Live/Train at Altitude Race at Low Altitude

John Schneider

Question, I believe the last time I asked this question I got a response from WSM - Al Truscott.

I live in Denver, 5,000 feet elevation.

If my bike race watts is 180, when I go to race at Low Altitude I need to increase my watts 10% to account for thicker air etc, is that correct, so 180, 10% is 18, racing at 198 watts?

Assuming the above is true, does this apply to running with Stryd power as well or is running a separate animal altogether? Weight is 165'ish if that makes a difference.

One more question, bike tire pressure if I pump up to 90 lbs at altitude, do I need to go a little higher at lower altitudes?

Al Truscott

1. I use the same tire pressure whether I am @ 0 or 12,000' or anywhere in between. I think the key thing is the pressure against the road relative to bike + rider weight, not pressure of tire against the ambient air, to achieve best balance between preventing pinch flats and gaining the best contact patch.
2. While I have run with a Stryd at altitude, I haven't actually reviewed the issue specific to altitude. But I do know that, at least on flat ground, my Stryd power is directly proportional to my pace. And I do know that threshold pace is reduced @ altitude similar to bike FTP. So it would make sense to use a higher # for Stryd power when going lower in altitude.
3. 3. If I led you to believe that 10% was a good discount for 5,000' altitude compared to 0', I may have somehow led you astray. For myself, riding at an average of 8-9,000' around Aspen, when I am fit, I notice about a 5-7% reduction in my FTP. EG, I will drop my FTP from 213>>200 when calculating TSS compared to sea level. 5,000' in a well trained athlete compared to sea level would be about a 3-5% difference. So, my suggestion would be, raise your FTP by just a small amount. If it's 250 in Denver, it should be no more than 260 @ sea level, IMO. But make sure you triangulate with two other metrics while racing, to be sure you are not over-cooking the bike: HR & RPE.

John Schneider

Thanks so much for the input Al, I was not remembering you last advice correctly, what a shocker :) so thanks for the refresher!!

Robert Sabo

I would like to add a question of clarification. Does the heart rate targets stay the same? and if you altered pace/power by the heat adjustment does the heart rate targets also stay the same?

Thanks Al and John for this question/answer.

Rich Stanbaugh

A quick thought on the “why” of tire inflation pressure: Al is spot on, inflate your tires to the same pressure.

Air pressure is a relative measurement. For example, sea level air pressure is equal to 29.92” of mercury... in other word the air pressed hard enough to displace 29.92” of mercury. At Al’s Aspen house, that pressure will be about 22.2” since there is less air pressing down on the mercury

When we measure fire pressure, that is guage pressure. Guage pressure is a differential measurement of pressure inside a tire be air pressure outside a tire. So, inflating to 90 psi at 8,000’ is 90 psi relative to the outside air pressure (22.2”) and inflating is o 90 psi at sea level is 90 psi relative to the outside air pressure at sea level (29.9”).

If you inflate at sea level, level the valve closed and the. Put the tire on an airplane cargo that is not pressure controlled, then go to 30.000’, the tube may pop because the amount of air needed for 90 psi at sea level is dramatically more that the amount needed at 30,000’, so the gauge pressure would be much bigger than 90 psi.

Al Truscott

https://endurancenation.vanillacommunities.com/discussion/comment/277049#Comment_277049

@Robert Sabo For me, when cycling the long (13 mile) climb from about 8-12000', I notice, if my heart rate stays the same, my power diminishes while I ascend.