I have a basic drugstore pulse oximeter. I know my oxygen saturation sometimes falls (it's too intermittent to predict when). I don't bother to check it that often, but I decided to wear it this morning while I did some light exercise of walking on an elliptical machine for ten minutes. At first all was good. My O2% was 97 and heart rate 103. Then the O2 began to fall. When it got down to 93, I paused for a moment and let it climb back up to the upper 90's. I did that two or thee times. I wasn't paying too much attention to heart rate because it wasn't too high or anything. At one point my O2 fell down to 89% and I realized something that struck me as strange: My heart rate was also falling. It dropped down to 71 (before I paused my exercise). From my perspective it seemed like my oxygen dropped first and my heart rate followed. But I could be wrong Shouldn't the heart rate increase when O2 drops? Does anyone else find that they have weirdly intermittent oxygen saturation problems? Just to add to the strangeness of my situation; after pausing for a couple moments, everything normalized and my O2 stayed in the mid to upper 90's for the remainder of my little workout. I would welcome any theories on what might be causing the problem.