Can’t keep same HR in aerobic workouts
 

Greetings!

From the beginning of this year I’ve started building my cycling form using Zwift. I tried «Build me up». But soon realise that long effort at 3-4 power levels completely drain me out. My HR was steady at the beginning of such workout but rose to red zone in the end. I had to reduce difficulty just to finish the workouts!
So I went for 12 weeks «FTP Builder». I found it much easier.
Now I have 5-6 hour of trainings each week. But I’m facing the same problem: can’t keep same HR in aerobic workouts. Yesterday I tried simple (as I thought) TT Tune-Up - Aerobic 12s in Zwift. Everything was fine for 40 minutes: HR zone 2, same power. But in the last 20 min HR goes to zone 4. What’s wrong with me? Poor muscle endurance? Symptoms of health issues (lack of iron)? Poor hydration or nutrition? Or maybe nothing special: I should just keep training?

As you exercise your core temperature goes up, your body reacts and increases blood flow to your skin and in effect reduces the amount to your muscles. To keep the same flow to your working muscles your HR will have to go up. Similar to a having a higher HR when working out on a hot humid day. It's all relative. I ride an elliptical at times and do long steady state workouts on it. I get up to say 155 (my 90%) and hold there. Eventually my HR starts creeping up and I ease off the effort to keep it there. I've used a fan but I can't say it changed much for me but others say it helps. Hydration goes down during the workout probably adds to the effect.

Look into "VO2 Max" type training. Good benefits, if done well.

Improving Your Max VO2 @ Runner's World.

How to Increase Aerobic Fitness @ Live Strong.

An Update of Rowing Physiology (PDF doc) @ U.S. Rowing.

Effect of High-Intensity Interval Training on Cardiovascular Function, V̇o2max, and Muscular Force @ The Journal of Strength and Conditioning Research.


Back in the day, I did a lot of distance running. More than half our running was longer, somewhat-slower distance. Gave us a good "base" of aerobic endurance. However, for increasing our overall O2 intake, and for improving how long we could sustain higher-effort activity, it was vital to incorporate hard interval training as well.

On harder such runs, we'd often do hard 20-30 second sprints followed by a short recovery period (of ~1-2mins, tops). Occasionally, we'd do periodic max-effort 10 second sprints on such runs, followed by whatever recovery was needed. Done consistently across mid-distance runs, over the course of a few months, it could significantly improve our overall high-output ability. Increased oxygen uptake, decreased recovery times, improved overall times at that distance, etc. Can duplicate the concept in swimming, rowing, cycling.

Another variation: negative-split runs. Take a 5mi run (or row or ride), for example. Warm up, then start the run. Hit a given pace for the first mile. For the next mile, drop 10-20 seconds for the pace. For the mile after that, go another 10-20 seconds faster still. And so on. Continue until you're completely wiped, and can't improve any more. That run's done. But you'll find you've pushed your O2 and heart rate levels far beyond a typical run (ride, row). With sufficient rest, such training cycles done over months can yield noticeable gains.

Takes a lot of extra energy, to hit such performance goals in training, of course. Ensure your nutrition's up to par. Lots of good building blocks, vitamins, minerals. Ensure you're having sufficient complex carbs prior to such workouts, including during workouts if the duration is going to exceed your body's energy reserves. (ie, For runs <45mins, I rarely found I needed extra food, but with harder runs over an hour it was useful to eat a greater amount of protein/carbs prior to the run as well as a bit during. Vital on anything at the half-marathon or greater distance+effort.)

Be mindful of recovery and rest, too. If you're doing such training daily, you're simply going to keep depleting your reserves and won't be effectively rebuilding and repairing. The higher-intensity interval regimen is something we could do 2-3 times per week, in a week of ~10x training sessions. Done hard, it'd take 2-3 days of recovery before we'd be ready to do something like it again. With a good base of longer, slower distances, over time this helped us get faster, run cooler, with lower overall heart rate during harder efforts. But the recovery and rest times were key to rebuilding stronger.

I've duplicated this method in competitive swimming, in running. These days, I do it with rowing training in the gym, to a lesser degree on the treadmill. Though, for me, cycling today is an exclusively non-competitive, non-training type activity. The higher-intensity stuff comes on the rower and treadmill, these days.

You're inside. You're massively overheating. Very common.

Get more fans and/or stronger AC.

Thanks to all for your replies!

I’ll try to set more fans and use VO2Max workouts. Hope it’ll work.

Yup, heat will mess with heart rate and blood pressure, at least until we're heat adapted. This week I had my first 100F (equivalent, actual temp around low 90s) rides. My max HR peaked normally, around 160 bpm at around 90% effort (I'm 61 so that's about right for me). But my low HR never dropped below 120 during easy efforts or rests up to 5 minutes. And it was still 120 bpm, with BP around 140/90 for an hour after I got home. That's unusual for me. Normally my HR will drop to around 80 pretty quickly, and BP will usually be lower than my normal, around 100/60, immediately after a ride or workout.

So I'll just monitor my HR and moderate my efforts until I'm better adapted to summer heat. June is usually my tougher transition month and by July-August I'll be adapted.

