I don't know why the data get posted as crazy as that above?

I ran the same trail loop, same time of the day, same direction, same weather etc as two days ago.  However, something interesting happened on the second loop. My HR went pretty high on a few occasions. It maxed out at 205 bpm. It was not the Garmin's fault - I could actually feel that my heart was working hard. That's what made me look at the wrist watch and that's when I how high the HR was. It stayed in the 190s and 180s for a while - then it went back down in the 140s where I am very comfortable but a little later it went back up into the upper ranges.

I must have been anaerobic during those parts of the run?!

Why did it happen? I wasn't running particularly hard or fast - it was hilly and a little uphill but not any more than it was 2 days ago or on the first trip around the same loop. 

Should I have stopped and walked the HR down?

I decided not to stop but to keep running and to see what would happen. How long it would take before it would go down etc.

It makes me wonder how high my HRmax actually is. Though it felt uncomfortable to feel the heart beat in my throat/chest I was not dizzy or breathing particularly hard. My legs were working fairly hard.

Please, let me know your thoughts on this and if you've experienced similar things. If you are not in your pure below MAF mode how do you react when your HR gets very high? Do you allow yourself to run in the anaerobic zones near HRmax other than in those particular workouts when you aim to become anaerobic?

It could be a blipout by the Garmin. Or perhaps you were running fast enough to get your HR that high. If it is not either of those, then consider that your heart might have some temporary problem with its pacemaking.There have been some members of this forum that have had a heart-racing problem during running. I'm not trying to scare you, it's just that you should know if you are running hard enough to produce 200+ beats on the HRM at age 49.

Next time the Garmin does that, stop and take a ten-second pulse on the wrist. Multiply by 6. See if the pulse is in the ballpark. Then the Garmin ain't lying. Try to eliminate the possibility of a heart problem.

 In terms of your last question. Whenever I train above MAF, I  still use a HRM and have specific HR's that I'm trying to hit. I will slow down or speed up to keep to my plan. I might be doing Fartlek and I use a zone of 88-90% MHR. I try to stay in there. Or a marathon race pace run, where I'm following a graduated HR plan from 160-175 bpm (for example) for an hour. I try not to exceed the plan. I always have a specific reason for a run, and try to stick to the purpose. I have a specific purpose for this current base period I'm in and I try to stick to it, even if I have to crawl to keep my HR down. It's all about knowing what you are trying to do, why, and either committing to it or not.

--Jimmy

I had a similar experience today. My heart rate, according to Garmin went up by 20 bpm within a few paces. I

had just glanced at it to see126, and seconds later it was 146 on level ground, same pace. I't's not often, but

I've seen this on several occasions. I'm guessing it's a Garmin issue, but like Jimmy suggests, quickly

checking your own pulse should put you at ease. Likewise, my MHR is considerably above the classic 220

minus age. (Thankfully).. I need all  the heart rate "reserve" I can get!

May I suggest a simple program for screen capture? It is fairly easy software to use/understand (the only kind I

can tolerate). It's also freeware! Take a look at a program called "MWSnap3" from http://www.mirekw.com/ (You

should see MWSnap3 listed under the "windows freeware" link) It doesn't do a whole lot other than capture the

screen image, but when dealing with the Garmin interface, that can be a start. (Never could quite do much with

Garmin data management)

lg

The above graph is from my Garmin; picture of my HR = blue, and the corresponding elevation = green.

Thanks so much for responding to my post. I had to hurry out of the house after responding to Jimmy and have not seen the rest until now. I have been worried all day long that something is not quite right in the state of Denmark. I appreciate knowing that it is not uncommon to have a HRmax higher, substantially higher, than the 220-age formula. Unfortunately, I don't think the Garmin is to blame fore the readings today. I think they are a picture of what went on with my heart rate today. I am a little concerned about it. I have talked to my husband about it today so he now knows what is going on with me, my heart, and my running. I think I will stop running if it happens again to see if my body can more easily get the HR back to normal if I don't keep running. If it happens frequently I am going to see a medical professional about it. It would not concern me so much to see high HR readings if I had excerted myself with a hard 5K race pace or hard hill work etc but today I was running an easy run and basically cruising at a moderate HR level and pace. 

Mile 7-8 is a cooldown run. After 8 miles I am just walking and then driving before I noticed I hadn't pressed the stop button.

Flower, the graph wasn't showing and I think this is the one you were linking to.