This easy guide will help you to understand what the graphs and numbers mean, and allow you to have a more constructive discussion with your coach about your fitness trends.
1. CTL – the blue line
CTL is also called Fitness since it is a is a rolling 42-day average of your daily TSS.
It indicates how much training load you are currently managing. If your Fitness rises you are capable of handling a higher training load and therefore are more fit. And you may also assume the opposite.
This number depends on you and how much training you are doing and are capable of, but unless you are ill or injured it should be generally increasing with consistent training. As CTL increases, fatigue (ATL) also increases.
If you are in a serious period of training, such as the last 12 weeks before an A-priority race, you should see the line generally rising.
During such periods of focused training you may want to see your Fitness rise by 5 to 8 points per week, excluding rest and recovery weeks spaced every third or fourth week. During rest weeks your Fitness should be allowed to decline.
2. TSS – the red dots
This is your training stress score.
It’s basically how hard or stressful your last workout was and is a combination of the intensity factor and duration of the workout.
How much training load you are capable of handling differs from athlete to athlete. Some people can easily manage a very high Fitness, such as say a 150 TSS per day average. Others would quickly wind up overtrained from attempting to do that.
You will see different TSS values: TSS based on power rTSS based on run pace sTSS based on swim pace
hrTSS based on heart rate
3. ATL - the pink line
This is Acute training load or fatigue.
This an average of your last 7 days of cumulative stress. It will climb sharply in response to high TSS and drop when you are in a period of rest/recovery.
4. TSB – the yellow line
TSB is training stress balance and is a way to describe ‘form’. In a single phrase, ‘form’ refers to race readiness.
It is todays CTL MINUS todays ATL
It can be either a negative or a positive number depending on which is greater- Fitness or Fatigue. If Form is negative you are likely to be tired and probably not race ready. If Form is positive then you are probably rested and perhaps on form— if it doesn’t get too high.
So what does this mean to you?
When you are tapering and peaking for A-priority races your form should be at around plus 15 to plus 25 on race day. This is for MOST athletes (you may be different!).
Usually when it’s below negative 10 you’re probably too tired to race well. You’re not “on form.” That may be OK for a C priority race. For a B race you will probably want your Form trending positive and between negative 10 and 0.
Keeping Form in the negative 10 to negative 30 range when the training is hard and focused is a very productive and healthy range. This could be, for example, in the serious training weeks of the base and build periods.
If you spend much time in the -10 to +10 Form range your training is stagnant, and this range is best avoided.
Pushing your Form below negative 30 greatly increases your risk of injury or illness. Make sure you are adding in some rest days or days with low TSS sessions.
If your TSS is 25 or above, your training is much too easy and you’re losing a lot of fitness. There could be some good reasons for this (illness/injury) but be mindful of these.
5. IF
Intensity factor. This is a value of how intense your workout is in relation to your FTP (the max effort you can sustain for an hour), whether on the bike, run or swim.
There are a few ways to measure FTP (20min bike test, 10k run, 100m swim TT).
IF for anything over an hour should always be <1.0 as your 1-hr all out effort would be 1.0
6. VI
Variability of workout and only relevant if you have a power meter. This gives you an idea of how evenly paced your workout was. A value of 1.0 would indicate the most evenly paced possible. For example if you were doing at Time Trial race anything under 1.05 is ideal.
7. EF
Efficiency factor. You would use this to compare similar workouts over a period of months to see if your efficiency is improving. It is calculated by dividing your Normalised power or pace by your heartrate.
Ideally your output (effort) should increase over time for the same heartrate and this would give you feedback on that.
8. Pw:HR, Pa:HR
This refers to something called decoupling which is how your HR increases over the duration of a workout – a normal thing to happen. But it gives an indication of your aerobic fitness.
Anything above 5% indicates that more aerobic training is needed. But you must only look at this for a training session that is the same as your race distance as it is very specific.
It is also affected by caffeine, dehydration and lack of sleep.