The technical term for increasing HR at constant power over time is cardiac drift. Heat, hydration and fitness are a contributor but there is also the effect of the heart stroke volume decreasing over time. To keep the same blood flow the same as the heart produces less blood per beat, the pump must run faster. It is not completely understood why the heart does this. There is not a lot that can be done other than take it into account in pacing strategies. Hence if a runner uses heart rate to pace a race, over time, the pace will slow as the effect of cardiac drift takes hold.

However, riding inside is notorious for producing heart rate drift. YMMV.

That was my first thought also, cardiac drift, but OP sounds like he's got more going on than just that. Heat, hydration, lowered oxygen in his area if ventilation isn't strong enough, something like that. It could also be a matter of conditioning though.

I would want to compare indoors with an outdoors ride at the same effort and duration, to possibly eliminate some of the variables.

You heat up a LOT indoors on the bike. Without a good fan, durations and intensities can suffer.

Invest in either a decent box fan OR if you can afford a decent "blower". A blower is the thing companies use to dry out a room after flood damage. Looks like a big plastic turbocharger with an oval shaped outlet.

Other possibility is that you're overestimating your "ftp" or whatever value you're basing your workouts off of.

If you chose wisely, a workout should be a challenge but should still be able to be completed. That sounds very vague, but to an extent "you just know when you know".

If you're getting out of the zone in the last 5min of a 2x20 set......just finish and grit your teeth. If your finish point goal is like 165 bpm but you're at 175 bpm by the 10th minute, you calculated too high of a % to try.

Finishing all sets of a workout is more productive than bonking 1/3 of a workout all the time. If a workout seemed easy, add 5w next time. Or 10w.

I will say, a lot of the sufferfest and other stuff seems like a weird peppering of zones and intensities and durations and not very repeatable workouts all based around an ftp or "base value".

If I have some 2 sets of 3x3 and I can't do any of the 2nd set or can only get like 2 1/2 minutes...I can decide myself to back the power off next workout. Or, if I bonk the very last rep in the last 30 seconds........close enough.

Something about good ole intervals that's appealing. You can track progress and make modifications easier.

Well, I’ve tired a lot of things last weeks.

First of all, I moved to a cooler place of my apartments. Now I’m spinning in front of big opened windows at the evening (no sun). The temperature outside is quite low (15-20 C). I’m still using only one fan. Between long hard interval I take a break to cool down. Also I began to drink more water during a day and isotonic during a workout sessions.

I visited my local hospital and completed basic medical check. My haemoglobin is ok (but I didn’t check my ferritin level yet).

All of these didn’t completely fix my problem (but it’s definitely easier to spin now).
Here is my workout analysis from Strava. It was 3x10 min FTP intervals: https_monosnap_com/direct/HpULWRR6hHJG6MtE1iR0zCx9vX1H3y (sorry, I’m newbie at this forum. Can’t insert a link:( )
You can see how my HR rose at the end of 2nd and 3d intervals.

And here is analysis from the same workout but another athlete: https_monosnap_com/direct/xvuyuuGmCJQWed29hgCHDNXy2PM0ZJ
Almost same level through 3 intervals.

I already spent 118 hours on the bike this year doing different workouts. What do you think? All these symptoms caused by the lack of fitness level? I don’t believe that more fans will solve this issue :(

Can't comment on specifics, only what I notice with myself with inside workouts. My "drift" happens exponentially. I can probably do a 150-155 effort and stay relatively constant for an hour+ but if I try to hold a 165 (95% for me) I will eventually climb to my max and exhaustion unless I slow down to keep the 165. It all seems like internal heating and elevated core temp to me, I am doing more work and heat than my body can remove off. Maybe there is more to it.
Maybe look into how fast your HR drops after stopping or cooling down and research the relationship to fitness and load?

Heat is part of it, also as you sweat you lose fluid and your blood becomes more viscous, which is another way of saying harder to pump. So each beat does less and you need more of them to achieve the same work.

The other athlete is in better shape than you.

If hr is stressing you out like this, just don't use it. You have power. That's all you need. Train with that for a few weeks, then put the hrm back on and compare. You should either be pushing more power then, or push the same power with a lower, steadier heart rate.

But you really don't need heart rate at this point. Sounds like it's making things worse.

Having watched my HR for a couple decades, I think having both power and HR is a very good thing. One works with power zones to increase one's ability to hold power for longer periods and more power for shorter periods. Power doesn't report on your physiology, unless you can call no longer being able to turn the pedals a report. HR reports your physiologic zones. If you keep holding power as your HR rises and rises, pretty soon you can't hold the power. Rising HR is the advance notice of that. Pushing power while your HR has risen out of the zone in which you're trying to perform is counterproductive. You're not stressing what you're trying to stress. Note that is not true of the athlete you're trying to emulate.

I think 2 ea. 24" box fans would be your immediate next step, very inexpensive and effective. It's possible they won't make any difference, but you want to know that before trying anything else. I doubt you're dehydrating during these short workouts, but you could be overheating. Bare torso, right?

