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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Open Water Dread

 Open Water Dread!


It’s the time in the UK when triathletes are starting to consider their first open water dip. If you are racing soon then of course, you need to. I wouldn’t advise rocking up to your first race having not had a few dips outside no matter how experienced you might be. But what if this is your first season of triathlon, SwimRun or first open water event? Then this is a BIG deal and probably the cause of most of your anxieties about the training ahead. Here’s my tips on how to conquer your fear of open water swimming.

Manage your expectations, your first swim won’t go well if you expect to swim like you can in the pool. You will panic, you won’t swim in a straight line and you will forget all the technique you worked on for the last six months. So don’t go to your swim spot expecting to swim a PB just because everyone has told you how much faster you are in a wet suit! Change your goals, baby steps, below is a more manageable approach:

  • Aim to stay in the water for 5-10 minutes.


  • Plan to just move around to keep warm by whatever means feels the least scary e.g. breaststroke, on your back or head up freestyle.


  • Let the cold water shock subside until you can keep your breathing under control. Then get out, job done, you survived your first open water dip!


  • Next, repeat these short dips but add extra little challenges such as aiming to move between features for example from the shore to a buoy and back.


  • If you are not confident putting your head into the water then introduce it gradually. Swim head up freestyle and then every five strokes put your face in and blow bubbles, then every 3, then 2 etc.


  • When you can continuously swim head down just breathe when you need to. You may be really comfortable breathing every 3 or 4 strokes in the pool but initially you may need to breathe more often and sporadically in open water, this is fine, whatever feels the most natural and relaxed.

Once you are swimming comfortably with your head down you will need to use the most important open water skill, sighting (looking up to see where you are going). Make sure you practice this in the pool first! Just because you never swim into the lane rope in the pool does not mean you will swim straight in open water. I love to try this test when coaching in the pool, give it a try; line yourself up in the middle of the lane, push and glide down the centre, then close your eyes and start swimming, stop when you hit the lane rope. Most hit the lane rope between 10 and 15 metres into the length, meaning if you don’t look up at least once every 10 metres outside, you will swim further than you need to. If in doubt look up and don’t be afraid to look up multiple times within a few metres to really lock on to your target. If you go off course in a race you will likely panic, swim hard to get back on course and dig yourself into a hole as you expend unnecessary energy and zig-zag your way to the exit. The fastest way from A to B is a straight line, even if you have to stop and get your bearings it will still be easier than swimming off course.

If you have the time try to add open water swimming as an extra swim session. That way you don’t have the pressure of covering the same distance you might in the sacrificed pool session, particularly while you are still building your confidence. Look to add some structure to that open water session such as distances at different effort levels, trying different breathing patterns or trying to swim near others. All useful skills in a race and it will take your mind off any open water anxieties.

Remember, you are not alone! Most triathletes have been through all of of the same fears. The more times you get in open water the easier it will get, be brave, persevere and STAY SAFE!