Irregular Heart rate on Treadmill

I am 63 and exercise moderately (40 minutes walk/jog) 4 days a week. Lately I noticed when I first start walking on the treadmill, it can't seem to get a reading on my heart rate unless I straddle the belt and stand still. The reading then is typically 85 or 90. When I start jogging and finally get a reading my heart jumps up to 176 . If I continue jogging on the treadmill it comes down to 120 -130 range. Is this a problem to be concerned about?

[Jerry_NJ]

Have you been checked for irregular heat rate?  Atrial Fibrillation, a heart condition that strikes many as they grow older, mine started around your age.  AFib will make it difficult to get a regular heart rate, at rest or when exercising.  Of course some people who have AFib have it off and on, not all the time.  Some may have it when exercising, say, but not when at rest.  This would be harder to detect, I think.  I have AFib all the time...and it also contributes to a higher (ventricle) HR whatever I'm doing, or not doing.  For example, in the recent past when I had sinus heat rate my heart rate at rest would be about 60 bpm.  Now with AFib it is in the high 70s to 80s.  

[acemot]

How do you get checked for Atrial Fibrillation? I just had a resting EKG prior to some minor surgery and the doctor said it was fine.

[Jerry_NJ]

An EKG will show AFib, if you are in it at the time.  Some, maybe most, people go in and out of AFib.  I am in AFib 100 % of the time.  While it isn't scientific, I can tell I'm in AFib by watching a heart rate monitor, I have a Polar exercise monitor.  My HR jumps around, not wildly, but jumps, at rest maybe 76 for a few seconds, then 84, then 75, then, so on.  If I get up and walk around I get a similar result but the rates higher, 100, then 90, then 115....

I think a doctor can tell AFib via a stethoscope - and I too can hear the irregularity with a stethoscope.  I can not feel the irregularity in my chest, nor with an attempt to feel my pulse on my wrist.