This is the third time that I’ve trained to race an Ironman (aka “Full”) Triathlon. I will be participating in Ironman Louisville on October 11th. The previous two times I’ve done this race, it was held at the end of August. So due to this change, my training has been shifted by six weeks. I’m following the same plan that I did in 2013, which consists of mostly high-intensity interval training with a few long rides and runs mixed in along the way.
Since I don’t have a long ride or run every week like most people training for an Ironman do, it’s not as easy to gauge my fitness along the way. I track certain metrics, but nothing is as cut and dry as seeing how you feel during the weekly long bike rides and runs. I post all of my workouts on a website called Training Peaks. Everything from my Garmin 910XT watch is uploaded (time, distance, heart rate, power, etc.). Training Peaks uses all of this data and calculates something called Chronic Training Load (CTL). It’s a rolling, daily average of how much training load you are managing, measured by each workout’s Training Stress Score (TSS).
Your TSS is basically your workload for a particular training session and is calculated by the workout’s intensity and duration. The actually equation looks like this:
TSS = (sec x NP x IF)/(FTP x 3600) x 100
- sec = duration of the workout in seconds
- NP = normalized power
- IF = intensity factor (how intense the workout was based on % of your FTP)
- FTP = functional threshold power (highest power you can hold for one hour)
- 3600 = number of seconds in a hour
If you don’t have a power meter on your bike, or you are running or swimming, the TSS is calculated using perceived exertion or your heart rate.
So every day, my workouts are assigned a TSS by Training Peaks based on the data that is uploaded from my watch. My current CTL is then calculated based on not only that day’s workout, but also every workout that’s been logged in the past 42 days. This 42 day weighted average of my TSS turns out to paint a pretty accurate picture of my fitness level. It rises slowly as you get more fit, but also falls off quickly is you miss some workouts or take it easy for too long.
Knowing all of this, I thought it might be interesting (and fun) to look back at where my CTL (blue line on the charts) was at this point in my previous Ironman training years and compare it to now. We are currently 15 weeks from race day.
For Ironman Louisville 2011 (chart shown above):
Start CTL (36 weeks from race day)- 19.7
15 weeks from race day (5/15/11) CTL – 20.0
High CTL during training (4 weeks from race day) -58.8
Day before race CTL -28.0
For Ironman Louisville 2013 (chart shown above):
Start CTL (36 weeks from race day)- 34.0
15 weeks from race day (5/12/13) CTL – 49.3
High CTL during training (also 4 weeks from race day) – 78.5
Day before race CTL – 50.2
For Ironman Louisville 2015 (chart shown above):
Start CTL (36 weeks from race day)- 40.5
15 weeks from race day (5/12/13) CTL – 64.2
High CTL during training (also 4 weeks from race day) – ??
Day before race CTL – ??
So it’s good to see that my CTL is higher 15 weeks out than it has been in my previous two Ironman Training years, but if I look at my starting CTL for each of those years, I was at a much lower fitness level in the beginning of the 36 weeks. In 2011, my training was obviously not accomplishing much as my CTL didn’t move (20.0 versus 19.7) after 21 weeks! I was able to get it up 38.8 points in the 11 weeks after that, to a high point of 58.8. In 2013, I gained 15.3 points on my CTL in the first 21 weeks and then another 29.2 to a high of 78.5 four weeks from race day. This year I started off much higher. In the past, I’ve kind of let things go in the off-season, but this past winter I made it a point to train with a purpose and watch my nutrition during the months that I typically take it easy. My starting CTL this year was 40.5 and I’ve already gained 24.2 points. If my trend from the previous two Ironman seasons holds, I will enter this Ironman with a higher CTL than in the past.
The goal is to see a steady rise in CTL as you train for your “A” race (10% or 10-15 points per two weeks is ideal). I try not to focus too much on my CTL number as I don’t want to go for longer or harder workouts just to inflate my number and make my chart look better. I have my workouts set in a way that should lead to improved fitness as the summer rolls on, but seeing my CTL line head up like the Cliff Hangers game on The Price Is Right is a good boost to the confidence!
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