. When you can live in Zone 1 for 30 to 45 minutes, feel free to start working out in intense sets that keep you in Zone 2 for three full minutes, then drop you down into Zone 1 for another three minutes
A powerful heart can move from one zone to another fairly quickly. That is to say, the transition from one gear to another happens faster when the heart is strong, flexible and responsive. Ideally, when we move from a higher to a lower zone, our BRM should drop by about 20 beats within one minute.
If your heart can drop quickly into recovery mode and then speed back up to higher levels of sustainable intensity, feel free to add intensity and duration to your interval training program. Just remember: Interval training can make the time pass quickly, which can lead some people to do too much too fast. If you’re pleasantly exhausted at the end of an interval workout, excellent. But utter, painful exhaustion can sometimes sap the motivation that got us there in the first place. As always, pay attention your body. Listen to its signals and balance your goals between ambition and realism.
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