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5k + Duathlon + Triathlon : Tracking your improvement (or not) with TRIMP CTL TSB ATL

18 December 2011
the5krunner

I think I’m a contender for the award for the post with the most previously unheard of acronyms in the title.

These acronyms being TRIMP : CTL : TSB : ATL

Essentially they help you broadly understand  the effect of your training on your body. Answering questions like: “Am I really improving?”; “Am I too tired to train?”; “How good is my taper?”; that sort of thing.

They work over any endurance sport. You can use them with power meter info from bikes (but let’s ignore that) and I’m going to focus on their most useful application with your heart rate data.

You are still going to do your pace based training and probably all the same old training you have been doing BUT you’ll be getting a better insight into how it’s all fitting together. So maybe you can tweak it a bit.

It borders on rocket science but you don’t have to understand the formulae. I’m reasonably mathematical but I can’t be bothered to even try to understand how they work. I haven’t got the time. I’m just going to use and interpret the pretty graphs they produce!

If you use SPROTTRACKS v3 then you will get the info with the TRAINING LOAD plugin by mechgt. I would imagine you will find it in TRAINING PEAKS and all other good software packages for athletes. SPORTTRACKS is free tho!

I’m learning a bit myself so I will revise this post if my understanding changes. But I’m going to keep it simple anyway to start off with.

TRIMP: If points make prizes then how hard you try and how long you try for in your exercises MAKES TRIMPs. TRIMPs are the points for your heart working in all the various zones with more points for when it gets to heady heights. So my 5k PB TRIMP is about 80 but tonight’s turbo session was 140. Doesn’t really matter. I could do a 5k tomorrow and get 82 and not get a PB it’s not (that) important in itself. Obviously my 5k PB was in a high HR zone for a little while whereas tonight’s turbo session had it between 162 and 173 for over 40 minutes. So tonight I didn’t work so hard but I worked for longer.

ATL looks at YOUR TRIMPS over a short period. So it measures how knackered you are. When you are really knackered you just ease off the training a little.

CTL looks at your TRIMPS over a longer period and says that’s how fit you are (compared to YOU previously). So ideally CTL will trend upwards.

TSB looks at the balance between CTL and ATL. This makes sure you taper properly and are as fresh as possible for the event without having lost too much form. [Maximise TSB, don’t let CTL fall by 10%]

In theory my fitness curve should dip soon as my training program has an easier week. So, by the end of April 2012, I should have one of those classic graph/curves showing continually rising fitness interspersed with the occasional dip allowing for recovery.  We’ll see (just like the text books!!).

If you spend more time with your stats than training (like me) then you MUST look at this!

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Last Updated on 13 December 2025 by the5krunner

My favourite kit and nutrition

  • Maurten — the race nutrition trusted by elite athletes. Gels and drink mix engineered to be easy on the stomach.
  • Garmin 90-degree charging adapter — the small adapter that keeps your charging cable tidy at the stem. Essential for race day.
  • Garmin charging puck — the fastest and most reliable way to top up your Garmin before a session.
  • Ravemen FR300 — front light that mounts directly under your Garmin or Wahoo head unit. Keeps your bars clean and your beam pointed where it matters.
  • Garmin Varia RTL515 — radar rear light that alerts you to vehicles approaching from behind. Pairs with your Edge or Garmin watch.
  • Stryd — the footpod that brings running power to your Garmin. The single most useful running upgrade I have made.
  • Favero Assioma Pro RS2 — the power meter pedals most serious cyclists end up choosing. Accurate, easy to move between bikes.

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