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Cardiovascular fitness: HRrest, HRmax, HRR, HR Recovery and VO2 MAX.

My HR Rest - February 12, 2011
My resting heart rate on February 12, 2011

My resting heart rate on February 12, 2011

Regular readers of this blog know how important I feel it is to track and evaluate progress on a fixed schedule. In general I recommend that a complete set of soft tape measurements, a body fat reading (using a 7 or 9 point skinfold caliper) and scale weight are taken first thing in the morning once per week. I choose to perform these measurements and evaluate my progress every Sunday.

The above-mentioned measurements are perfect for tracking body composition changes, and you can gauge your muscle strength easily enough by the weights you’re using in the gym, but what about cardiovascular fitness? No one can deny that the heart is the most important muscle in the human body, so if you care at all about your health (and athletic performance) it makes sense to stay on top of how the ol’ ticker is functioning, too.

Because one of my priories on this cut is cardiovascular fitness and overall athletic conditioning, I am going to start including some cardiovascular-specific measurements in my weekly stats. This morning I’m going to talk about the simple tests I’ll be performing and how they relate to my overall cardiovascular health and abilities. Also, what better day to discuss the heart than Valentine’s day? 🙂

Most of these tests can be performed with a watch and a pulse (you probably already have both of these). If you’re at all serious about your health and training, one of the most valuable tools you can have in your fitness toolbox is a good heart rate monitor. I use the Timex Ironman, and am very happy with it. I’ve found that a lot of heart rate monitors are overpriced and come loaded with useless features, but this one strikes a nice balance between functionality and price. It’s rugged, waterproof, very accurate with good signal strength between the monitor and chest strap and has the features I need to track my workouts and perform all the tests I’m about to discuss.

HRrest is your resting heart rate. This test is best performed first thing in the morning before you drink coffee or even get out of bed. Simply put on your heart rate monitor and lay calmly for a few minutes. The lowest reading you see is your HRrest. In general the better shape you’re in the lower your resting heart rate will be. The normal HRrest range is between 60 and 100 BPM. In the photo (above) you can see that my HRrest is currently 46 BPM. Actually, I took this measurement mid-day on Saturday, so that reading may be tad higher than my actual HRrest. While 46 BPM is considered excellent, back in 2004 my resting heart rate was even lower at 38 BPM. Of course I was 7 years younger then, but I would not be surprised if by the end of my cut I was back around that level. By comparison I think Lance Armstrong has a resting heart rate in the low 30s. A few elite athletes have recorded resting heart rates in the 20s!

HRmax (HRM) is your maximum heart rate. Men can estimate their HRM by subtracting their age from 220, while women should subtract their age from 226:

HRM = (220 – age) (men)
HRM = (226 – age) (women)

The only way to find out your real HRM is to wear a heart rate monitor and do very strenuous exercise until your heart rate maxes out. Be aware that attempting to reach your HRM can be dangerous if you are not in good health. If in doubt, always talk to your doctor first.

Heart Rate Reserve (HRR) is simply:

HRR = (HRmax – HRrest)

The bigger the number the better. As you get in better shape and your resting heart rate decreases, your HRR will increase.

Heart Rate Recovery (HR Recovery ) is an excellent indicator of overall conditioning and cardiovascular health. HR Recovery is measured after performing strenuous exercise for a given period of time and then measuring how far your heart rate drops two minutes after stopping that exercise. For example, perform some form of taxing cardio, take note of your heart rate, rest two full minutes and then check your heart rate again. The difference between those two numbers is your HR Recovery. So, if you complete your cardio session with a heart rate reading of 171 BPM and two minutes later your heart rate is 110 BPM, your HR Recovery is 61. A HR Recovery of 61 is is considered excellent, by the way. If your HR Recovery is 12 or less then you need to see a doctor.

I measured my HR Recovery today after 4 sets of 20 Bulgarian Split Squats (1 minute rest between sets). At the end of the 4th set my heart rate was 185 BPM. After exactly 1 minute of rest my heart rate had dropped to 141 BPM. After the second minute of rest my heart rate was down to 117 BPM, which puts my HR Recovery at 68. I expected my HR Recovery to be good, but this was a very pleasant surprise considering I’m only six weeks into my cut!

One of the cool features of the Timex Ironman is that it automatically computes your HR Recovery after stopping the timer in Chrono mode: simply hit the “stop” button and rest for two minutes – the result will be stored with the rest of your workout data (total exercise time, average heart rate, lowest heart rate, maximum heart rate, time spent in preferred heart rate zone, total calories burned, etc).

VO2 MAX is a representation of the maximum amount of oxygen that can be transported and used by the working tissues during a fixed period of time. It is one of the best indicators of overall cardiovascular fitness, but a truly accurate VO2 MAX measurement requires specialized equipment to measure oxygen and carbon dioxide levels as you perform strenuous exercise. The data is plugged into the Fick equation, which is:

VO2 MAX = Q(CaO2 – CvO2)

…where Q is the cardio output of the heart, CaO2 is the arterial oxygen content, and CvO2 is the venous oxygen content.

Researchers at the Department of Sport Science at the University of Aarhus, Katrinebjergvej came up with an equation that estimates VO2 MAX using the ratio between HRmax and HRrest (here is the abstract on Pubmed). The Uth—Sørensen—Overgaard—Pedersen equation is:

My estimated VO2 MAX using the Uth—Sørensen—Overgaard—Pedersen equation is 62.93 ml/min/kg (15 * 193 / 46). This is considered excellent (I’m 42):

V0<sub>2</sub> MAX Chart

V02 MAX Chart

It will be interesting to see how the Uth—Sørensen—Overgaard—Pedersen estimate compares to my actual VO2 MAX when I have it tested in a lab.

Look for all of these new measurements to be included with my weekly stats starting next Sunday!