Heart Rate Myth
Being in the Zone
Being in the zone isn’t just for athletes any longer. Whether it’s in your group exercise class or during personal training, you’ll find more recreational exercisers strapping on their heart rate monitors to stay in the “fat-burning zone” and get the most of their workout.
There’s just one fundamental problem as Fabio Comana, ACE’s Exercise Physiologist, sees it: Max HR calculations aren’t just imperfect, they can actually lead exercisers down the twilight zone.
Max HR = 220 – age
Consider this: The standard formula, which calls for subtracting your age from 220 to calculate a particular value for a training zone can deviate as much as 12 beats.
“For someone whose maximal heart rate is lower than what the actual maximal heart rate is, they may end up overtraining whereas if the maximal heart rate is higher than their actual heart rate, they may be undertraining,” says Comana. “Also, the 220 minus your age calculation tends to overestimate exercise heart rates in younger populations and underestimate exercise heart rate in older populations.”
Max HR = 208 – (age x 0.7)
A better mathematical formula is Dr. Hirofumi Tanaka’s 208 minus 0.7 times your age. At least with the Tanaka formula the standard deviation is less, or 7.4 beats vs. 12 beats for the Haskins and Fox formula. Hence, with a 20-year old client, using Max Heart rate calculation, the actual heart rate may be 212 or 188 vs. 207 or 194 using Tanaka’s formula.
Most clients exercise to achieve cardiovascular fitness combined with weight loss or maintenance. While this overall goal doesn’t seem to change much over the years, the means to get there seem to follow trends in fitness, Comana says.
Going High or Low?
In the last eight to nine years, there has been a reversal from (focusing on) low-intensity, fat-burning classes (such as low-intensity step or aerobics classes) to more high-intensity bouts of exercise (boot camps for instance).
Both approaches are counterproductive, especially for unconditioned, sedentary persons wanting to lose weight. A sedentary, healthy person who keeps working out in Zone 1 (50 to 60 percent of Max HR) is unlikely to burn enough calories to achieve the desired weight loss.
Neither will performing high-intensity exercise bouts where people burn predominantly carbohydrates. Considering that the normal carbohydrate intake for average Americans is about 50 percent to 55 percent of their daily diet, adding a hard cardio workout trains muscles to store more carbohydrates. This increases the glycogen storage capacity, which is desirable for endurance athletes who want to carbo-load, but not for recreational exercisers. The added water (2.4 grams to 2.7 grams) per grams of glycogen may lead to increased weight gain, which will leave you with a very unhappy client.
Focus on the Middle – Caloric Quality and Quantity
“The key is to teach clients to burn fat efficiently,” Comana says. The best way to do this is by focusing on quality first, and teaching the body how to burn fat. Then it’s time to focus on caloric quantity. For trainers and clients who want to work with heart rate zones, Comana suggests performing an appropriate sub-maximal heart rate test, such as the One Mile Walk Test or a Step Test to estimate maximum heart rate. This way, trainers have a better platform for figuring out proper exercise zones for their clients.
Talk Threshold Test
If Comana had his way, more trainers would rely on the talk test to assess clients’ exercise intensity.
University researchers, such as Drs. Asker Jeukendrup and Carl Foster have supported the idea that using ventilation threshold One (VT1) may be just as effective as heart-rate monitoring for differing training zones. Clients who speak in complete sentences are in the aerobic zone, which corresponds to less than 80 percent of maximum heart rate. When clients can speak only in short bursts, they have moved into the threshold zone, which is effective for increasing endurance, but can only be sustained for short periods.
Comana’s recommendation for training clients: Create a two-zone model with zone 1 being the fat-burning zone approaching the ventilation threshold (VT1) when breathlessness develops; and zone 2, being a 10-beat zone above VT1.
Clients initially will spend most of their exercising time in zone 1, so they can learn how to burn fat more efficiently. After about three to six training sessions, depending on your client’s fitness level and progress, incorporate aerobic intervals on a 1:1 ratio. For instance, have a client exercise a bit harder (between zone 1 and 2) for five minutes, back off the intensity for five minutes, and then repeat the cycle. After a few weeks of training, retest the ventilatory threshold of the same client and recreate appropriate exercise zones. This allows trainers to increase clients’ fat-burning capacity slowly and safely while using appropriate training zones to help them gain a higher fitness level and wanted weight loss.
The problem with the five Max HR zones—Zone 1 (50 percent to 60 percent of Max HR); Zone 2 (60 percent to 70 percent of Max HR); Zone 3 (70 percent to 80 percent of Max HR); Zone 4 (80 percent to 90 percent of Max HR); and Zone 5 (90 percent to 100 percent of Max HR Vo2 Max)—isn’t that they aren’t useful, Comana says. Finding the correct zone to train in can be tough to calculate.
However, in terms of how many calories you burn in each zone, researchers have learned a lot: In Zone 1, which is the lowest level and beginner-friendly, you’ll burn between three to five calories a minute. Training in Zone 2, where people will start seeing additional health benefits, burns seven to nine calories a minute. Training in Zone 3, or the cardiovascular fitness zone, will burn about 10 to 12 calories a minute. Most recreational exercisers may never want to cross into the anaerobic zone (Zone 4, which burns 13 to 15 calories a minute); but only the fittest clients should cross into Zone 5, which burns 16 or more calories a minute.
Since most Americans in weight-loss mode ultimately rely on the number they’ll see looking down standing on their bathroom scale, trainers may be well served to develop an exercise program that doesn’t enslave their clients to technology, but rather teaches them to pay closer attention to their breathing, and learn how their bodies react to exercise.
--------------------------------------------------------------------------------
Marion Webb is the managing editor for the American Council on Exercise and an ACE-certified Personal Trainer. For specific fitness-related story ideas or comments, please email her directly at
marion.webb@acefitness.org.
[img]http://i88.photobucket.com/albums/k195/lockaroundmyheart/Not%20Real%20Pictures/Animations/diddle-1.gif[/img]
