Resources to understand performance metrics

I’d like to understand better the statistics and charts that intervals.icu provides.

Does anyone know good introductory resources (books, online courses, etc…) to help me on that?

Cheers,

Most of the stats have popup help boxes (on click) which often link to blog post etc. explaining the concepts. I have also tried to provide similar links for the various charts. It’s all pieced together from many different sources, so not all in one place unfortunately.

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Yes, I found that boxes, @david. I really appreciate the effort you put here and I can understand (more or less) what each metric means.

But still, I miss the big picture. I cannot tell which ones are the relevant, how they correlate to each other, etc…

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One very good resource is Joe Friel’s books. The Cycist Training Bible has several editions and is considered a must read for serious cyclists explaining most performance metrics in detail.
Training and Racing with a power meter by Coggan and Hunter is equally a good read if you’re intrested in the background of all those metrics.

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These books look like what I was looking for! Thanks a lot, @MedTechCD

What is your goal?
What are you training for and hoping to get out of your training sessions and blocks?
Based on that, certain metrics will be more useful than others.

This is what I want to understand, @Gerald_M.

My level now is kind of low. I am not an absolute begginer, but I considered my level low. I guess anything that is not overtraining will make me improve.

But if I ever want to reach a goal, I’d like to know what are the relevant metrics to look at.

As a beginner your focus should be on

  • Consistency: min 3 rides a week up to 5
  • Developping your aerobic base, ride most of the time at an easy to moderate pace. The biggest beginner mistake is to ride hard all the time. You will get tired, loose motivation and consistency will drop. That makes progress difficult.
  • Enjoy your rides. Don’t start focussing right away on the numbers. Do different things on the bike and discover what you like most/are good at. Don’t start now with structured riding, wait a bit.

While doing the above for at least 3 months, you wil gather data, get to know your body and maybe start dreaming about certain goals.
You will get better pretty fast without tracking any metrics. If you want to, track Power/HRZ2 and decoupling factor. The first one prooves that you can develop more Power for the same internal effort (HR). The second one prooves that you can hold an aerobic effort longer with the same resulting fatigue.
On of the 3 or 4 rides during this period should be a “long” ride. Long here is relative to what you are able now. Long rides must be at an easy pace and the challenge is to add time every week. To develop an aerobic base, the long ride should eventually be 3hours or longer.
After that period of “discovery” and gathering data, identify your goal events and the things you need to work on. Then start with a training plan and more structured riding. Your body will be ready after that initial period and hopefully you will have discovered the joy of riding a bike.

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A lot of people think that CTL is Fitness, but it’s not entirely true. It’s the weighted average of TSS for the last 42 days. The more you ride, the higher your TSS will be. On the flip side there is fatigue (ATL) ans is the weighted average for the last 7 days. This is used in conjunction with other metrics, and shouldn’t be a concern for a beginner.

Each workout should be done with purpose, and complimentary to other workouts, eg. an easy 90-min ride in Z1 (3-zone model) or Z2 (5-zone model) is different to HIT of say 4x4-min at 120% of FTP. Each metric (below) will give a different result.

  • Efficiency Factor (EF), a TrainingPeak defintion, shows on Intervals as Power/HR on your activity header. The higher the number, the more power you can produce for a lower HR, which some say “you are fitter”. This is normalised power / average HR for the workout.

  • Variability is the one just above the Power/HR metric. This is how evenly paced the workout was. It’s calculated as Normalised Power divided by Average Power. An evenly paced ride should be close to 1.00

My 90-min endurance workout (70-80% of FTP, and keeping the HR below 80% of Max) shows Variability Index as 1.02 and Power/HR- at 1.23. When I next do the same ride, I can compare the two, ensuring that other factors are kept the same, eg. fan on/off, 2-3 bottles of hydration, training at the same time of the day, a similar hard workout the day before, or two days, etc. At the same pace, and same HR, I can see if my power is up or down. There’s a benchmark.
image

There are many others, and a good coach will be able to monitor this for you. But why would you want a coach? The help you train for a specific goal, the help you get to that goal, and hold you accountable while guiding you along. If your goal is to get, and stay fit, you need to ask yourself “what is fitness to me?”.

In terms of fatigue, a few signs that you are tired:

  1. How do you feel when you wake up? refreshed or still tired?;
  2. How was the workout? Did you “climb off” the bike, like you could do another interval, or were you ready to fall off?;
  3. Your HR is abnormally high/low compared to your average;
  4. How quickly or slowly does your HR rise/fall when you do a hard workout.

As you can see, there are many different ways to take data (objective) and feelings (subjective) and put them together to get an answer. for hard workouts, like a 4x4-min at 120% of FTP, I like to see HR climb and have minimal cardiac drift, i.e. it should be close to a table top shape and not rising with each minute.

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Another metric that I forgot about, is HRRc

HRRc measures how quickly you recover after a hard effort. It is the largest drop in HR over 60 seconds starting from a HR of at least threshold. The general idea is that, the faster or greater your drop in heart rate, the better your recovery - www.pezcyclingnews.com


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How do you get the HRRc values?
Does it require a special device?
(i’m using the Wahoo TICKR FIT Heart Rate Monitor)

Do a hard effort where your HR goes beyond the LTHR set in settings and then recover. That will trigger a HRRC calculation.

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I did but no calculation

How long was your effort for? Longer than 60 seconds.
Was your 60s effort greater than your threshold HR?
Is your Threshold HR value showing in the Settings (Heart rate) field?

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Turns out i do have some older rides with HRRc values :slight_smile:

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