Wondering if anyone has come across normal distributions of aerobic efficiency vs power output.
I’m thinking of a graph with % of max aerobic power on the horizontal and w/hr(5 minute) on the vertical.
The purpose would be to better understand the typical aerobic performance trend of athletes within power zones.
I find myself performing poorer efficiency for endurance workouts than for sweet spot, and wondered if my results are typical or telling that I need to spend more time developing my base fitness respective to threshold power.
Hi,
I guess it’s normal. If you output very little power your heart doesn’t stop so the lower the power the worst power/hr ratio and on the other side when your hr is close to max your efficiency rises with power (as long as you can sustain it)
Anyway my numbers:
2h SS, IF 0.87, Eff:2.48
1.5h E, IF 0.67, Eff:2.19
The other factor is the length of the workout. The efficiency will drop because of the cardiac drift
2 Likes
Ya, I was thinking the same, the limit on the bottom is 0 watts over your resting, and at your MAP, it’s basically your maximum heart rate.
I wonder what that line in the middle is supposed to look like, I think the efficiency improves as you approach the MAP.
I’m about 1.45 in endurance 1hr, and 1.6-1.7 for sweetspot.
Nice ratios by the way!
Indeed a very interesting metric to monitor, although I am not sure it is very useful for comparison between athletes. As me tioned above, your efficiency will rise in higher zones. Maybe the ratios between zones’ efficiency between athletes can be compared?
I’d like to add the following: HR is very individual, so when you combine it with the power curve, you confound two variables at the same time. Also, HR varies with age, so you would need to account for that. Still, you can use your values to see if you are improving in certain zones.
PS. My values for comparison:
- VO2 max ~1.95
- Threshold ~1.85
- SS ~1.72
1 Like
They are very individual and should not be compared. My max HR during last two years was 157. Absolute max was 164 more then 10 years ago. That explains the ratios 
As I currently measure power only on a trainer my endurance rides are shorter, usually at least partly underfueled (early morning = fasted) and with less cooling (no fan = less noise). All of this has an impact on a heartrate so if you want to measure progress with this metric all the other factors should be as similar as possible. Ideally the same workout with very similar conditions.
1 Like
What is useful to know is the LT1 point (first lactate threshold, or aerobic threshold - basically the point at which lactate starts to ramp up and cannot be adequately cleared, also the point that you start to switch to a reliance on glycogen rather than fat). This is a good sign of aerobic fitness.
The test that I do is to set a HR cap at the top of Z2 HR (based on LTHR%). after a warm up, do 1 hour at this heart rate, modulating power as necessary.
This gives you two things that indicate aerobic fitness (although you have to account for the standard variables that impact HR):
- LT1 Power
- Aerobic decoupling
If less that 2% aerobic decoupling, you can be pretty confident that it is LT1 power. If the power has to drop significantly through the effort due to aerobic decoupling, LT1 is probably lower and there is a requirement to build more base / aerobic endurance.
3 Likes