The ups and downs of interval training
ASK THE TRAINERS
From low intensity to high to low, working out in different heart-rate zones keeps the body from hitting a plateau.
The basics of interval training are tough to figure out without doing some math first to figure out one's maximum heart rate.
A general formula for calculating that number is 220 minus age. To work in a lower aerobic zone, in which the body burns primarily fat for fuel, calculate 65% of the maximum heart rate. To work in a higher anaerobic zone, calculate 85% of the maximum heart rate. The anaerobic zone, in which the body burns primarily carbohydrates for fuel, is the high-intensity portion of the interval (some trainers may put it at about 80%). For those who like precise numbers, some gyms and training facilities offer more technically advanced testing, but that can be costly. Heart rates can be taken manually at the wrist, and some cardio machines have built-in monitors (although accuracy varies). Heart-rate monitors provide the best readings.
Tony Ambler-Wright
Scottsdale, Ariz.-based master instructor for the National Academy of Sports Medicine:
We take our clients in and out of three zones: Zone 1 is 65% to 75% of your maximum heart rate, and Zone 2 is 80% to 85% of your maximum heart rate. Zone 3 is 85% to 90% of your maximum heart rate, and you usually don't want that to comprise more than 10% of your total training volume for the week because it's so intense. But ultimately the goal is to get everyone to that point where they could exercise at that level of intensity.
You should be able to sustain the upper level of Zone 1 for 30 minutes before trying to do some interval training. If you're able to do half an hour to 45 minutes in zones 1 and 2, you're a good candidate to incorporate some Zone 3 work in small intervals, within a workout that utilizes zones 1 and 2.
The work-to-rest ratio can change. You can go up into Zone 2 for three minutes, then down to Zone 1 for three minutes. Then you can work a 2-1 ratio of work and rest. A good rule of thumb is -- and this is where the heart-rate monitor comes in handy -- that when you drop down a zone, you should see a 20-beat-per-minute drop in your heart rate within one minute. That's a good indicator that you're in the recovery zone.
People have a tendency to push themselves too hard, too soon. A lot of people don't do the preparatory work in getting the body used to exercising and improving their base, where the body is utilizing fat efficiently as a fuel source, before doing intervals.
