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MEASURING A RIDER’S POWER OUTPUT
Functional Threshold Power
Functional Threshold Power is defined as the highest power a rider can sustain for one hour at a steady
rate. A full Functional Threshold test will take 60 minutes. However, 95% of a 20-minute average test
correlates closely with a 60-minute test. The results allow riders to calculate and train in various power
zones. In addition, shorter power tests may be attempted for a more manageable application in classes.
For example, Keiser’s Personal Power Test is a shorter-duration test and can be completed as a 3-, 5-, 10-
or 20-minute test. When a shorter test is being used, a correction factor must be applied. A correction
factor takes into consideration the amount of systemic error that might occur by not doing the full
60-minute FTP test (Allen & Coggan). Thus, average Watts from the shorter test are multiplied by a
correction factor between 5% and 20% to determine a final FTP personal score. The correction factor
use (i.e., 5%–20%) depends on the duration of the short test chosen.
Here are the suggested Keiser Correction Factors:
3-Minute Test:
20% Correction Factor
5-Minute Test:
15% Correction Factor
10-Minute Test:
10% Correction Factor
20-Minute Test:
5% Correction Factor
Peak Power
Peak Power is the highest power output a rider can achieve. Typically, this is measured by attempting
to reach maximum power during a 15-second interval.
Average Power
Short-duration power testing can be completed in one- or five-minute measurements. These results can
also be used as baseline and repeatable training goals.
HOW TO INSTRUCT A (FUNCTIONAL THRESHOLD) POWER TEST
The goal of a (Functional Threshold) power test is to encourage and challenge riders to ride at their
highest steady state (defined as the highest amount of power a rider can sustain at lactate threshold).
To effectively instruct a power test, make sure to:
•
Adequately warm up the riders for a minimum of 10 minutes prior to the test starting
•
Reset the computer to zero or start a new interval
•
Choose drills or instructing strategies that motivate a rider to stay at lactate threshold
•
Use words to describe the physiological response at lactate threshold. For example, the rider should
visualize that he or she is riding up a steep hill against a heavy headwind.
CONCLUSION OF THE FTP TEST
•
Remind riders at the end of the test to remember their calculated average Watts
•
The test results go into a formula to determine an individual rider’s training zones based on Watts.
See test examples and results on the following pages.
PHYSIOLOGY
