Heart rate on trainer

I always had trouble on my old dumb turbo to get my heart rate up to the higher end of Z4 / low Z5 during interval sessions or hard efforts. Thought this was maybe down to the trainer not being able to generate enough resistance, but the problem persists with the new smart trainer (Elite Direto).

My legs will blow up well before I get to 160bpm. I’ve an FTP of 235W, aged 45, 71kg. Max HR approx 175bpm.

Out on the road when pushing hard on climbs, my HR will be in excess of 160bpm, and I am able to maintain that for a short period, although have no power meter on the road bike to compare against.

When out on a run, I can hold a steady 150bpm for +45 mins at 7:00min/mile pace. That HR on the trainer would last about 10 mins max.

Have tried warming up better before harder efforts on the trainer and improving cooling with a fan and a damp cloth on back of neck, same results.

Is this just something I have to live with on the trainer?

Can’t really help but my numbers other than HR (age 41, ftp 250-270, weight 68kg) are not dissimilar to yours and yet I’ve hit 190 bpm on my trainer and regularly top out from HR not power (hard races that take me into 175-180 are common and unsustainable for long). Is there any chance you’re overtrained, because I understand the heart does struggle to get high when fatigued.

I do find higher HRs more comfortable outside, 165 indoors starts to hurt, outdoors I’ve seen it when I thought I was cruising in Z2, which I put down to heat and lack of distractions. But as to why you can’t get there at all I don’t know.

Have you done the FTP ramp test, that’s where I top out. I go 10 bpm higher at fail than I’ll typically see in any workout or race.

Have ruled out fatigue (for the moment anyway) as I thought that before, took some time off and it was the same on return. I follow a training plan with rest day and mostly endurance based training (for IM) with only a couple of big efforts per week. To be honest, I’ve never felt fitter on the bike.

I’ve done the ramp test on new trainer, maxed at 155bpm.

I think in general my HR is low, have only even seen 180bpm once during a 5k race, and my resting HR is average of 45bpm.

155 at fail on the ramp test must be physiological, I sit happily at 155 in low tempo power.

My average resting is also about 45 on a rest day. I’ll leave it to someone who understand the physiology better, but it can’t be your trainer setup I don’t think

Thanks, maybe I’ll put a bit of tape over that part of the screen!!

I am 59, RHR ~56, max HR 168…I have ridden outdoors in summer and indoors in the winter and it is always much harder to get the HR up indoors. My theories:
Temp differences - body works much harder in the heat
Outdoors…unless racing (I do not) I always get to stop and rest (lights/signs, coasting, etc.). Indoors not so much. So outdoors it is easier to push hard for short periods and ease up (soft pedal). For me it is very hard to soft pedal indoors. In Watopia there are many more riders than IRL (vast majority of rides) so always a wheel to jump on and keep pushing.
So my point is that IME riding indoors it takes a while for the legs to get used the constant use/abuse and crap out prior to the heart.

And I may not know what the heck I am talking about.

Of course YMMV and all people are different. I remember at a local GYM they provided a service to determine your zones with the breathing machine. They had one young lady hooked up and she never reached AT…hauling ass at 15 mph on the treadmill and HR of 215 or something…she had some good genes.

Couple things. The Zwift platform offers a very different riding experience than outdoors. Very constant power and HR reflects that. Much less variation than outside due in part to lack of wind, lights, corners, drafting, etc. Now, as a test, you might wish to give a different virtual platform like RGT a test drive. It’s free to ride a few roads and free to join a group ride. It is a very different riding experience and more like real life. Braking for corners, drafting, constantly accelerating and holding a wheel. Just something else to compare. My HR is still different in RGT but closer to outdoors than Zwift.

You have better cardio than anareoby on bike

When i start zwfit this winter i’m off since 3 months, naturally i have good resistance of anareoby effort (10 years of good level track and field sprint)

I hit my max HR really easly at start => 202 just need VO2 and AC workout.

Now after 1 months of traning with much Z2 workout it become really hard to go over 190 and i must give all for go 195+

For exemple on TT (45min) i have 182 avg HR, max 202 (final sprint after short recovery) i stay 15min 190 to 200, at end i’m totally exhausted.

Reading around various training websites, it’s well recognised that HR is lower indoors, It’s not known precisely why. British Cycling recommend having two FTHRs, one for indoors and one for out.

Normally my HR indoors is lower than expected for the power zone I’m in. But on a Zwift long FTP test (20 mins) I maintained my outdoor FTHR for a full 20 mins. Buggered if I know what’s going on.

That must vary by person then because I’ve never gone higher outdoors, it just hurts less except v top

I’ve got a 7 min climb near me and my hard effort (but not complete exhaustion) PR on that came with a 174 HR. That’s basically exactly what I’d expect on a similar effort interval in Zwift

I do think heat is a contributing factor, I’m in the house at the minute which is generally warm but I do have a large floor fan, hopefully have a bike-cave ready in about a month when I can have a lower temperature.

Just a follow-up on this, took an opportunity to get the temperature lower where I currently have my trainer set-up (my wife did not thank me for opening the doors and sucking in the sub-zero air from outdoors using the floor fan), but it did make a difference and during a race I was able to hold a higher w/kg for longer than normal so it definitely is a contributing factor.