How to train with a power meter - part seven: how to analyse long-term trends in your training
Power meters aren't just for short-term gains - here's how to analyse and spot long-term training trends
by James Spragg
Power meters are the gift that keep on giving. And by that I mean, unlike a new set of wheels or a new aero helmet which will only give you advantages to a set point, a power meter can be used to continuously monitor and improve performance.
By analysing long-term trends, you can see if you are on track and if everything has progressed as expected over time, alongside analysing just how much you have improved.
We’ve already looked at how to set up a training program and how to analyse individual training sessions, so how can you analyse your long-term performance trend?
Let’s take a closer look at reading, analysing and informing your future training using either Training Peaks or Strava.
Performance Management Chart
TrainingPeaks’ Performance Management Chart – or the Fitness and Freshness graph if you use Strava – is the key tool for tracking long-term fitness and progress.
The chart offers a measure of fitness, fatigue and form over time, according to how your training load has been scored (i.e TSS in TrainingPeaks or Sufferscore in Strava). The scores are averaged across a number of different time periods to give you those measurements of fitness, fatigue and form.
I should stress here, however, that in order to ensure your TSS score is as accurate as possible (and therefore your performance management chart) your FTP needs to be correct within the TrainingPeaks.
In the graph above, you will see there are three different coloured lines: blue represents Fitness, or Chronic Training Load; the pink line shows Fatigue, or Acute Training Load; and the orange line shows your Form or Training Stress Balance.
There are also two dots – red for your TSS score and blue for your intensity factor – for more on those, see my advice on analysing a training file, or read on to learn how to decipher those three lines.
Blue line – Fitness/Chronic Training Load (CTL)
CTL indicates the amount of training you have done, and therefore how fit you are. It is calculated as a rolling average of your TSS scores across the previous 42 days, but is weighted in favour of your more recent workouts.
A common mistake when studying CTL is to assume a higher CTL equates to better performance on the bike. This is not the case and, in fact, research has confirmed a high CTL score doesn’t necessarily equate to higher power outputs.
I have seen countless athletes chase a high CTL score, thinking it will equate to better performance, only to find themselves over-trained and, consequently, under-performing. Don’t fall into that trap.
CTL is very specific to the individual and the range that works best for you – i.e the greatest amount of training you can handle and still perform well – is dictated by numerous factors, such as training history, ability to recover, genetics, and external influences such as your job and social life to name just a few.
As a result, I tend to describe CTL as long term fatigue rather than fitness when discussing it with clients; you need a certain amount of fatigue to give your body the stimulus to improve, but too much and you will find yourself over-trained.
As with any fatigue eventually you are going to need to give your body time to recover and this is where good periodisation of your year comes in (see creating a training plan).
So how do you find the right CTL range for you? The best advice is to keep an eye on other factors alongside your CTL – How do you feel? How motivated are you? Is your power increasing or decreasing? Has your perceived rate of effort increased for the same power output?
All these factors need to be given equal billing to your CTL when tracking your training program in the long-term.
Bottom line: CTL aims to quantify your fitness, based on the last 42 days of training.
Pink line – Fatigue/Acute Training Load (ATL)
ATL is very similar to CTL, but works on a rolling average of the last seven days and aims to quantify how fatigued you are on any given day.
The theory is you won’t yet have fully adapted to the sessions you have done over the last seven days, and therefore are carrying the fatigue from those sessions rather than the form.
Again, ATL is weighted towards your more recent training sessions, but I must stress it isn’t particular accurate – it’s the best measure we have as coaches, but that doesn’t necessarily mean it’s correct.
Every athlete responds differently to training, and the same athlete will also respond differently to different training stimulus.
Therefore, ATL as with all figures in a performance management chart, should be treated as a guide to be taken into account alongside other factors.
ATL, for example, doesn’t take into consideration how well you are recovering from sessions. If you are away on a training camp, and can spend each afternoon on your bed after each ride, it may be that you are recovering particularly well but your ATL won’t take this into account. In this scenario your ATL may be artificially high.
Likewise, if you have slept badly, had a late night, taken a flight, had a stressful day at work or encountered any other situation that may impact on recovery then this again won’t be reflected in your ATL score, and it may seem artificially low.
This is very important because an inaccurate ATL will affect your Form / Training Stress Balance score.
Bottom line: ATL quantifies your fatigue levels, based on the last seven days of training
Orange line – Form/Training Stress Balance (TSB)
Speaking of your TSB score… this represents the difference between CTL and ATL, serving as a measure of how good you will feel on a given day.
You will normally feel at your best on the bike when you are fully recovered from the training you have done recently. Essentially, when you have done less over the last week than you have on average across the last six weeks, your ATL will be lower than your CTL and therefore your TSB is positive.
If you are fatigued because you have done more training over the last week than you have done on average over the last six weeks, ATL will be greater than CTL and therefore your TSB will be negative.
Every athlete will have a range in which they perform well. For some this may be positive for others it may be negative. However, because of the issues already identified in CTL and ATL scores, even for the same athlete this range is not fixed.
For example, if we take the above scenarios - you are away on a training camp and are recovering very well after each session because all you need to do each afternoon is lie in bed then your ATL will be artificially high and you should be able to perform well at lower TSBs than normal.
On the other hand, if you are in a stressful period at work then it may be your ATL is artificially low and the TSB range you perform well in will be much higher than normal.
It’s also worth noting the TSB range in which you perform best is discipline-specific – just because you’re at your best in road races with a TSB between 0-10 doesn’t mean that will be the best range to aim for ahead of a criterium or track points race.
TSB is probably most useful when tapering for an event, or determining if it is time to add a recovery block into your training plan.
For each of the athletes I work with I have a rough TSB range they can work to on an average week, and I use this alongside the feedback I am getting from the athlete themselves and the data from their individual training files to make a decision on whether we need to include some extra recovery or not.
Likewise when tapering for an important event I will aim for an increase in TSB, again taking into account the feedback and data from the athlete to adjust the taper to ensure they feel at their best come race day.
Bottom line: TSB quantifies how good you are going to feel on the bike on any given day
This is a measure of how quickly your CTL is rising. When training you are looking for a steady progression in training load allowing your body to adapt to the training as you go along.
This goes back to my piece on creating a training plan. If you have a nice steady ramp rate – i.e. a nice steady progression in your training load then your form will look something like the top graph.
However, if you try and progress the CTL too quickly i.e. your ramp rate is too high you won’t be allowing your body adequate recovery and your form will look something like the bottom graph.
Ramp rate is again very individual to each athlete. The maximal tolerable ramp rate, and also the length for which that ramp rate can be sustained, both vary between individual and also during different periods for the same athlete.
As with all the measures described in this piece, as a coach I will use it as part of the decision-making process and not as the sole basis for decisions on an athletes training plan.
Bottom line: Provides a measure of how quickly your training is progressing
There is a famous saying that tells us ‘all models are wrong… but some are useful’ and this describes perfectly the performance management chart. As a coach or athlete, it's something you need to use as a guide not as gospel.
You also need to listen to your body and how you are feeling. It is for this reason I get all my clients to report back to me each day how they are feeling and how motivated they are.
I use this information alongside the data from their power meters and their personal performance management charts to make decisions when setting the next block of training.