Wednesday, September 02, 2009

More on Friel's Decoupling

Friel has a simple summary of his decoupling thesis at:

I'll summarize it even more: He says that for serious cyclists, aerobic fitness is best developed by riding at 65% to 75% of FTP. That puts me at about 200 watts, or upper portion of L2. He says if I'm training for longer road races, my decoupling should be less than 5% for 2 to 4 hours.

Calculate it by taking NP for the 1st half of the workout and dividing by average HR for 1st half of workout to get (NP/HRave) = A. Do the same for the 2nd half of the workout to get B.

Then check the percent increase by taking [(B-A)/A] x 100. If this percent decoupling is greater than 5%, aerobic fitness is not fully developed (unless heat or improper hydration have played a role).

I'm going to try a longer, slightly lower power test today (maybe 200w for an hour) to see how the decoupling looks.

1 Comment:

Walker said...

Great find. I looked back at several of my endurance rides and found that the Pw:HR number is heavily affected by sections where you coast to a stop b/c your HR is still higher than resting. This shoots the % higher. Of course these small sections seem to average out over time, but it means that you need to have a longer time interval to reduce their influence.

In his examples he has a 5hr ride, a TT, and a hill climb. The last 2 are steady efforts, and the first would definitely average out any short coasts.

I'm guessing the point is that aerobic conditioning can be determined with this number as long as you keep the test effort as steady as possible for a decent length ride (1.5-2hrs?) depending on your goal event.