Upped my cardio, but lower HR?

Hi all,

I have a cardio/HR question. I have significantly upped my cardio in the past week and my HR (as noted on those finicky stationary bikes at the gym) is lower than it was about a week and a half ago. I realized I wasn't giving it my all and pushed harder and got my HR up to 140-150 for a couple days, but since then I haven't been able to get it higher than 130 and generally it is between 110-120. I almost doubled my resistance (5-7 to 8-10 if that means anything - I don't know what the max is), am biking steadily at 85-95 rpm and sweating like crazy. I was shocked to see that I could up my resistance so much and not find it that difficult, but I doubt I have really improved enough for it to show on my HR so quickly.

My PT said that if I'm at the same rpm and resistance, I am still working the same amount and it is likely the bikes that are giving me the wrong readings. But I've tried a few different ones, and checked once when it said I was around 110 and it was close. I don't have a HR band or anything and can't afford that and I know I'm probably overthinking this because all that matters is I'm working hard and improving. But I find it strange that I can't get my HR up at 95rpm and a higher resistance than ever.

Does anyone have any insight for me? Were the 140-150 readings the ones that were off? I'm pouring sweat and can't imagine that would be the case at 115 HR. Some info on me: I'm 27, f, 172 lbs and have begun exercising 5-7 days a week (including weight lifting every second day) since the end of July, before which I didn't do much at all. I was always very athletic until I was about 20 and other things kind of took over, including weight gain, where I got up to 200+lbs.

Thanks!

Your PT is correct in that the "same rpm and resistance" will give the same workout (power = torque * cadence). In theory, your HR will drop as you gain fitness. Sweating is an indication that your body temperature is elevated, which may or may not have any relation to your workload.

Are you verifying your HR manually?

I'm not verifying manually regularly, because I have to stop biking in order to feel my pulse. But I will check more often to confirm, thanks.

I have the same thing happen to me on occasion. With me it's typically lack of sufficient rest. I take a day or 2 off and am able to quickly get back to the elevated heart rates.

First those monitors on cardio equipment aren't the most reliable - due to chemicals ( sanitizers) they can ruin the conduction, then you have overuse and just other factors.  I had an elliptical and it wouldn't pick up my heart rate monitor but it always said my pulse was about 120 my HRM on the other hand would say 140!   

I also notice sometimes I feel like I have to be hitting 140+ on my HRM to look down and see it only says 120!  I feel like I'm working hard, I'm breathing heavy and sweating, yet the heart rate is not saying the same story.  I do have COPD though, and that sometimes effects the breathing factor so I can feel out of breath and sweating profusely but my pulse doesn't tell the same story.

As we get in better shape our heart rates don't increase as easily.  I can never get my heart rate a decent pace on a stationary bike cause my legs can't go that fast, but when I ride my bike I get a good workout but I am changing gears and inclines and such.

You could also go by perceived rate of exertion.  Can you talk?  or are you only able to answer with a grunt or a nod because you're breathing so hard.  

And yes, sweating is not a good indicator of a workout.  Medications, room temperature, amount of fluids you've had during the day can all effect how much one sweats.

Practice taking your pulse manually on your carotid artery on the side of your neck not on the bike and then try doing it while on the bike.  I am with your PT and the rest of the gang here that the HR monitor on the machine is probably not correct, and would go more with how you feel you're doing than what the machine says.  Good luck!