Next thing would be to forget about this time-crunched cyclist type of thing and do an endurance block. For the next couple of weeks, put in as much time in zone 2 as you can recover from, preferably 2 or so hour rides outside. You could simply be lacking in endurance. A good goal for decent performance would be ~400 hours/year. Ed Burke said that trying to do high end work without an adequate aerobic base was not productive. IME there's something to that. I start training for the next summer in October and don't start doing hard intervals until February.

Another useful thing would be to get a premium TrainingPeaks account and log all your workouts there. It takes some time to figure out how to interpret the Performance Manager Chart (PMC). I've found being able to chart my body's readiness to train has made a big difference. No canned workout schedule or online training plan is really usable without being able to interpret its effect on your body in real time.

Another remote possibility is the effect of spine problems on heart rate and blood pressure. I just had an ortho review for a full spinal exam and it's not good. My top two cervical vertebrae are in bad shape as are the lower lumbar -- mostly due to various accident injuries. Doc said that's one possible reason for my erratic HR and BP, particularly on a road bike due to the neck position -- although I often find my more upright hybrid to be more uncomfortable to my neck after a long ride.

So I'm set up for a few sessions with a chiropractor to see if it helps. I'm pretty skeptical about bonecrackers but it's what my insurance will cover, so I'll try it. I'll need to pay out of pocket for a massage ther@pist, which will probably do more good. ('scuse the odd spelling with the "@" symbol, but BF's word filters make hash of some perfectly normal words).

You can't hire a the****** from Pakistan on bike forums.

Edit: they fixed the Pakistan one!

This was a good post except for the above bolded part. Just IMO people are different with different goals, so prescribing a specific "base" amount of time isn't really helpful.

As it stands, it looks like I'll hit 320w for 20min this year and still never in my life have cracked more than 250hrs a year. I dare say that for 2020, I think I can get it to 340w for 20min on under 300 hrs per year.

Yes, sometimes you do need to go long. But a lot of endurance athlete hobbyists are frankly ******* when it comes to the tougher intervals and hide behind low intensity "volume". You know, the A-group rider who does 10k miles per year but couldn't do a 3x3min workout if you put a gun to their head.

Would I be faster still if I ramped my CTL up to some crazy value like 80? Probably. Am I pretty darn fast for spending half the time other people do? Yeah. Fast is relative, always faster folks out there. Maybe I'm a freak, I dunno.

Like you said, different criteria for different goals. I doubt many sprinters can run a marathon and visa versa. There is a lot of in-between. Is that really considered hiding behind something.
A while ago I could do 20-25 miles relative high intensity (1.3 hours at 90%+ max average HR, I don't have a PM) I've gradually morphed to mainly 45-100 miles rides at a lower intensity (3-8 hours at 80% max avg HR). I have no doubt if I did just my old 20-25 route today, my hill climbing speed would be less than it was before. What you are pointing out has happened in my case and I can also feel it on the hills. I am not an A group and almost exclusive solo so my riding performance is without competitive goals and is what it is so take with a grain of salt.

I think it's easy to fulfill your own prophecy. I continue to train and ride about as I did 20 years ago. I use the techniques, intervals, easy rides, moderate rides, hard rides, just like any competitive rider, I just don't compete formally. My results are just a little poorer every year. No big deal. I'm about the same amount slower than the same riders 10 years younger than I as I always was. I've lost ~10% off my VAM in the past 10 years. So has everyone else.

One thing that's helped is using smaller gears and pedaling faster. More aero helps, too.

If you're not trying to race or max out your fitness, what's the point of doing intervals? It's not particularly fun.

I sure wouldn't do intervals if I didn't need to. As mentioned, different goals.

People not racing do not need to do things that people racing may think they need to do.

You're better at things you do. You're not as good at things you don't.

That's true. Why invoke the hurt if it isn't really necessary.

Well, at this point I'm more poser than racer. Doing maybe 2 to 3 events a year, of which only maybe 1 is a USAC race versus gravel or duathlon isn't exactly a stellar calendar.

I'm just weird I guess. I really enjoy trying to get faster on the fitness side of things. It's fun for me to be able to blast around how I can. Even if there isn't a "W" or a "KOM" in it, it's neat to be able to chew up miles and hills and stuff at a good clip.

It didn't so much drive me nuts when I started out seeing people pass you or see your name way down on the Strava boards. I just didn't like going so slow.

I came from racing turbo Volkswagens in the 1/8th and 1/4, and ehhmmm other places. Gave that up to be more responsible. So, tweaking the power and going faster is just part of the hobby to me on the bike.

But.......no methanol injection for cycling.

Dope the f up bro

The consequences of a "doped" car engine could be confetti in the oil pan or a new viewing window in the side of your engine block. Sad and horrible things, but ultimately just costly in time and to the wallet.

Using the same analogy to tuning cars as bike training..........I think the consequences are much more dire when they deal with the human body. No thanks. I'd rather not put a hole in the "engine block" or have "confetti" in the "oil pan".

Increase maximal oxygen uptake capacity. Fitness is an end in itself.

Some people just enjoy the process of training and being in shape. Plus doing some intervals can break up a long ride and of course Strava KOMs lol.