Walking vs. High Intensity Cardio

[Ukase]

I have been doing a modified cross-fit workout the past few months. 

Today, I rowed 100, 200, 300, 400, 500, 400, 300, 200, 100 meters - all rowed as fast as I could go. 

Squat, then lift 30# overhead, X10

Row 100 meters as fast as I can. 

Then do 10 push-ups.

Immediately after, Squat, then lift 30# overhead, X10

Then Row 200 meters ASAP, 

Then do 20 second plank. 

Then Squat, then lift 30# overhead, X10

then row 300 M, then curl 30#'s 30 times. 
Then Squat, then lift 30# overhead, X10,

Then row 400 Meters, then do 40 Mountain Climbers (get in a high plank, then alternate bringing legs up to chest) 
Then Squat, then lift 30# overhead, X10
Then row 500 meters, and do 50 lunges, each leg. 

Then repeat, but go backwards - 400M, 300M, etc. with the same exercises as above.
This workout took 52:24 minutes, burned 449 calories, with an average BPM of 110. 

This afternoon, I just went for a simple walk! It took 48 minutes, and according to my Charge HR, I burned 575 calories, with an average BPM of 129! 

I know the Fitbit is made to track steps, and not rowing or weight-lifting. But I thought the whole idea around Fitbit monitoring the heart rate was so it would be more accurate. 

During the row workout, I'm huffing and puffing! I am dripping in sweat. I can feel my heart racing! Yet, when I'm just walking, not even with any kind of speed, Fitbit thinks I'm working harder? 
What the heck is going on here? 

[Baltoscott]

Hi @Ukase.  Not sure if this will help, but do you start an activity on your tracker before you do the cross-fit workout?  On the Charge 2, I would use "workout."  That would tell your tracker you are doing something "active," and will result in a more regular sampling of your HR.

One problem for fitbit with gym workouts is that you don't do very many steps, and, depending on how energetic you are, maybe not much other discernible movement either.   Also, fitbit probably overweights movement a bit in calculating calorie burn because it measures movement well, and, at least in step-based exercise, it is a good proxy for calorie burn.  I think fitbit tries to compensate for this problem somewhat by sampling HR more often when you start an activity, and by making some baseline assumptions about calorie burn when you pick certain exercises like "Weight Lifting" or "Workout." 

If you don't start an activity and also do exercise that does not include many steps and limited amounts of other movement, you wind up with a low calorie burn, even if your HR is higher than normal.  Fitbit probably weights increased HR somewhat, but if it is not also accompanied by movement similar to fast walking or better, it probably attributes the higher HR to something that does not burn a lot of calories like food digestion, stress, or standing around.

BTW, you don't have start an activity when you are walking because your increased step count clues the tracker in and you wind up with an auto recognized activity.  

One other thought -- the 129 average BPM you got on your 48 minute walk seems too high for a walk.  I wonder if it was just a one-off bad reading.   Is that typical of your walks?  Checking my activities, I got about 88 average BPM on a 42 minute walk yesterday that covered 3800 steps.  And a weight lifting activity on the same day averaged 114 BPM.  (My resting BPM around 60).

[Ukase]

I have a Charge HR. I start the activity before the rowing class/crossfit. I don't ordinarily start it when walking.  It seems to know I'm doing a work out, but the fact that it thinks my heart is going 155 when I'm simply walking, compared to 155 when I'm busting my lungs - well, that tells me that this HR measurement isn't measuring accurately - which is the only reason to buy an expensive Charge HR vs the One, which is/was much cheaper. 

Clearly, there is room for improvement with the programming behind this gadget. 

[DominicJ]

None of your crossfit exercises are energy intensive, except the rowing, and that not massively so.  They are muscle intensive.
A plank is really hard on your muscles, but it doesn't consume much energy.

Squats, push ups ect, all designed to wear out your muscles, to make them bigger and stronger, not burn energy.

[Baltoscott]

When I read your first post I thought you believed that you weren't getting enough calorie credit for the cross-fit workout, and I focused mostly on that.  But on reflection, your average HR and the calorie burn rate for that workout seem about right.  Although it is not fully aerobic it still is 500+ calories an hour.  That's pretty high.

The walk you did, however, has what seems to me to be a very high (and probably wrong) average HR which is likely inflating the calorie burn for that activity.  I don't think you focused on it when I asked before, but is that average HR and calorie burn typical of your walks, or could it be more of a one-time misread by the Charge HR?

[SunsetRunner]

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@Baltoscott wrote:

The walk you did, however, has what seems to me to be a very high (and probably wrong) average HR which is likely inflating the calorie burn for that activity.  I don't think you focused on it when I asked before, but is that average HR and calorie burn typical of your walks, or could it be more of a one-time misread by the Charge HR?

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I'm not so sure. Most of the exercising carried out was in a sitting or lower position, therefore the heart does not need to beat as fast to get the blood to all parts of the body.  Walking on the other hand involves being upright so the heart does have to beat faster to get a good supply of blood to the brain as well as getting the blood all the way from the bottom of the extremities (feet and legs) back up to the heart and lungs to be recirculated, so I'm not surprised to find that the heart rate is higher for the walk than it was for the gym workout.

To test the theory try doing a high intensive workout in a more upright position, intensive chin up, vertical leg lifts, skipping (with rope, you might get weird looks if you do it school girl style, but that's up to you 😉 ) Step ups (using steps) Jumping Knees to Chest, Burpies etc.  Then see what your average heart rate is compared to your usual workout.

[Mukluk4]

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@Ukase wrote:

I have been doing a modified cross-fit workout the past few months. 

Today, I rowed 100, 200, 300, 400, 500, 400, 300, 200, 100 meters - all rowed as fast as I could go. 

Squat, then lift 30# overhead, X10

Row 100 meters as fast as I can. 

Then do 10 push-ups.

Immediately after, Squat, then lift 30# overhead, X10

Then Row 200 meters ASAP, 

Then do 20 second plank. 

Then Squat, then lift 30# overhead, X10

then row 300 M, then curl 30#'s 30 times. 
Then Squat, then lift 30# overhead, X10,

Then row 400 Meters, then do 40 Mountain Climbers (get in a high plank, then alternate bringing legs up to chest) 
Then Squat, then lift 30# overhead, X10
Then row 500 meters, and do 50 lunges, each leg. 

Then repeat, but go backwards - 400M, 300M, etc. with the same exercises as above.
This workout took 52:24 minutes, burned 449 calories, with an average BPM of 110. 

This afternoon, I just went for a simple walk! It took 48 minutes, and according to my Charge HR, I burned 575 calories, with an average BPM of 129! 
 

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What are your rest intervals between your lifting?  Your walk is a consistent exercise that doesn't have any real peaks and valleys in your HR which would show a higher average HR.  Your interval training will have very large peaks and valleys which would show a lower average HR.