LTHR - inside vs outside?

Sufferfest has consistently placed my LTHR at 162bpm, including yesterday’s Half Monty test. I maxed out at 174bpm.

However, I’ve raced a few cross races in the last 2-3 months and my LTHR appears to be different. The cross races are 40-45mins long and during that period I average 170bpm, maxing at 176bpm. wants to put my LTHR at 168-170bpm but having used this for a few weeks I can’t hit the HR zones in workouts internally.

I know you that heat buildup limits your internal power, is there a similar limiting effect for LTHR internally? I’ve not seen internal and external LTHR called out differently in any training packages

When you max out in the HM test, how does it feel when you can’t go on? If your cadence is too low the limiting factor can move from cardio to muscular and you might find that you don’t get your HR up as high as it could, leading to an underestimate of your LTHR. If you have a power meter on your outdoor bike, how do the power zones match up with indoors?

Yes, the excitement of a race situation can raise your HR to levels not achievable in a training situation. Systm workouts should be ridden with power, ignore the HR unless the RPE also feels way off.

When we start to overheat our heart HR increase to increase blood supply to the skin and help cool us down. Once we have overheated our body effectively lowers the “rev limit” to prevent damage to the body, this can lead to reduction in max HR, power or both.

I rode The Way Out back in August on a hot humid day, during the 10 minute over-unders (overs only at 95% of FTP) my average HR was 5 beats higher than LTHR, by then end of that interval I was close to max HR I was completely cooked, for the rest of the workout my HR soared ( but was 5 beats less than my actual max) as soon as I put an power down in the intervals to the point I felt unwell and had to stop to cool down. My legs felt completely fine, in fact they felt great.

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Maxing out in Half Monty is like hitting a wall, everything stops suddenly. Cadence up to that point stays constant (90rpm ish), I don’t switch to grinding.

No power meter outdoors, always use power for indoors workouts.

I don’t feel overly hot when training or testing though, I’m in a garage that’s probably 10C with a big fan going straight at my torso.

Riding HM with a higher cadence might push you max HR up and enable you to get further up the ramp. I find my legs fall off if I don’t increase cadence once I’m past FTP on the ramp, I start off the ramp around 80rpm, I’m at 90rpm around FTP then increase up to 100 rpm until I can’t go anymore and grind the last bit out.

I’m the same no power meter outdoors, outdoor rides are done by HR and RPE.

A great way to test if your HM power numbers and HR are right is to ride Nine Hammers. If you make it through all the intervals without having to freewheel any of the recovery sections and feel like the last effort wasn’t max effort then your number are probably on the low side.

You have a similar cooling setup to me, If my sweat is not dripping on the floor in puddles the cooling is fine. That workout I mentioned from August I was wringing out a sweatband into a bucket and collected about half a pint plus a puddle on the floor from the rest of me.

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