Lower HR @ altitude?

Has anyone experienced a lower heart rate and lower performance at altitude?

My wife seems to struggle at altitude but after reviewing her files I’m grasping for a reason that her HR would be lower at 9000 feet than when she races at 5500 or 7500 feet? This is not just one race, it is multiple races we’ve seen this happen.

Has anyone seen a study or heard of a reason that this might be the case? My expectation would be to see an elevated HR for the power output and that is what I see in the literature. I am at a loss as to why her HR would be lower unless there is some sort of mental reason that the lower o2 saturation basically scares her brain into backing off more than she needs to.

Any ideas?

What is her power at altitude? It is likely less also, hence the lower HR.

Note: resting HR at altitude is typically higher, but max HR lower.

Yes lower power. When I race at altitude my HR is in the LT zone for almost the whole race except for extended descents where I have time to get it lower. For her she is spending most of the race in her tempo HR. I guess it’s possible I’m the weird one but would like to hear other people’s experiences. Thanks Dave.

How does she feel at altitude? Does she get some sort of altitude sickness? Maybe she just doesn’t feel well, and can’t push as hard.

Yep that is it. Just feels terrible and can’t push but I’m trying to find out why it seems to effect her more than other people.

Altitude sickness is a thing, but assuming your wife is acclimated, male and female physiologies react differently to altitude (study). After acclimation, male physiology uses more carbs (so high-intensity fuel) and female physiology uses fewer carbs and more fat (low-intensity fuel). What kind of effort is your wife trying to put out?

(I read Roar this year, and it’s got a chapter on extreme conditions and how to deal with them. Recommend to anybody with any stake in training a female physiology.)

Reduced oxygen in the air inhibits oxidation in an athlete’s body. Lower oxygen consumption leads to lower CO2 concentration in the blood which keeps heart rate low.

Hmm. I should have said this in the first post. We live at 6,000 feet in Colorado and race CX and MTB so she is acclimated to that altitude.