The HRM

One of my best little fitness friends is my Polar Heart Rate Monitor (HRM). Seriously. The little guy goes everywhere with me when it comes to workouts, running, walking, whatever. Here are a few reasons why I love HRM for working out.

The one I have. Love the red!

Reasons:

1). Calorie burn on gym equipment tends to be VERY inaccurate.

To test this, during today's workout out at the new gym down the road, I got on one of their "better" ellipticals (they have a couple different kinds) and entered my weight (entered 110 even though my HRM is set at 112 just to give the machine a teeny edge up) and started the workout.

When the HRM told me I burned 100 calories I checked the machine to see what number it gave. The verdict: 175 calories! A 75% increase! 

You may ask how I know my HRM is accurate, and that would be a good question. The HRM calculates calories based on the heart rate and how hard the body is working. Polar and a few other companies have perfected their devices which have been tested against calories calculated various ways (e.g. using VO2 max). They are only estimations as well, but much better ones with +/- 15-25% inaccuracy.

This is a nice review article of calories burned in different exercises using a HRM and other fitness trackers:

http://www.wired.com/playbook/2012/08/fitness-trackers/

2). Knowing how much to rest in between sets.

This is kind of a tricky thing. I try to listen to my body in between sets when I lift. When I'm doing more complex lifts (deadlifts, squats, even pull-ups sometimes) I find that my body needs a lot more rest compared to when I do a set of curls or tricep dips. This makes sense. But my body and mind don't always agree on when I should do the next set. Sometimes I get amped up to do the next set because I'm going for a max and try to do it too soon after the previous set. Sometimes I'm tired and groggy and end up zoning out or delaying the next set because my brain is just tired. My HRM actually tells me how my heart feels. It spikes during sets (especially during the aforementioned complex lifts) and then I can watch it drop. When it gets below a certain number, that's a good indication that I can start the next set soon. If it gets too far below, its a good indication I am taking too long.


3). It gives good indication of getting in shape.

I've done the following experiment many times: I take a week or so off from cardio/lifting (sometimes for vacation, sometimes just because my body needs it) and when I go back I do the same workout (same time & intensity) as I did the week before I took off. I always find that my heart rate is several (between 6-8 bpm) higher when I get back.

Now, I'm not actually getting out of shape in a week. Not entirely. But my body has to work harder after that week because it's not used to it. The body is good at adapting and becoming efficient. The same workouts, if done repeatedly and regularly, will require less work the longer you do them. I use my HRM to tell how hard my body is working, and how, if I'm at the same intensity doing the same exercise, if I'm adapting or not.


4). I just like numbers.

Honestly. I like knowing how high my heart rate gets doing lunges across the gym. Or how many calories I burn in a mile. Numbers nerd.