impact of altitude on heart rate/ HR zones

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impact of altitude on heart rate/ HR zones

Postby tliebl » Wed Jul 28, 2010 8:21 pm

To the sports physiologists at Hammer,

Have a burning question that needs to be explained/answered regarding heart rate monitoring and response and the changes to these that occur at altitude. Some baseline information; am a 51 year old male with a max HR of 180 and an LT heart rate of 174, living in KS. I can ride for hours on fast paced group rides at HR in upper 150’s to upper 160’s and still get into the red zone for periods with a pretty quick recovery. Do a fair amount of interval work using a trainer with specific interval goals (power improvement, etc). My main focus of racing is endurance mountain bike racing (100 milers, 200 milers and 6 or 12 hour events) and most of these are done in the Colorado area at altitude (Breckenridge 100, Leadville 100, etc)

Here is my question. Do the heart rate “zones” that I have established in Ks make any sense at altitude? In doing races in the Ks are, I try to keep my heart rate in the zone 3 and 4 for most of the time and avoid to much red zone rates if possible (again, these are very long races). This works pretty well. BUT, I just raced in the Breckenridge 100 (and remember the same thing happening in last years Leadville 100) and in the final ½ of the race, it seemed like my effort was high but when I would look at my HR, it was often times in the upper 130’s to mid 140’s. I honestly don’t know if I could have pushed my legs any harder in an attempt to get near my LT as it already seemed like my perceived effort was high. Does one’s power output drop when going from sea level to 12,000 feet and does this show up as a change in the HR for any given perceived effort? I don’t have “free” time so I arrive in Colorado to “soft spin” on Friday and then race on Saturday. If you could give me some insight on the effects of altitude on perceived effort and HR it would help greatly. I felt like my body was hitting the wall at a climb at 80 miles and my HR said I was doing a “wimpy” effort.


Tom Liebl
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Re: impact of altitude on heart rate/ HR zones

Postby steve-born » Thu Jul 29, 2010 1:41 pm

Hello Tom -

I posed this question to Dr. Bill who responded: "Heart rate (HR) at altitude is less by 5% for each 5000 ft above where you live and train. Most of us living below 2000 ft have a 20.9-21% oxygen level where we live, but at some of the peaks near Leadville the O2 saturation level can be 25% less. Without normal oxygen saturation the heart rate max level may simply not be reached. I typically tell people to stay within themselves when doing a race at altitude, simply because if they try to reach the Max heart rate (MHR) at sea level or where they train and live, it cannot be done. At altitude HR may not be appropriate dictate for pace."

I hope this helps answer your question.

Sincerely -

Steve Born
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Re: impact of altitude on heart rate/ HR zones

Postby tliebl » Thu Jul 29, 2010 8:42 pm

Thanks so much for the information (and send thanks to Dr. Bill). It makes good sense and now my "ego" is not so tarnished.
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