Interval training involves alternating short, intense bursts of activity with a recovery period ─ usually a slower, easier version of the high-intensity exercise. You can, for example, repeat a series of 5-minute intervals of walking for 4 minutes then jogging for 1 minute for a total of 30 to 40 minutes. If you prefer walking, or are working your way up to jogging, you can add short periods of brisk walking to your regular walking pace using the same principle: walk at your regular pace for 4 minutes, then speed up for 1 minute.
According to UAB exercise physiologists, interval training is especially beneficial for people who have been exercising for a time, have hit a plateau, and want to reestablish fitness increases or weight loss.
Increasing the intensity of your exercise, even for short periods, can help you burn more calories and improve your cardiovascular fitness faster than exercising less intensely at a steady pace. Interval training provides these benefits by working your body aerobically and anaerobically. The aerobic system uses oxygen to convert the body’s stored carbohydrates into energy, burning calories and allowing you to exercise for extended periods. During anaerobic activity, which improves your cardiovascular capacity, the body draws on glycogen stored in muscles, providing energy for short, intense activity such as sprinting or weight lifting. Anaerobic exercise produces lactic acid, which is what makes your muscles burn during intense activity or ache afterwards.
Interval training requires no special equipment and you can add it to most fitness regimens. All you need is control over the speed or intensity of your workout. Rowing machines, treadmills, elliptical trainers, and stationary bicycles all allow you to manipulate speed and resistance levels. In addition to increasing speed for the high-intensity portion of training, you also can increase the resistance or incline of your machine. You can switch up the high-intensity intervals during a single workout, sprinting or walking quickly during some intervals and increasing the resistance or incline during others.
You can easily work interval training into your outdoor run, walk, or bike ride. For high-intensity work, increase your speed or head up hill. As noted, a good way to begin is working in simple 5-minute intervals with an alternating pattern of intensity. Here are some tips for safely incorporating interval training into your workout:
Ø If you’re running or walking on a machine or outside, make sure your shoes are up to the task. Over time, shoes lose their ability to stabilize and cushion feet and legs. Moving faster increases stress on your body, so good shoes are crucial. Most runners replace their shoes every 3 to 6 months.
Ø Warm up for 5 to 10 minutes before beginning intervals.
Ø Start slowly. Try incorporating two to four intervals into your usual workout and gradually increase the number of intervals as your fitness level improves.
Ø Listen to your body. Interval training is challenging and pushing too hard during high-intensity periods can result in injury. You may have days when you are tired and need to work at an easier pace. Gauge your daily energy level and tailor your workouts accordingly.
Ø Make sure you’re recovering adequately. During the high-intensity, anaerobic portion of your workout, you should be working within 80% to 90% of your maximum heart rate (MHR). To reap the full benefits of interval training, your heart rate needs to come down to about 65% of your MHR during recovery. Many exercise machines have tables that show estimated MHR for different ages or you can subtract your age from 220 to get a rough estimate of your MHR. Then multiply that figure by .80 and .90 to define 80% and 90% of the max.You also can gauge recovery by how hard you are breathing. During recovery, your breathing should become easier and you should be able to carry on a conversation and feel ready for the next high-intensity push.
Ø Check with your doctor before beginning interval training if you are a man older than 40 years, a woman older than 50 years, have a chronic health condition, take medications regularly, have a family history of heart disease before age 55, or are pregnant, overweight, a smoker, or do not exercise regularly.
Breaking up your exercise routine with interval training not only boosts your fitness level, it can help pass the time quickly and keep exercise boredom at bay. For more information on interval training, visit Runner's World magazine online. The site, which UAB experts recommend for its consistent, accurate information, offers a host of tips and training routines and has sections geared to new runners.