At some point in your fat-burning endeavors, you’ve probably been directed to take your pulse for a few seconds, then multiply that number to get your beats per minute. Perhaps you’ve grabbed the sensors on a treadmill to find out how hard you’re working — or just out of pure curiosity. And when you do, do you ever wonder: What’s the point? Can knowing your heart rate really help you reach your weight-loss goals? If you’re trying to drop unwanted pounds, not win a triathlon, does all that heart-rate stuff really matter?
Wonder no more: The answer is yes. It turns out that a fitness-by-numbers approach can churn out remarkable weight-loss results. It helps you upgrade your fitness, too, of course. But even if you don’t give a fig about fitness, heart-rate training is still a fat-blaster’s best friend.
Monitoring your heart rate helps you avoid the common mistake of always training in the same “gray zone” of intensity, says Troy Jacobson, head endurance sports coach at Life Time Fitness in Chanhassen, Minn. And that means you avoid wasting time and energy on workouts that don’t deliver the results you’re after. “Heart-rate training allows you to precisely control the intensity of your workouts to ensure you get the benefits you’re seeking — including fat loss.”
People instinctively fall into a moderately challenging effort range because it makes them feel like they’re working hard enough, but without getting too uncomfortable. As a result, says Jacobson, these exercisers “stagnate pretty quickly.” In other words, they stop losing weight, even though they continue to work hard.
To keep losing fat (and avoid getting bored and discouraged), you need to break out of the gray zone and do a variety of cardio workouts that visit a range of intensities. And a heart-rate monitor can help you do that by giving you appropriate, customized intensity targets for each type of workout.
On the following pages, we’ve assembled a series of heart-rate workouts designed with weight loss in mind. To do them, you’ll need a heart-rate monitor with the ability for you to manually program your target zones. (For guidance on other available features, see our web extra “Choosing a Multifunction Heart-Rate Monitor” at elmag.com/fitness-technology.)
The next step is to determine your anaerobic threshold, or AT (the point at which your body starts to use significantly more sugar than fat for fuel). A highly individual number influenced both by genetic factors and your current fitness level, your AT provides a helpful benchmark to use in setting target heart rates for different types of workouts.
By far the most accurate way of determining your anaerobic-threshold heart rate is with professional assistance at a facility that provides AT testing services. (See “Fitness Technology: 3 Ways to Work Out Smarter Than Ever,” for more on metabolic testing.)
If you don’t have access to this type of testing, try this do-it-yourself alternative: Hop on any piece of cardio equipment and, after warming up, increase your exercise intensity in incremental steps every few minutes, checking your heart rate at each step. Pay attention to how you feel. Note when you start to feel uncomfortable — your legs start to feel heavy and you may experience a burning sensation in your muscles. Your breathing will shift toward heavier, more rhythmic pants. Your heart rate when you reach this intensity level will reflect your approximate AT.
Know Your Zones
Heart-rate-based workouts typically employ a five-zone system for setting target heart rates. Here are the five zones Jacobson uses in designing workouts for his clients. Once you know your AT, calculating your personal zone ranges is simple math. For example, if your AT heart rate is 150, calculate your zone 2 range by multiplying 150 by 0.7 and 0.9 (70 to 90 percent of your AT). Your zone 2 heart-rate range would be 105 to 135.
Note that your AT will change as your fitness level changes, so be sure to retest it and refigure your zones every six weeks or so.
Heart-rate monitor? Check. Anaerobic threshold determined? Check. Target-heart-rate zones calculated? Check.
Now — ideally, over the course of the next week — you’re ready to perform these three cardio workouts, which work together to maximize fat loss by stimulating metabolism in different, but complementary, ways.
Jacobson designed each of these three workouts so you can perform them in just about any cardio exercise modality, from outdoor cycling to the elliptical trainer. Eventually, you’ll do each workout once a week on nonconsecutive days. On alternate days, strength train to build metabolism-boosting muscle or perform additional moderate-intensity cardio exercise.
Workout 1: Aerobic Intervals
“This is a zone 2 interval workout that helps build your aerobic base,” explains Jacobson. Zone 2 is associated with the body’s peak rate of fat burning, and in it you not only burn a lot of fat but also train your body to burn more fat at rest by developing your cellular fat-burning machinery.
A 2005 study published in Medicine & Science in Sports & Exercise reported that overweight men who performed interval workouts for four months experienced significant changes in the activity of fat-burning enzymes and a dramatic increase in the amount of fat they burned throughout the day.
The intervals in this workout are longer and are done at a lower intensity compared with those you might be accustomed to doing. Avoid any temptation to work above zone 2, except during the warm-up. Jacobson notes that this workout can also be used as a recovery session after a high-intensity day.
This workout takes about 35 to 70 minutes.
Begin with five minutes of activity in zones 1 and 2. Then increase the intensity each minute for three minutes so your heart rate peaks at or near zone 4 for at least 30 seconds.
Do four five-minute intervals in zone 2, resting 30 to 60 seconds after each.
For more of an endurance-building workout and twice the fat burning, repeat this main set a second time.
Finish the workout with five to 10 minutes in zones 1 and 2.
Workout 2: Threshold Intervals
“Workouts like this one that target AT heart rate are great for weight loss,” says Jacobson.
Here’s why: When doing threshold intervals, you burn a lot of carbohydrates, and the more carbs you burn during a workout, the more fat you burn for the next several hours.
These workouts will also nudge your fitness level upward, meaning that it will become easier over time for you to work out longer and at higher intensities.
“This type of workout should be followed by a lower-intensity workout such as Workout 1 the next workout day,” says Jacobson. That recovery time is essential, he points out, for you to get the full benefit from the work you’ve done because of a postworkout increase in your metabolic rate.
This workout takes about 40 to 50 minutes.
Do the same warm-up as in Workout 1, but rest for two minutes before starting the main set.
Do six 90-second intervals in zone 3. Rest for one minute after each interval except the last, which should be followed by three minutes of rest. Now go for five to 10 minutes steady at your AT heart rate (top of zone 3/bottom of zone 4). Do five minutes the first time you try the workout and gradually increase the duration of this effort in subsequent sessions.
Finish the workout with five to 10 minutes in zones 1 and 2.
Workout 3: Power Builder
The power builder, a.k.a. sprint workout, helps you shed fat in two ways, says Jacobson. First, it burns even more carbs than threshold intervals and thus even more fat during the next several hours. Second, by boosting your heart rate to the highest levels, the power builder dramatically increases your cardiovascular fitness, enabling you to perform all your cardio workouts at higher intensities without spiking your heart rate. This workout helps develop greater overall muscle strength and endurance.
The only downside is that it’s tough! “You should be in good condition before incorporating this workout into your routine,” says Jacobson. “One should only employ this intensity after six to eight weeks of aerobic- and threshold-intensity training. And always start with a substantial warm-up.”
This workout takes about 35 to 45 minutes.
Perform the same warm-up as in Workout 2, including the two-minute rest.
Do three 30-second intervals in zone 4 with one minute of recovery in zone 2 after each. Next, do 10 15-second sprints in zone 5. Recover for 45 to 75 seconds in zone 2 after each.
Do 10 minutes of activity in zones 1 and 2.
Matt Fitzgerald is a running and triathlon expert who has authored and coauthored several books, including Maximum Strength (Da Capo, 2008) with Eric Cressey.