#Armour39 Review, a Heart Rate Monitor from Under Armour #IWILL

The following post is sponsored by Fitfluential on behalf of Under Armour. I take pride in my reviews as being honest and this is no different.

As I mentioned in a few previous posts, I have been using the Under Armour Armour39 during my workouts to track my heart rate, calories burned and intensity.
Armour39 Review

The gist: The Armour39 ($99) is made for any athlete, any sport. It tracks the duration of your workout, calories burned, intensity and of course heart rate. Through Bluetooth connectivity it sends the data to either a free app that you can download to your smartphone or directly to a watch ($199) on your wrist bought separately, which can also send the data later to your phone for further analysis.


What’s different:

The measure of willpower is kind of fun and unique to Under Armour. It is measured based on your maximum heart rate and how close you come to it or hover around it for the duration of your workout. Your max HR is calculated using a 10 minute endurance test. It’s pretty quick and if you do it first thing in the morning without a warm up, chances are it will not be accurate, so take note. You can also plug in your max HR based if you want. I did this based on a simple and less precise age formula (220 minus your age for men, 226 minus your age for women) and that should be sufficient until you have the time to take the test properly. You can set your goal willpower at the start of your workout, so for a light day your goal surely would not be close to a 10.0 but more like a 5 or 6.

The data below is for a Barry’s Bootcamp workout and is very evident we use an HIIT formula. My intensity says 100% when I’m at or above what it thought was my max heart rate at the time.

Under Armour Intensity Armour39

I used just the watch for a spinning workout but used the app for the rest. At the end of your workout, it gives you a summary of your average intensity, heart rate and total calories burned. I’ve used various apps and chest strap over the years, and I must admit that this is as accurate as they come! For reals. I know my limits, when they are and are not pushed. This calorie expenditure is dead on.

Under Armour39

Your workouts for the past 90 days are stored on the app to look at and compare willpower quickly.

What makes the strap great and different from other Bluetooth HR chest straps:

If you walk out of range from your phone, you don’t have to worry about the data not getting back to the program. It saves the information and is transferred to the app once it is back in range within 90 minutes. If you are taking a zumba class at the gym and want to leave your phone in your locker, your data will still be recorded as long as you remember to start your workout on the Armour39 app before class starts. The app never crashed on me either.

The watch costs $199 and is a little big in my opinion. It is not a GPS so if you wear it running it will not track distance, pace or anything like that. The Bluetooth chest strap will however sync with other iPhone apps that connect to heart rate monitors like RunKeeper and Pear.


During spin class at Recycle when I wore the watch, the lights were very low. I didn’t realize it but the Armour39 band has a blue light that glows on and off like a slow heart beat so you know it’s connected. If you wear a light top, the blue light glows through! I was sort of embarrassed at first when I first noticed but quickly remembered no one looks at anyone but themselves in those gym mirrors. Let’s be honest.

I also couldn’t see my heart rate on my watch because it was so dark. My fault for not reading all the directions! I hit a few buttons without any luck to turn on the backlight and was nervous I stopped recording my data. Luckily, I did not. This is a great feature for people like me in my opinion. It asks you at least two times if you really want to stop your activity, in an attempt to prevent the “butt dial” of workout technology. If the price tag is a bit shocking, you do not need the watch to reap the benefits from the Armour39 strap and in fact, you cannot use the watch and app at the same time. I prefer just the app to be honest which is free.


I wore the strap while doing a run through of my workout at Barry’s, and then taught it to two classes. This was my overall burn seen above!

The chest strap is also a little bigger than other straps I have worn but did not chafe at all. I’ve gotten little cuts on my chest after wearing other chest straps for my long runs (8+ mi). I didn’t go over 6 miles with the Armour39 but it was very comfortable and hardly noticeable once on. It’s also smooth and does not drastically bulk out from under your top, making supermans bearable.


I love tracking my heart rate. The Armour39 I felt was accurate, comfortable and with a $99 price point, on par with other Bluetooth heart rate monitor devices. What I like is that the data is stored if you are out of range from your phone so you don’t have to have it with you at all times.

If you want to track a run, just go ahead and use RunKeeper in the background to track miles, speed and elevation. I like to compare the heart rates against each other – nerdy I know. I did this and it burned a solid 30% of my battery during a 6 mile run. I also had Songza streaming though.

If you don’t have a Bluetooth heart rate monitor yet, you are missing out on some seriously geeky and awesome fitness apps that will measure your workouts and improve your overall fitness. The Armour39 is a great option.

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