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Exercise Metabolic Testing: More Than Just Bragging Rights – Part 3

Posted Jan 21 2013 9:59am

Let’s take a look at an example of how the EMT can be successfully utilized in a triathlon program
JoAnn is a 35 year old age group triathlete with a goal to complete an Ironman triathlon in June. At the beginning of the year, she decides to undergo an EMT on her bicycle. Since she will be training with a heart rate monitor, she wants training and racing recommendations based on heartbeats per minute. She also wants to know how many calories she should be consuming during the race, and what type of caloric deficits she is creating during her training sessions.

At the lab, an exercise physiologist straps a heart rate monitor to JoAnn’s chest and attaches a neoprene mask to her face. After a 10 minute light warm-up on a the lab indoor  bicycle trainer, the EMT begins. JoAnn initiates the first part of the test by cycling at a resistance of 50 watts for three minutes. At the end of this stage, her resistance is increased by 25 watts. This pattern continues until JoAnn’s carbon dioxide to oxygen ratio reaches approximately 0.85, which indicates about 85% intensity. She reaches this intensity at a resistance of 175 watts, or eighteen minutes into the test. After a brief cool-down, she sits down with the exercise physiologist to review her data.

The physiologist points out that nine minutes into the test, at a heart rate of 132 beats per minute (bpm), she was burning 60% fat, 40% carbohydrate, and a total of 600 calories per hour. On a graph that shows total fat calories burnt, this heart rate turns out to be the peak of her fat utilization, indicating maximum fat burning intensity, or aerobic threshold. JoAnn can now program her personal heart rate monitor with a training zone that is three to five heartbeats above or below 132 bpm. Thus during her long, distance bike rides, her heart rate monitor alarm will begin to beep whenever she is below 129bpm or above 135bpm. She can use this same alarm during the Ironman to ensure that she is cycling at maximum efficiency without risking premature fatigue.

The test results also show that at a heart rate of 154bpm, JoAnn’s carbon dioxide production begins to peak, indicating increased lactic acid production and AT. From this value, JoAnn knows that she can train her body to effectively buffer lactic acid and improve cardiovascular fitness if she performs her interval training sessions at intensities near 154bpm, or AT. She also knows that if she exceeds 154bpm during Ironman, she will begin to rapidly deplete her valuable carbohydrate stores. So during her longer training rides, although she may stray outside her aerobic threshold of 129-135bpm (especially on hills), she should practice avoiding intensities that exceed 154bpm, since the body has a difficult time returning to peak fat utilization after “crossing” the anaerobic threshold barrier.

JoAnn is also given a table that indicates the total number of calories, carbohydrates and fat utilized at each heart rate. If Joann knows her average heart rate during any given training session, she can simply match this number to the same heart rate on the table. For example, every Wednesday she trains for one hour on the bicycle at an average heart rate of 148bpm. According to the table, she burns 780 calories per hour at this heart rate, with 600 calories from carbohydrate and 180 calories from fat. JoAnn can now ensure that she is replacing those 600 calories of carbohydrate with proper post-workout fueling. For example, she might fuel with 200 calories of carbohydrate immediately after the workout, and 400 additional carbohydrate calories an hour later.

As mentioned previously, she can see from this table that at her maximum fat burning intensity of 132bpm, she is utilizing 600 calories per hour. Multiplying this number by 30-40% results in a value of 180-240 calories. During her long rides at aerobic intensity, JoAnn can now begin practicing a nutritional intake within this range, since this will be her goal heart rate range during Ironman.


As her fitness increases over the subsequent six months, Joann’s metabolic values will change, so she plans on repeating the test 4-8 weeks prior to Ironman. Most likely, her aerobic threshold and AT will occur at higher heart rates and higher caloric values.  Finally, if she ever decides to train with a power meter, she can use the same tables and graphs to see how the wattage on her bicycle correlates with any of these heart rate values and data points.

Since JoAnn completed her EMT on the bike, she should not use these same heart rate training zones for running. If an athlete is equally economical and has a similar training history and experience in both running and cycling, the heart rate training zones for running will be about ten beats per minute higher than the cycling heart rates. Because of the stored energy in the round wheels of a bicycle, most individuals are more efficient at cycling than running. Since the cycling leg is a large percentage of most triathlons, JoAnn was advised to undergo her initial EMT on the bike. But if she wants to accurately pinpoint her exact running heart rate zones, she would be recommended to repeat her test on a treadmill.

And of course, if JoAnn truly desires to take home the aerobic trophy and brag to her friends about her athletic superiority, she may just decide to take the EMT to the limits and find out her VO2max number. But the practical applications of her VO2max will pale in comparison to the practical and highly valuable information collected during her EMT.

Since the base season and off-season are the ideal periods to dial-in your proper training intensity zones and begin practicing appropriate nutrition intake, now is the perfect time to take an EMT. You can begin by contacting your local exercise physiology lab or sports performance center. Expect to pay $100-250 for this test, but insist beforehand that you be given full nutrition information for each heart rate during the test, rather than simply your heart rate training zones or thresholds. If you are able to harvest all possible information from your EMT, it will be well worth your efforts!

I hope this article series has been helpful for you! If you have more questions, or are interested in  coaching or training plans, just visit And have a great triathlon season!

Whoisben Ben Greenfield is the Renaissance man of the sport of triathlon.

He's a fast triathlete, a coach, a personal trainer, and much more more.

We recommend that you surf on over to , for more great training advice.

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