Understanding Training Peaks

Understanding Your Training Peaks Numbers 

Training Peaks is a powerful training tool for the endurance athlete. To help you make the most of its features here is an article on how to use some of its metrics. These metrics are best combined and displayed within Training Peaks standout feature, the Performance Management Chart (PMC). There are three key markers expressed in the PMC. These markers are the Acute Training Load (ATL), Chronic Training Load (CTL) and the Training Stress Balance (TSB).

Training Stress, Intensity and Fitness

ATL, CTL, and TSB allow us to take both a view into the past of the athlete, a current view of fitness, as well as project into the future when using the PMC. This all goes back to the root metric of Training Stress Score (TSS) which scores a workout based on duration and intensity as a factor of your threshold pace, heart rate or power. 

Chronic Training Load (CTL) or “Fitness”

Think of Chronic Training Load as a measure of your true fitness. It is an ongoing average of your daily training (TSS) specifically looking at the last six weeks or 42 days. This shows your long-term training load and gives a trend line of where an athlete is going. A positive (upward) trending line shows an increasing training load and decreasing (downward line) shows a decreasing level of training load. 

Steady progression is key to prevent injuries, large spikes in CTL correlate with a large amount of training stress. Very fit or experienced athletes can increase their CTL quickly whereas new or older athletes may need to ramp up their training more gradually. Large amounts of training load must pair with adequate recovery to avoid injury, illness, burnout etc. 

CTL and TSS are related and you can use the scale below to determine the intensity of a workout with respect to your current fitness. In this example, we’ll assume the athlete has a CTL of 50.

Hard Workout: A hard workout will result in a TSS score that is 50%-100% above your current CTL (TSS for a hard workout would be 75 – 100 TSS).

Moderate Workout: A moderate workout will result in a TSS score that is 25% above your current CTL (TSS for a moderate workout would be 60-70 TSS).

Easy Workout: An easy workout will result in a TSS score that is 10-25% below your current CTL (TSS for an easy workout would be 35-40 TSS).

From the above you can see that an athlete with lots of time to train can (and should) accumulate much of their TSS through moderate and easy workouts. Those with less time would need some more high intensity training to accumulate more TSS. The mix of intensity of course depends on the athletes stage in their training and their goals.  

Acute Training Load (ATL) or “Fatigue”

Acute Training Load looks at how your most recent training impacts your body. ATL calculates a rolling average of your workout TSS over the last seven days. There is a correlation between fatigue and fitness scores, when your fatigue score is less than your current fitness score, you will normally see a positive Training Stress Balance (TSB) value. However, if you are deep into training you will see a TSB score that is greater than your CTL score.

Steep inclines indicate large loads and will result in a significant and resultant inverse TSB. If you are doing lots of high TSS workouts, you can expect high ATL scores. You can bring down high ATL scores by doing recovery (low TSS) workouts in addition to rest days.

Training Stress Balance (TSB) or “Freshness”

Training Stress Balance is the “ready to race” metric where the more negative the number, the more layers of fatigue an athlete has accumulated and the more positive the number the more recovered and ready to perform an athlete is. This metric has a couple of rough rules that can help guide athletes. However, everyone is different and athletes should rely on their past experiences and recent performances to determine how recovered they need to be to perform well.

  • An ideal TSB range for a peak performance falls between +15 and +25. While zero indicates the athlete has reached a training equilibrium, complete recovery is often needed for peak performance, especially for long-distance racing.
  • The ideal training zone for TSB falls between -10 and -30. It is thought that if athletes push beyond -30 for more than 10 days they are headed for extreme strain. Numbers extending beyond -30 will require consecutive days of rest to achieve the necessary recovery for future performance. For example this is something you might achieve at a training camp, which would then require a recovery week to absorb the hard week of training. 
  • The opposite is true as well, if you start to see +15 to +25 TSB you are extensively recovered and essentially losing fitness.

The PMC is only as good as its data. 

Reliable data creates a clear picture of an athletes fitness. Incorrect zones will undercut any planning and projecting. Propery managed data allows you to maximize the effectiveness and density of your workouts. It is imperative to set your training zones correctly before you can have any confidence in the information being produced. It takes 42 days to get concrete CTL when starting fresh. 

Not all TSS is created equal. 

TSS is the crux of the performance management chart but it is worth noting that it has its flaws. Here is a few examples of how training sessions with the same TSS score would actually feel very different to the athlete: 

A session with intervals of 4 x 10 minutes at a given intensity would feel very different (maybe even impossible) to a session of 1 x 40 minutes at the same intensity. Yet these would both have the same TSS. 

A flat road run at say 5 minutes per KM pace would feel very different to a lumpy trail run at the same pace, again they would have the same TSS. 

A 60 minute continuous swim in a cold choppy sea and a 60 minute continuous swim in a heated pool, both at the same pace giving the same TSS, again would feel very different to the athlete. 

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