# Can 20 bpm mean so little?



## lonelobo (Sep 17, 2009)

Vital Stats:
53 years old
296 lbs
long time cyclist, ride for years/quit for years, repeat

I've been riding seriously now for a few months and just recently started using a Heart Rate Monitor just for grins. I've been working at getting my average speed up and now it's about 14 mph for a 15-20 mile ride, pretty much flat OR with moderate hills. According to my HRM I stay in the 140-155 beats per minute when I'm riding steady and for me, relatively hard. I usually keep myself breathing hard on the flats and REALLY breathing hard on the hills. 

So, today, for the very first time I decide to take it really easy and just spin with almost no force except on the hills where I just kept downshifting. A couple of times I would exceed my target threshold (according to my HRM, that's around 146) Several times I got out of range on the low end (108 or so). But my average was 120-135 bpm.

So when I got through and looked at my AVG. speed it was 12.2 but I felt I was crawling when I was riding. At my regular AVG. 14 mph I feel like I am balls out. I am astounded that a difference of 10-20 beats per minute amounts to less than 2 mph difference in my average speed. AND, that less than 2 miles per hour difference can feel so huge on the bike. 

So, my question is, am I totally delusional or does this seem a normal exertion/performance ratio?


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## Andrea138 (Mar 10, 2008)

Sounds normal to me.


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## California L33 (Jan 20, 2006)

It's that last little bit that's torture- a bit like opening those two really big barrels on a carburetor and finding you can only go from 80 to 100MPH. Good for you for riding, but at 296 lbs and 53 years old does your doctor know what you're doing? He'll probably encourage you, but still... If you're riding for weight loss (hopefully and fun) longer low intensity rides may be better. Check out the Clyde forum on MTBR- link at the bottom of this page.

Edit: Editing this for clarity- I don't mean that I hope you're riding for weight loss. That's your business. What I meant is that I hope one of the reasons you're riding is for fun regardless of any other. Big or small, hard ride or soft, cycling is a blast.


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## Alex_Simmons/RST (Jan 12, 2008)

There is a cubic relationship between power and speed.
Those 2 extra mph require an extra 40+% more power.


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## lonelobo (Sep 17, 2009)

*Yowza*

Thanks for the responses! In a way, your explanations make me feel better. At least I know that I'm not crazy...at least not due to THIS phenomenom. And yes, my doctor is aware that I am doing this. I quit smoking up to 2 packs a day three years ago and now I'm determined to lose at least 80 lbs. but changing my eating habits is proving to be a bit tougher than I thought. 

My blood pressure is on the low side, resting heart rate is approaching the 40's, and all my cholesteral stats are good with the exception that my Tri's are a bit high but coming down fast as I cycle more. Life is GOOOD..... thanks for your encouragement. I will try slower and longer at least once a week.


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## team_sheepshead (Jan 17, 2003)

Alex_Simmons/RST said:


> There is a cubic relationship between power and speed.
> Those 2 extra mph require an extra 40+% more power.


Alex has it right. But also look at it this way: Don't get caught up in absolute numbers (12.2, 135 bpm, etc.) Look at the relative numbers:

The upper end of your heart rate range decreased from about 155 bpm to 135 bpm. That's a decrease of just less than 13%.

Your average speed decreased from 14 mph to 12.2 mph. That's a decrease of.. wait for it...just less than 13%.

Bellissima!

Now, I doubt you're going to find a direct relationship like this all the time; it's probably random. But it would be interesting for you to go out and test it to see if there is such a direct relationship between your heart rate and your avg. speed.


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## muscleendurance (Jan 11, 2009)

20bpm is huge. Its the difference between moderate/tempo and threshold for me anyway


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## Donzo98 (Oct 1, 2008)

muscleendurance said:


> 20bpm is huge. Its the difference between moderate/tempo and threshold for me anyway


and so is 2mph average difference.... try to increase from 14mph to 16 mph and see how hard that is...


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## California L33 (Jan 20, 2006)

lonelobo said:


> Thanks for the responses! In a way, your explanations make me feel better. At least I know that I'm not crazy...at least not due to THIS phenomenom. And yes, my doctor is aware that I am doing this. I quit smoking up to 2 packs a day three years ago and now I'm determined to lose at least 80 lbs. but changing my eating habits is proving to be a bit tougher than I thought.
> 
> My blood pressure is on the low side, resting heart rate is approaching the 40's, and all my cholesteral stats are good with the exception that my Tri's are a bit high but coming down fast as I cycle more. Life is GOOOD..... thanks for your encouragement. I will try slower and longer at least once a week.


In terms of weight loss, conventional wisdom says (and I'm not an exercise physiologist, so I can't say it's 100% true, but it seems to make sense) that short intense workouts cause your blood sugar to plummet, and leave you ravenous and exhausted. But, it takes time to convert fat into sugar to power muscles, so you're probably already eating before that happens. If you do long low intensity workouts, your blood sugar starts to drop, and your body reacts by converting fat to sugars. By the time you're done you're still hungry, but you're not as hungry, and you've already burned some fat.


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## rodist (Sep 2, 2005)

*You numbers are correct*

Those numbers seem dead on. I am 50 and average 147 BPM / 18.5 MPH for a 3 - 4 hour ride. Adding 20 BPM puts me just over my Lactic Threshold and I can sustian that for about 50 minutes to an hour. My speed though is around 23 - 25 at that heart rate.


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