@jovi45 Those spikes are natural in all likelihood. As you stand from sitting, your heart must work harder to get blood from further below your heart back up to your lungs. You will spike just standing from seated. Then, if you begin to move around, maybe use your arms also, there is more 'work' being done, and your heart rate will climb further. This is both desirable and normal....it helps you to function those ways. What would worry you is if your 'spike' goes past 135 or so, maybe over 145, just walking casually or even when seated and calm. There is only a possibly disordered heart that would need a rise in HR to the 140's and higher to let you walk to the kitchen. Or a heart in arrhythmia, such as in the case of POTS (postural orthostatic tachycardia syndrome), or maybe in atrial fibrillation (AF). I don't see how you can have an arrhythmia with an HR around 125 when you are moving about. I could be wrong, and I'm also not medically trained. The thing to do, when you have symptoms, or see that your HR is above 125 when just doing normal stuff, is to take a Kardia or Fitbit reading, and then look at its graphical representation, the one that looks like a real ECG. Either device 'should' be able to upload the file to an app where you can see what the squiggles look like. Any arrhythmia will either be too fast, or there will be a nasty mess to look at, including no P wave and the highest peaks don't have the same distance...they're spaced out randomly. That would be AF.

The Holter can only record what really happens when it is on you recording. If you take off the leads and turn it in, and driving home you have a short run of AF, that's a miss. Your Fitbit may have been wrong, but it may have been right. You should have a record still on it of that detection. See if you can find it, upload it to the app, and look at it. Show it to your doctor.