Cardiovascular system works better than muscles?

I noticed something in my training and I wonder what the concensus is about this:
Started cycling in Dec 2020, bought a KICKR in September 2021 and started training in SYSTM in December 2021. All numbers went up, of course, but what I notice now is not really an increase in power (newbie gains don’t last forever) but I see 2 things:

  • my average heart rate is going down
  • my muscles blow up before my heart. Often I have to give up pedalling because my legs are toast, but my heart is still quite some beats away from HRMax, while 2 years ago it would hit that HRMax before I had to bail out. I have the same outdoors on climbs.

So, my questions:

  • is it possible that my cardiovascular system has become “stronger” than my cycling legs, e.g. that I have cardio reserve but no muscle reserve?
  • is it possible that my max HR simply went down by 5-7BPM over the course of a year?

To give some numbers: when I started out I regularly hit 173BPM. After a year of cycling I actually hit 178BPM a few times. Nowadays it stops around 168-170


Yes I’ve seen this before. Are you doing Full Frontal regularly? Your rider type may also have changed. Also, VO2 or MAP power acts as a ceiling on FTP.


Because we are on the internet you of course can’t see me, but “crazy” is not written on my forehead, so no :smiley:

I did 1 4DP when I started (when I was naive and I didn’t know what to expect), and stuck to a couple of HM since.


Ok that should keep your FTP and MAP reasonably up to date.
Are you following one of the plans or just riding what you like when you like?

Currently doing a 3 week MAP block. But for me outdoor riding has priority, so if the weather is good I don’t do my training and I ride outside.

Something else I noticed: there is a hill nearby. I did a certain time on that hill in June 2021. I still haven’t beaten that time. The best I did was a couple of weeks ago where I did the same time I did nearly 2 years ago, but my average heart rate is quite a bit lower.

No real science from me, maybe the coaches have something, but I’ve noticed similar patterns – while I’m still making small strength gains, my HR/cardio efficiency are more much noticeable. And like you, my legs tend to give out before my HR, which was the opposite when I started training.

With maybe 6-7 months in between two FFs, my cTHR dropped 2bpm, but my power numbers went up. And I almost never hit my max HR anymore when training. I’d say my max is above maybe 195, and when I’m training I infrequently crack 190. On the road I might, if I really give it my all on a short climb, like this morning when I was trying for a new PB and hit 196. (Got the PB!)

I think our hearts are consistently getting more efficient, while the muscular gains are not as big, like you said. And, max HR does lower with age, like you implied, though probably not as much as 5-7bpm, I think it’s usually around 1-2.

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Same experience here. Forgot to mention: resting HR also went down of course.

Adjust the dates slightly and it’s my life you’re talking about!

Very much same experience where I’m finding myself with spent legs, yet HR nowhere near the max from couple of years ago. Strava is a really good tool to remind one how (un)fit they are. Thankfully I’m finding myself equalling or bettering my Strava times with consistently lower HR.

This is likely an interesting result of several things.

Firstly, it could be to do with an internal mechanism called the respiratory metaboreflex. This is where the respiratory muscles get fatigued, so to maintain breathing capacity, the body redirects blood flow to the respiratory muscles and away from the legs, increasing the perception of fatigue in the legs. Core work can help strengthen the respiratory muscles and delay this process, meaning more oxygen for the leg muscles.

Secondly, critical torque. When we produce power (watts) we need torque (Force) and angular velocity (RPM). Often, the limit is our ability to maintain torque production, which is why RPM has to increase or power output drops. Great ways of improving this are cadence work at lower RPMs, and also strength work off the bike.

Finally, regarding HRmax, this is something that is not uncommon, for your initial HRmax to increase, and then as you get fitter and your stroke volume increases (more blood per heart beat pumped), your HRmax and working HR for different intensities starts to drop. When I started I could hit 203 BPM, this then dropped to 185 max generally but only when fresh and rested. Dysfunctional overreaching and excessive fatigue push it down to 170. I would say your drop is well within normal regions so nothing to worry about.

Hope that answers some questions and helps a bit


Interesting. Just for completeness: I do core training twice a week and leg strength training twice a week, for quite a while now (longer than I have been cycling :slight_smile: )

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That’s good to know, in that case the low cadence work on the bike may be a useful addition to add, some high cadence drills can also help improve pedalling efficiency and boost sustainable power

Thanks. I think I’m ok in high cadence drills. I can hit 170+ rpm for 60 seconds (my KICKR doesn’t register anything faster than that unfortunately) without any issues.

That’s impressive for a minute! I would say overall though, not to worry about legs going before HR does, as that is entirely normal as you get fitter

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Cadence? High cadence will blow up your cardio vascular. Low cadence will blow up your muscles. Optimal trained cadence will balance the two. Commonly, that’s around 90 rpm.

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When riding outdoors if I’m doing a normal ride, I ride at 90rpm. If I want to go flat out for an hour it will be around 100.

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Depends on the power output, torque levels, and critical torque. Which is why optimal cadence can be between 65-100 RPM. Working high cadence can improve muscle activation patterns and pedalling efficiency, low cadence can improve neuromuscular activation and recruitment

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Of course there are a lot of variables, but outside of higher grades, fit trained cycling enthusiasts (and better) in fast group rides, crits, CX, etc., gravitate toward 90+ rpm. And, SYSTM workouts just about always specify cadences of 85-95+ outside of specific high torque drills. Agree there are a few who have a lower optimum cadence, but they are few. If legs are giving out before the lungs, higher cadence is almost always the answer.