Big drop in max heart rate when becoming fitter?

Hi everyone, I have a situation i’m quite clueless about.

3 months ago I started triathlon training again after a hiatus of serious training of 2 years because of work, injuries etc.

My training consists of only building aerobic miles, and especially in running being very carefully.

In these 3 months, I’ve seen a very big drop in heart rate at the Same pace or power output and have seen decent FTP gains from 275 to 310 watts. I used to run 5:10/km at HR 155,now it’s 135 (using Barry p plan of 6 easy runs per week). Used to ride base zone 2 miles at 125-145 bpm and now 130-135 max for 70% ftp.

However, I’ve noticed that I can’t get close to my previous max heart rate any more. Few years ago, I would do my 20 min FTP test at an average HR of 180. Now during my ramp test I can’t get over 175…last week at the end of a hard 4h ride (IF 0,8) I did a climb all out, 17 min at 320 Watt and my average heart rate was only 160, max HR 172… Today I rode a small segment outside, 3 mins all out with a max HR of 173. 2 years ago I could go to 189 at that segment (although I rode my best time ever today on that segment).

I would Guess that maybe I’m fatigued but I feel very good and my resting HR has dropped from 55 to 50 over these 3 months.

Could the dropping of max HR be a result of my pure lsd zone 2 training? Or Could something Else be going on? Am I overtraining? The fact that my max HR dropped so much makes me feel like something is not right.

Thanks in advance

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Curious to see what others say because I’ve experienced the same situation. My max heart rate last year was 195 during some strides at the end of a run. I was not in good shape. The highest HR I’ve seen since then is 185 during a ramp test, and maybe 180 during an all out 30 second sprint trying to KOM a strava segment. I think my heart is stronger than my mind now. I can’t push myself hard enough to get back to that max HR.

One possibility

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Might also be early signs of overtraining?

Could be that your general base aerobic fitness level is a lot stronger than your muscular endurance. I’m in the same boat as you as I asked this question last week.

I’m 31 years old and even during all out efforts I rarely see my heart rate go above 160 on the bike

I’ve had very similar effect when I was “training” 15+ hours per week mostly in “Z2” - commuting by bike (twelve 1hour+ rides per week), some running and doing a lot of walking at work. Actually your values (running HR at pace, resting HR) are almost the same as mine from that period.

I think what you see is not really a change in HRmax, What you see is a totally different HR kinetics as reactions to the effort.
For myself i notice often a dramatic change in the lower and middle gears. Today for example i rode a segment with IF 0.86 with only 75% HRmax,. In winter i may have IF of 0.7 with the same HR.
In winter is no problem to ride with 75% HRmax several hours, now I can’t.

On the other hand in case of competitions i reach pretty similar HRpeak values, the absolute end of the scale seem to be the same.

Intervals is in between, I see here a moderate drop of average HR that is sustainable for a given series. If i push the last minute as hard as i can, the HRpeak is pretty much the same.

A couple of issues right out of the gate. 1. MaxHR declines gradually with age - probably about 3 bpm over 5 years. 2. Running maxHR tends to be slightly higher than cycling maxHR. Put those 2 factors together, and you could definitely expect to see a cycling maxHR 5+ bpm lower than what you might have achieved running a few years ago.

But more fundamentally, your recent training seems to be have aimed very much at building your aerobic base. This is a good thing, but it probably means that at the moment it is your legs that are the limiter during hard efforts, not your cardiovascular system. As you progress to the Build and Specialty phases and add more intensity (and more muscular endurance work in particular), your legs will be able to last longer during hard efforts, and thus you will see a higher maxHR during those hard efforts.

+1 for good aerobic base. I would just look into overtraining if suddenly RPE goes sky high and motivation disappears.

Just to be curious: I googled BarryP and I got the idea of 6 runs/week with an ratio of 1:2:3. The original post I found stated that the long and mediums runs should be hard and not easy. Did you adapt the plan yourself or is there any further reading about that?

I’m certainly hoping it’s just my aerobic base being good and not overtraining or something strange going on with my heart. I feel good and even when pushing the pace I can keep breathing quite normal and feel recovered a few mins later. So I guess muscular endurance is holding me back right now.

Re the Barry P plan, I’m in Base phase so my runs are recovery pace, long run pace and easy run pace (mcmillan calculator). I’m quite injury prone in running (built like a sprinter, not a distance runner. Damn you, shin splints and stress fractures!) so I’m very slowly building mileage up first. Probably I’ll only start increasing pace or doing workouts in september.

Still quite weird that a few years ago I was in top shape and could reach HR 190 during a short effort and now I can’t. I’m only 25 btw.

But I guess as long that I’m feeling good and keep improving, I have to trust the process.

It is fatigue. Rest a week by doing almost nothing and try again. It doesn’t mean you can feel “rested”.

I have similar experiences. I did yesterday a 5’ max test where i hit an all time high but was nowhere near my heart rate max.

If you improve your lactate curve by doing low intensity work you will see a drop in hr in all but your hardest efforts. I have noticed the same thing, the fitter i am the harder it is to reach max. Mostly because now my body needs to go harder effort and longer duration than before to approach that and it can take i bit of searching before that point is discovered.