Product Endorsement – WKO+ For Monitoring My Triathlon Training

Everyone who knows me well is aware that if you look up the word ‘geek’ in the dictionary my photo is next to it. I’ve always been keen on technology and this, coupled with my profession as an engineer make me a bit obsessive when it comes to data. And that’s being polite about it.  Fortunately, there are a number of tools out there which make it possible for me to monitor the effects of my training program which give me the ability to record lots of data, and tailor my training to my racing needs.

Besides having the necessary hardware to collect data – my Powertap cycling power meter and my Garmin 305 GPS watch – the most important element of my arsenal is my CyclingPeaks WKO+ software. This is an amazing program which serves not only as my training log, but as a tool for monitoring the effectiveness or otherwise of my cycling and running training.

One increases fitness by stressing and de-stressing your body. Over time, your body adapts and your fitness improves.  Your fitness level therefore depends on two elements: (i) training intensity; and, (ii) training volume.

The intensity of a workout is measured as how hard each training session is, relative to your ‘threshold’ abilities.  Threshold is the point where the blood lactate accumulates and your performance drops off. For cycling this is my  threshold power (currently 230 watts); for running threshold pace (currently 7 minutes/mile).

Research showed that the blood lactate level was a function of cycling power to the 4th exponent.  The ‘Intensity Factor’ (IF) when cycling is therefore calculated as:

IF = (Power^4)/Threshold Power

I’ve not confirmed how it is calculated for running yet, but it is from the average pace during the workout. In workouts, the IF is as shown below  If you regularly have workouts over 1.0 it suggests that your threshold power/pace has changed.

  • < 0.75 – Recovery
  • 0.75 – 0.85 – Endurance training
  • 0.85 – 0.95 – Tempo/Interval work
  • 0.95 – 1.05 – Hard interval work
  • > 1.05 – Very hard short work

The total stress score (TSS) for the workout is calculated from the intensity and duration:

TSS = IF^2 x Duration x 100

This means that more intense workouts, for shorter periods of time, are equivalent to much less strenuous workouts for longer periods. Not rocket science.

Enough of the theory. It isn’t necessary with WKO+. My power meter records the wattage profile that I generate when cycling, or my Garmin run is uploaded (unless on a treadmill in which case I have to manually enter the data). From this all the work is done.

The chart below shows the training stress score (TSS) for the last four weeks of training. It’s easy to see when I was travelling by the large gap last week.


Studies have shown that you can essentially divide your TSS into the following ranges:

  • < 100 – Low Stress – Easy to recover by the following day
  • 100 – 200 – Medium Stress – Some residual fatigue next day
  • 200 – 300 – High Stress – Residual fatigue even after 2 days
  • > 300 – Epic – Residual fatigue lasting several days

Since this is currently the off season, I am not having high stress days – and with my winter running on a treadmill the running stress is being underestimated since it cannot handle interval runs very well.

How much TSS can one handle? For serious athletes 100 – 150 TSS/day seems to be the “optimal” training load. Duffers like me are below 100. Few if any athletes, even professionals, can handle over 150 TSS/day for long periods.

Measuring TSS allows for one to monitor one’s overall fitness, and even forecast how one will perform in the future.  Looking at the last six weeks, one can calculate the ‘Chronic Training Load’ (CTL) which essentially is a measure of fitness – how much training I have stored up over the long-term. Or as some as described it, how long one can go fast. This is the blue line below which shows over the last month a 10% increase in my CTL. This chart shows that I’m currently plateaued with my training and need to work a bit harder – or longer. But then it is the off season 🙂


The second measure we have is the ‘Acute Training Load’ (ATL) which is based on the last 7 days of efforts and is the pink line in the chart above. This is how much I have been training recently.

The ‘Training Stress Balance’ is the difference between the two (TSB = CTL – ATL) and is the golden bars.  The TSB is a measure of how much training has been going on, or my ‘freshness’.  It is important that the TSB is not always negative, as that indicates not enough rest/recovery time. In the above chart it is negative which shows that I have been training hard relative to my current fitness level. When you are getting ready for a race you do not want this to be negative since you will not do well in the race – hence the need to taper. With a TSB of -10, you don’t feel fresh; above +10 you do.

It is interesting to look at the effects of travel on fitness. The chart below shows the last two months. The drop in December happened when I had to travel to Toronto for a week due to my mother’s illness, and the resulting interruption to my training then and afterwards.  Chronic jetlag (I’m writing this with 3 h sleep) doesn’t help either 🙂


So that is how I monitor my performance. Does it help? Hopefully. But even if it doesn’t I’ve lots of interesting data to play with! There is also a lot of truth in Alex Simmon’s statement: “The [performance management] chart is a one picture summary of the truth, as useful and brutal as honesty can be.”

Time to get on my bike and do some interval training!


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