Weights training app

[Rekten]

Not sure if I should let it run during my weight training time, or hit pause after every rep? Is it to track your entire time in the gym or just durring reps?

[Venkats]

I guess it will be personal preferences. I do not use Weights mode when performing pure weights training, partly because estimated / reported calories is grossly inaccurate. The tracker estimates calories based on heart rate while a significant part of energy originates from local muscle cells involved in the contraction. In my experience, any time you lie down on the bench or floor, heart rate may not increase much. Any time you have a axial load, the load itself can cause thoracic pressure changes resulting in elevated heart rate. I find more use case for the timer functionality (precisely timed sets) and once you are in weight mode you cant access timers. However for high intensity type workouts (I am a crossfitter) I do use workout mode for tracking intensity of the workout.  I actually wear two watches during weights training. The exercise zones and active minutes will be automatically computed anyway.

[WavyDavey · Accepted solution]

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@Rekten wrote:

Not sure if I should let it run during my weight training time, or hit pause after every rep? Is it to track your entire time in the gym or just durring reps?

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Hi @Rekten,

While you can pause it during the workout, I would not recommend that for weights.

One reason, is the calorie counts will be far too low that way. Your heart is still working between reps and sets, and you'll want the Fitbit to capture that data.

Second reason, is the length of the workout will be off if you pause the tracker during exercise. Because rest between sets is usually longer than the time it takes to complete reps, an hour workout would look more like a half hour with pausing.

Third reason, it's just easier to let the tracker run until the whole workout is over. I start the tracker when entering the gym and stop it on the way out. Others might start it after their initial warmups, etc.

[bbarrera]

Weight lifting is an anaerobic exercise. Calorie estimates using HR are based on aerobic exercises, and more specifically the linear relationship between HR and calorie burn when HR is between something like 60-80% max HR (I forgot exact percentages). So the Fitbit calorie estimates are not particularly interesting. Really all you get from Fitbit tracking is the duration of your weight lifting session, maybe some active minutes, and a check mark on your Fitbit exercise calendar.

What you really want to track during a lifting session is the amount of weight, sets, and reps. That is not possible today with any Fitbit.

[Venkats]

Relationship between HR and calorie is linear between 40 to 70% of Vo2max. It is linear if the energy is primarily expended by the Tri-carboxlic acid cycle. HR is linear with O2 uptake. The assumption in estimation is O2 is consumed and CO2 is released during energy cycle. O2 is not consumed in anaerobic system as it is either lactic acid based or creatine phosphate based. Volumetric differentiation is measured to compute enery expense. Certain cardiac arrhythmias  such as supra ventricular tachycardia can result in a person spending significant time above 90% Vo2max. This is not fitbits classification of peak. The peak intensity which is universally accepted is above 90% of VO2 max where, in a healthy person sympathetic nervous system takes over to make the person slow down or leads to syncope.

It is really not all that useful in measuring HR during traditional weight lifts. 

[bbarrera]

@Venkats thanks! Just found one of several bookmarks I have on the subject.