I have a computrainer and I did something for the first time the other day that really made me think. I was in the ergo mode so the load remained constant. I was riding for about an hour in the middle of z2. HR had remained constant for about 45 mins. My butt was hurting so I sat up, holding onto the bullhorns and I could watch my HR go from 142 to 132 in about a minute or minute and a half (power and cadance remained the same). I didn’t think I had a very aggressive postion, but 10bpm seems like a ton to me. Does this sound like I’m losing a lot of power in my aero position to anyone else, and how much power loss (or HR increase) is acceptable in the aero position? No, I’ve never been professionally fit, and I know that is probably a good place to start, but I feel very comfortable on my aero bars and, until now, thought it was also fairly powerful position (relatively speaking here.) Thanks for the input!
I have a computrainer and I did something for the first time the other day that really made me think. I was in the ergo mode so the load remained constant. I was riding for about an hour in the middle of z2. HR had remained constant for about 45 mins. My butt was hurting so I sat up, holding onto the bullhorns and I could watch my HR go from 142 to 132 in about a minute or minute and a half (power and cadance remained the same). I didn’t think I had a very aggressive postion, but 10bpm seems like a ton to me. Does this sound like I’m losing a lot of power in my aero position to anyone else, and how much power loss (or HR increase) is acceptable in the aero position? No, I’ve never been professionally fit, and I know that is probably a good place to start, but I feel very comfortable on my aero bars and, until now, thought it was also fairly powerful position (relatively speaking here.) Thanks for the input!
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The fact that your heart rate was higher when in the aero position doesn’t necessarily mean that it was costing you any power at all.
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In answer to your overall question, the answer is “only as much as is outweighed by the reduction in aerodynamic drag”.
I have a computrainer and I did something for the first time the other day that really made me think. I was in the ergo mode so the load remained constant. I was riding for about an hour in the middle of z2. HR had remained constant for about 45 mins. My butt was hurting so I sat up, holding onto the bullhorns and I could watch my HR go from 142 to 132 in about a minute or minute and a half (power and cadance remained the same). I didn’t think I had a very aggressive postion, but 10bpm seems like a ton to me. Does this sound like I’m losing a lot of power in my aero position to anyone else, and how much power loss (or HR increase) is acceptable in the aero position? No, I’ve never been professionally fit, and I know that is probably a good place to start, but I feel very comfortable on my aero bars and, until now, thought it was also fairly powerful position (relatively speaking here.) Thanks for the input!
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The fact that your heart rate was higher when in the aero position doesn’t necessarily mean that it was costing you any power at all.
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In answer to your overall question, the answer is “only as much as is outweighed by the reduction in aerodynamic drag”.
Good point, I guess my real question then is: without going to the wind tunnel, does this sound like my HR is too high for my output? I know this is an individual question and no way to know for sure without going to the tunnel, but I’m looking for opinions. Has anyone done something similar to this? Anyone think my position is way off, in need of a little tweaking, or ok the way it is? 10 bpm sounds like a lot to me, but I have nothing to compare it to.
Stop focusing on HR and just concentrate on power. HR can’t be used to accurately measure effort, power can.
but doesn’t it seem reasonable to say that I’ll able to maintain the same power longer if my HR is 132 rather than 142 at the same wattage? HR, although not perfect, seems to be a much better measure of effort, or input, and power is a measure of my output.
Good point, I guess my real question then is: without going to the wind tunnel, does this sound like my HR is too high for my output? … 10 bpm sounds like a lot to me, but I have nothing to compare it to.
+10bpm is not uncommon when first trying an aggressive new position. Two things – first, it gets better with practice. Second, it might or might not matter. Fatigue happens in your legs, not your heart. If your heart is beating a little faster because of, say, some constriction in the femoral area or diaphram, you can probably still cycle OK at the sub-threshold power levels involved in long-course racing. Restriction might limit your high-end power in a TT or sprint race. And, as Andy said, it might not be affecting your power at all.
The best approach is to try it and see if you can hit the same race times in some non-A races. Even better is to have a powermeter and go out and test on a flat road.
HR, although not perfect, seems to be a much better measure of effort, or input, and power is a measure of my output.
That might seem to be true, but it isn’t, at least not in this context.
keep it simple - it may be that a change in position, after 45 min in one position, let you recruit muscles differently - which were not as fatigued and thus…lower HR.
A very good point that I had not thought of. Sounds like my findings are not that terrible after all???
keep it simple - it may be that a change in position, after 45 min in one position, let you recruit muscles differently - which were not as fatigued and thus…lower HR
That’s simple, but probably not what’s going on here 
These changes in HR with position have more to do with blood circulation and gravity.
i would also wonder what happened to your cadence when you sat up. because it’s in the ergometer mode your power didn’t (theoretically) suffer at all, because the CT keeps your power output constant in that mode. but if you reduced your cadence (which often happens when you sit up) you’re increasing your torque at the expense of your cadence. this probably does require less oxygen consumption, but at the expense of recruiting type II fibers, which are more glycolytic.
that sort of fiber recruitment versus oxygen consumption trade-off is harder to justify at higher effort levels, but at low effort levels it works nicely, and that’s why RAAM riders can ride at 65rpm but crit riders cannot. the point is, if i was to take a guess i’d be willing to bet you were not riding very hard during your hour on the CT, and it was a cadence change that caused your HR to decrease, not your position change.
i’m glad andy is monitoring this thread, i’d be interested in what he has to say about this.
one other thing about this, i have several computrainers and i don’t think they’re all equal in terms of their abilities to normalize power at different cadences. CT says yes, all the resistance units properly pit torque against RPM to achieve a constant resistance, but i know that i have units that do not seem to work as advertised. but again, the assumption is that your cadence dropped when you sat up.
okay…prove it ;-).
I did consider the difference in rpm so I tried to keep that constant. I was averaging 90 rpm while in the aero and tried to keep it close while sitting up (88-90 rpm). Yes, it was a relatively easy pace (I was aiming for the middle of my z2).