Accuracy of calories burned while biking

[nscrbug]

I just wanted to post an update. So this weekend, I changed the battery in my HR strap (even though I didn't think I needed to), picked up a bottle of HR electrode gel and applied it to the HR strap, and took a manual pulse to see if it was close to what my Garmin was showing right before I set off on my ride. My HR was sitting right around 75-78, just futzing around getting on my gloves and so forth...which was right on target with what my manual pulse reading was. So, I established that the HRM seemed to be working properly at the time. I also double-checked my profile on the Garmin, and made sure that all the data was entered correctly - ht 5'6", wt 157lbs, Female, 44yo, activity class = 9.

After 3 consecutive days of riding, the results of my HR/calorie data were the same as before. On Sat, my avg HR was 101; on Sun, 109; and today, 108. Calorie burn was 888 (65 miles), 1,147 (83 miles), and 551 (43 miles) respectively. I don't know, it just seems weird that I cannot seem to get my HR up at all on the bike. I can safely say that I have NEVER even come anywhere close to hitting my MHR while riding. Is it possible that I just have a freakishly low HR? I normally don't wear a HRM at the gym, but now I am curious to see if it's that low during any kind of activity.

Don't know if this matters or not, but I do remember last year during a routine colonoscopy I was hooked up to a monitor and I kept setting off the alarms on it because my HR kept dipping below 40....freaked out the nurses. Maybe I just naturally have a lower HR? I don't know....

Linda

[DarcyInOregon]

The only other thing I can think of is your cycling position, can it be moving the chest strap away from contacting with your flesh? I can't wear a chest strap on the spin bike at the gym because some of the positions interfere with the chest strap, and maybe it is the same for you on your bike.

Regarding the low heart rate, the people I know with low heart rates during cardio exercise are on heart medications. I also chatted with a female cyclist a few years ago, who had transtioned to the bike from long distance running, and she couldn't get her heart rate anywhere near her max rate on the bike, but I am sure her average rate was over 120. So if you are not on heart meds, maybe you are super fit from another sport and the bike is too easy for you, or perhaps you need to do more miles of steep climbing?

Yesterday I biked an event metric. I looked at the Garmin data of a training group friend who did the metric too. When climbing the nasty hill, his heart rate was around 180; my heart rate was around 140, and that is a huge difference, though my max is only 165-170. But when I looked at the other data, his cadence was 80 and my cadence was 60, his speed up the steep hill was 8 mph and my speed was only 6 mph. He was able to push harder because he is a male or more fit, and got a higher heart rate due to more exertion. On the other hand, at the top of the hill was this one male cyclist who was younger than everyone in my group, and he was off his bike gulping in air like a landed fish, looking like climbing that hill just about killed him.

If your heart rate remains low when climbing real steep grades and you are exerting yourself fully, then my suggestion is see your doctor and make sure you are heart healthy. If your heart is fine, then guess you shouldn't worry about it.

[goldfinch]

Too many possibilities. You can also have depressed heart rates from fatigue and overtraining. (As well as elevated rates--can go either way).

A good time to measure your resting heart rate is while you are still in bed, right after waking up.

[nscrbug]

The only other thing I can think of is your cycling position, can it be moving the chest strap away from contacting with your flesh? I can't wear a chest strap on the spin bike at the gym because some of the positions interfere with the chest strap, and maybe it is the same for you on your bike.

Regarding the low heart rate, the people I know with low heart rates during cardio exercise are on heart medications. I also chatted with a female cyclist a few years ago, who had transtioned to the bike from long distance running, and she couldn't get her heart rate anywhere near her max rate on the bike, but I am sure her average rate was over 120. So if you are not on heart meds, maybe you are super fit from another sport and the bike is too easy for you, or perhaps you need to do more miles of steep climbing?

Yesterday I biked an event metric. I looked at the Garmin data of a training group friend who did the metric too. When climbing the nasty hill, his heart rate was around 180; my heart rate was around 140, and that is a huge difference, though my max is only 165-170. But when I looked at the other data, his cadence was 80 and my cadence was 60, his speed up the steep hill was 8 mph and my speed was only 6 mph. He was able to push harder because he is a male or more fit, and got a higher heart rate due to more exertion. On the other hand, at the top of the hill was this one male cyclist who was younger than everyone in my group, and he was off his bike gulping in air like a landed fish, looking like climbing that hill just about killed him.

If your heart rate remains low when climbing real steep grades and you are exerting yourself fully, then my suggestion is see your doctor and make sure you are heart healthy. If your heart is fine, then guess you shouldn't worry about it.

I did a steep but short climb on my ride this morning. I was monitoring my HR throughout the climb...my HR peaked at 131 (which also happens to be my max HR for this ride), and this is a very challenging hill for me. I have to ride in my absolute lowest gear...my speed up this hill is about 7mph, if that, so cadence is sure to be low as well. As for the possibility of my strap being moved while riding...I think it's unlikely. I generally have to "peel" the thing off me when I'm done, so it pretty much stays put once I put it on.

ETA - not on any heart meds

[Bike Chick]

Linda, I just caught this thread but wanted you to know that I have a Garmin 500 and I have been having the same issue. We time trial on Tuesday evenings and without the hrm the Garmin says I burn around 550 calories in a 10 mile hilly tt with an 18 mph average (which I think is close to accurate); with the hrm the Garmin says I burn 225--usually cuts it in half. DH has a Garmin Edge 305 and his heart rate records in the 500-600 range for the same tt. I think it has something to do with the Garmin 500.

[Catrin]

I do not have a Garmin but have heard from others that the Garmin 500 does seem to be prone to reporting lower heart rates and under-estimating calorie useage.

[OakLeaf]

I'd suggest stopping at the top of that killer hill and taking a manual pulse.

[Velocivixen]

To original poster: Why do you want this information? Training purposes? To gauge how much to eat? Just for kicks? Numbers nerd? I'm curious.

I use a Polar FT40 to see my calorie burn for every activity (fitness) I do. I don't eat more or less based on calorie burn. For me it just ensures that I get consistent calorie burn each week for fitness.

[nscrbug]

I do not have a Garmin but have heard from others that the Garmin 500 does seem to be prone to reporting lower heart rates and under-estimating calorie useage.

Based on what Bike_Chick posted above, I'm starting to believe this myself.

[nscrbug]

Linda, I just caught this thread but wanted you to know that I have a Garmin 500 and I have been having the same issue. We time trial on Tuesday evenings and without the hrm the Garmin says I burn around 550 calories in a 10 mile hilly tt with an 18 mph average (which I think is close to accurate); with the hrm the Garmin says I burn 225--usually cuts it in half. DH has a Garmin Edge 305 and his heart rate records in the 500-600 range for the same tt. I think it has something to do with the Garmin 500.

THIS!!! The first few times that I used the 500, I actually forgot to wear the HRM. Yet the calorie burn that was calculated for those rides, was nearly double what it is on rides when I DO wear the HRM.

Linda