HR and BG

[helli]

I was lucky to be given a heart rate monitor for Christmas and have been analysing my heart rate whilst at the gym.
I’ve been thinking about what kind of data I would like to compare with my heart rate such as power output, cadence, resistance, … and I’ve wondering if there is any correlation between my heart rate and my blood sugars. Could I predict a hypo my watching my heart rate?

At the gym this morning, I was pushing myself on the cross trainer and trying to reach my “functional threshold” heart rate (the highest rate I can maintain). However, my heart rate would not rise beyond about 70% of what I achieved last week. I tried to increase my cadence. I tried to increase the resistance. But all that would happen was that I was getting out of breath but my heart rate would not rise.
Then ….
Beep beep beep beep. My CGM alarm went off. My BG just dipped into hypo realms.
So, for me, a high heart rate is not indicative of a hypo. It is almost the opposite.

Anyone know what is going on? Why do I get out of breath but low heart rate with a low BG?

I am just curious.

 

[Inka]

I’m not sure @helli but sometimes I feel I’m having an asthma attack (I start feeling slightly breathless) and it’s actually my blood sugar going low. I don’t know if that similar to what you’re describing?

I’m not sure why your heartrate didn’t rise. Perhaps it was some kind of energy/glucose preserving mechanism? I’ve had the very fast heartrate with bad hypos in the past, but I’ve also had a scarily slow heartrate with hypos, so maybe it varies?

Out of interest, what heart monitor do you have?

 

[everydayupsanddowns]

Really interesting observations @helli

When I got a FitBit I initially wondered whether I would be able to draw parallels between steps/activity levels and doses and insulin sensitivity (plus hypo risk) - but I’m not sure I ever really found anything conclusive.

It was easier to spot the changes in insulin needs for me when I was gym going and took breaks when the kids were off school. Anything longer than a week and my doses would reliably and fairly predictably need adjusting.

 

[helli]

I’m not sure @helli but sometimes I feel I’m having an asthma attack (I start feeling slightly breathless) and it’s actually my blood sugar going low. I don’t know if that similar to what you’re describing?

I don’t think it is quite asthma attack like. But as I don’t have asthma I maybe wrong. It’s like when walking up a steep hill and getting out of breath but I feel it earlier than when not hypo.

Out of interest, what heart monitor do you have?

I have a Wahoo heart rate meter. It’s one on a strap that wraps around my chest. For me, that’s under my bra.

 

[SimonP]

I find I can't maintain high (for me) power (it's all relative!) on a bike when I have low BG, but I can almost always keep plodding along.

I've read that when fatigued cyclists' max heart rate is reduced, and apparently it's one way of telling whether you're overtraining to see whether your heart rate rises as high as expected for a given activity. I'm not quite sure how this works though as I'd have thought being unable to achieve a sufficiently high heart rate would limit performance too - I will have to do some digging. I wonder if a similar things happen when blood glucose is low, I assume it would have a similar effect to overall fatigue.