The final article in a seven part series in partnership with Verve Cycling - official power crank supplier to the Great Britain Cycling Team - looks at how to understand and analyse your data post-ride.
Not just during the ride
Although an accurate power meter such as an InfoCrank is an incredibly powerful tool for pacing and accurate training while on your bike, the data it gives you is also invaluable for analysing the ride you’ve just done, seeing the impact of your training, planning and even ensuring your form peaks for key events.
TrainingPeaks offers a complete training and analysis package and also hosts all of the British Cycling Digital Training Plans. The key power metrics used on TrainingPeaks are listed and described below.
Average Power (AP)
Your Average Power is simply the numerical average watts you produced for your ride.
Normalized Power® (NP®)
Normalized Power is somewhat complex to understand but takes into account the fact that no ride is perfectly steady. NP takes into account that the physiological response to rapid changes in exercise intensity are not instantaneous, but follow a predictable time course and many critical physiological responses, like lactate production, are curvilinear rather than linear. Basically, NP says what power you would have produced had your effort been perfectly steady. NP is better estimation of the physiological “cost” of a ride than AP.
Intensity Factory® (IF®)
Your IF is the ratio of your Normalized Power to your Threshold Power. The IF is a rough estimate for the intensity of a given ride. It is also great way to compare the relative intensity of a ride or race between different riders assuming variations in a riders’ threshold values.
Variability Index (VI)
Your VI measures how smooth or variable your power output was. It is calculated by dividing your Normalized Power by your Average Power. For long events like a sportive you want your output to be steady, so a VI of 1.05 or less should be your goal. If racing a crit, you may see a VI of 1.2 or higher due to the surges in power.
Training Stress Score® (TSS®)
Based off of the duration and intensity of your session, Training Stress Score is a single numerical value for the level of stress you have put on yourself for a particular training session. You can earn 100 TSS for 1 hour at your threshold power or heart rate. If you are accumulating over 100 TSS per hour, your threshold power or heart rate is probably set too low and needs re-testing. TSS is a great way to keep tabs on how well you’re adapting to your training when paired with the Performance Management Chart (PMC). If workouts are built/planned in TrainingPeaks, as with the British Cycling Digital Training Plans, you’ll know what the TSS of a session should be before you do it. This means you can see the impact of future training.
Performance Management Chart (PMC)
The Performance Management Chart keeps tabs on your daily TSS and will calculate long term training stress (Chronic Training Load or CTL), short term training stress (Acute Training Load or ATL), and the balance between those two which is your form (Training Stress Balance or TSB). As you start to train, you will see your ATL increase based on your short term training. As you start to log more miles, you’ll see your CTL increase over time which equates to your long term fitness level based on your long term training. However, the catch is that TSB or your form will decrease as ATL or short term training stress goes up and in turn raises your CTL or long term training stress. When you get it right, you can bring your CTL up through cycles of increased ATL, then allowing some rest to bring your TSB back up. The trick is getting your TSB back up to where you can feel recovered but still take advantage of all your past fitness. This is how you can peak for key events and it takes a lot of the guesswork and mystery away from tapering and hitting top form when it matters.
With accurate dual sided power meters such as the InfoCrank, you’ll also be able to drill down into the detail of your pedal stroke. You can check for imbalances, smoothness, efficiency and a range of other metrics. This is particularly useful if you’re recovering from an injury or suspect you might have an imbalance between your legs.
Think about a coach
All of this data, metrics and jargon can feel a little overwhelming and confusing at first and it’s definitely possible to suffer from paralysis by analysis. However the more you use your power meter and analysis platform, the greater understanding you’ll get. It can be worth though, having invested in a power meter, taking on the services of a Level 3 British Cycling Coach to help you understand the data and plan your training. This doesn’t need to be a permanent arrangement but can really help you to get the most out of your power meter.