New Features on


Here’s a sneak peek at three cool new features that are coming to with this week’s site update: Elevation Correction, Efficiency Factor, and Decoupling. Although these features are new for athletes (Premium only) and for all coaches who use, they are already available in WKO+ for those who prefer to analyze their data on their PC desktop offline.

Elevation Correction Explained, by Gear Fisher  


A great new feature with this week’s site update is the ability to apply an elevation correction to your GPS workouts. As good as GPS devices are for tracking speed and distance, they suffer in the ability to record accurate elevation data.  This is just an inherent limitation to GPS technology. Without the ability to read signals from satellites above and below your position on Earth, the elevation reading is susceptible to significant error due to the nature of the math being used to calculate your coordinates.  However, we’ve come up with a simple solution to this problem.  

We’ve combined several surveyed datasets into our own worldwide, proprietary database whereby we can take your horizontal position and match that up with the elevation data from our database.  In almost every case, this results in more accurate elevation calculations, especially for hill slopes and calculations of absolute elevation gained/lost.

To access this new, premium-only feature, open up any workout where you’ve used a GPS device and open the “Map & Graph”. At the top of the screen is a new “Elevation Correction” button.

Once launched, you can see a preview of the new elevation profile compared to the one recorded by your device.  Because in some circumstances the corrected elevation data may not be as accurate, you can choose to apply the corrected data or ignore it.  

Applying the correction causes your screen to refresh with the new data.  This works for any premium account user, on any file recorded with a GPS device.  If for any reason you want to get your original data back, just download the original file from the QuickView as shown below, and re-upload the file back to the workout.  

Elevation correction is available to all premium subscribers. If you are a WKO+ user and you download from into WKO+, you will be getting the corrected data if the elevation correction has been applied.  Finally, if you are using any of our mobile apps like Run Tracker Pro or Cycle Tracker Pro, we have already been adding the corrected elevation data automatically to any workout uploaded to the site.

Efficiency Factor and Decoupling Explained, by Joe Friel

©Joe Friel 2011

Heart rate-based training has been around about 30 years. Power-based training is somewhat newer, having arrived on the scene some 20 years ago. Speed-distance devices that measure pace have been around about 10 years. Heart rate is a good way of measuring how the workout felt; it’s a proxy for effort. We can think of this as “input.” Power and pace tell us what was accomplished in the workout or race. This is “output.” When input and output are compared, we have an excellent way of measuring changes in fitness. “Efficiency Factor” and “Decoupling” use this relationship to tell us how fitness is progressing. With this new site update, Premium users will now see EF and Decoupling metrics for each workout.

Efficiency Factor (EF)
We have known for decades that if heart rate during an all-aerobic (below lactate/anaerobic threshold) workout rises while the intensity (power or pace) stays the same, then the athlete is not operating efficiently and his or her aerobic endurance is questionable. The same is true if heart rate stays the same and power decreases or the pace slows.

To determine EF, our software divides normalized power or normalized graded pace by average heart rate for the workout (or selected workout segment such as an interval). By comparing the resulting ratios for similar workouts over several weeks, you can measure improvements in aerobic efficiency. To be reliable, the workouts need to be quite similar by making sure all of the elements are alike. This includes level of pre-workout fatigue, equipment, course, weather conditions, altitude, pre-workout nutrition (especially stimulants such as caffeine), warm-up and perhaps even time of day. The more similar all of these are from one session to the next, the more valuable the information is. If you are making good aerobic progress, then your EF will rise over the course of a few weeks.

This is a way of measuring output-input relationship changes that take place during a workout or race as a way of determining aerobic fitness. For this metric to provide useful information the workout or segment must have been fully aerobic (below the lactate/anaerobic threshold) and steady (low Variability Index).

What TrainingPeaks does here is compare the Efficiency Factors for the two halves of the workout or selected workout segment (such as an interval). The difference between the EF for the first half and the EF for the second is divided by EF for the first half. This produces a percentage of increase or decrease in the second-half EF.

I like to see athletes achieve a decoupling of 5% or less (negative numbers are, of course, less than a positive 5% and may reflect outside variables such as warm-up and weather but are assumed to be good results). As with EF, there are many variables that affect decoupling. These must be controlled.

Generally speaking, if an athlete’s decoupling is consistently 5% or less for steady-state aerobic workouts, then his or her aerobic endurance is sound. For example, if you quit training for a while your decoupling will reflect your loss of fitness. This will be obvious as an increase in fatigue late in the workout causing either heart rate to rise or power or pace to worsen—or both. In either case, decoupling will rise above previous values for the same workout and may result in decoupling of greater 5%, indicating a need for more aerobic training.

Premium users will see the metrics EF and Pa:HR or Pw:HR added to your “Map & Graph” view of a workout.  Pa:HR measures your decoupling rate based upon your normalized graded pace, while Pw:HR measures your decoupling rate based upon your normalized power.  EF and Pw:HR are shown in the screen shot below.

More features to come!

We hope you enjoy the new features and that they demonstrate once again that by uploading to, you can actually improve the data that comes from your device and make it even more effective for your training purposes. Look for more killer features like these in the future as we’re always working to improve our systems to help you reach your training and racing goals.