VO2 Max and Heart Rate Zones

In the past, I have generally trained by feel. For example, making sure I can carry on a conversation during an easy/long run. I have a Garmin Forerunner 220, so I track information about my pace, heart race, and cadence, but I haven't really utilized that information effectively.

Sometimes during speedwork I see that my heart rate is in the 180s after a hard sprint. Is that too high? Am I pushing too hard? Based on the highly inaccurate but ubiquitous "220-your age" formula, my max heart rate should be 220-46=174. This would suggest that a heart rate in the 180s is cause for concern, to say the least! I wanted some accurate heart rate guidance for the marathon training cycle I am about to begin.

Active Metabolic Assessment

I turned to the "Active Metabolic Assessment" offered by my gym, Life Time Fitness. This assessment identifies your heart rate training zones and VO2 Max using the VO2 breath test. In this test, you have a breathing mask that measures the volume of oxygen you are using while running on a treadmill at progressively harder levels. In addition to identifying your VO2 Max, the test identifies your individual heart rate training zones along with information about each zone, such as the percentage of fat/carbs you are burning in each zone and what type of training each zone is good for.

The Test

I was nervous about the test. I tend to doubt my athletic ability, so anything that formally assesses it makes me a little uncomfortable. I worry that it will expose me as a fraud and reveal that I have no business calling myself a runner. Silly, huh? Fortunately, the test was being administered by a cute personal trainer who is also known as my husband, Rick. That helped me feel a little better about it.

Rick preps my breathing mask

The actual test consists of two parts; a warm-up and an assessment. During each part the treadmill speed gets progressively faster and you rate how you feel at different points while the breathing mask captures information about the volume of oxygen you are using and a heart rate monitor captures your heart rate.

Before the test I wanted to know what "7" was supposed to feel like.
What is between "Hard" and "Really Hard"? (almost really hard?)
During the test, I was actually able to identify a level between them. Go figure!

Rick fitted me with a breathing mask which I was able to keep after the test. When you come back for re-assessments, you can bring the mask with you and the cost of the assessment is lower. I felt a bit like Hannibal Lecter with the mask on, and it took a few minutes to get used to the sensation.

The leads from the mask connect to a machine;
the black strap around my arm captures heart rate.

We went through the warm-up phase which lasted about 8 minutes. During that phase the speed kept increasing and I went through the "easy" to "hard" levels based on my assessment. Then I got to rest for 5 minutes, after which we went through the assessment phase. The assessment phase lasted about 14 minutes and I went all the way to the "really, really, hard" level. And then we were done and I was rewarded with a multi-page printout of data and results - my favorite!

Testing underway

The Results

I love data, and I was excited to get 10 pages of information! I learned my individual heart rate zones, my VO2 max, and received lots of guidance about how to apply this information in my training. 

My current VO2 max indicates I am in good shape. My Zone 5 HR range is 171-190 beats per minute, so that speedwork reading in the 180s after a sprint really isn't cause for concern. There is guidance about which zone is appropriate for different types of training, and I've updated my Garmin profile to reflect my individual zones and VO2 max. Now I can train by heart rate, setting my Garmin to alert me when I leave my intended zone.

My Heart Rate Zones

I am eager to apply this information during my training over the next few months. I am also looking forward to a re-assessment in 3 months so I can see how my capacity has evolved after a cycle of dedicated marathon training.