how does the “training load” measurement work on Apple Watches?

If Apple Watches have been used for running, cycling or weight training for a long time, the absence of certain functions made them much less optimized than dedicated sports watches like Garmin watches.

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With watchOS 11, however, Apple corrected one of these shortcomings by introducing a new data: training load. But how does it work and what is it used for? This is what we will see in this complete file.

What is training load?

The training load is a fact well known to athletes. This is the total load of your sports training, generally given by a score which will depend on the platform used.

Most sports watch manufacturers already offer such a measurement, whether Garmin, Polar, Coros or Suunto. Furthermore, the social network Strava can also offer a similar measurement with its relative effort. Even Fitbit got in on the act by offering, since August 2024, its own cardiac load score.

Traditionally, connected watches will be based on two criteria to measure the user’s training load: the duration of the session and its intensity, based on the measured heart rate.

Furthermore, the training load can be smoothed, like what Apple’s measurement offers. It will thus increase on training days and decrease slightly on rest days, but it is an average value that will be given.

What is the ideal training load?

There is no ideal training load for all users. This value only makes sense when put into perspective in relation to previous days.

Ideally, the training load should increase little by little, week after week, by around 5 to 10%. Indeed, too strong an increase could lead to overtraining and therefore injury. A training load that does not change amounts to maintaining one’s state of form. Finally, a training load that continues to decrease will lead to a loss of fitness level, and thus to detraining.

On Apple Watch, the training load is displayed as a colored curve. Each point represents your training load for the day. Next to it, we will find a white line which represents the training load of the previous month.

Depending on the location of the point in relation to the white curve, the training load will then be defined:

• well below: -51% and less
• below: between -21% and -50%
• stable: between -20% and +20%
• above: between +21% and +50%
• well above: +51% and more

With this indication, you are then free to know if you could train more to progress, if you are in a good zone or if you are at risk of injury and should take it more slowly.

To evaluate the load of a specific workout, the American brand indicates that it uses several criteria. In addition to exercise duration, Apple also assigns a Perceived Exertion (RPE) rating to each workout.

This is a score from 1 to 10 which will automatically judge the effort measured based on several criteria:

• age ;
• size ;
• weight ;
• localisation ;
• heart rate;
• altitude.

Concretely, the score is supposed to reflect the user’s effort at the end of their session:

• 1, 2 or 3: easy, “ not difficult, I could have continued for a long time » ;
• 4, 5 or 6: moderate, “ effective but pleasant, I could have continued for a while » ;
• 7 or 8: difficult, “ difficult and painful, I could not have continued for long » ;
• 9 or 10 : maximum, «very painful, I had difficulty finishing ».

The Apple Watch will automatically determine the RPE after each session based on several criteria for endurance sports. However, it is still possible to modify the RPE score for your session, or to indicate it manually for workouts that do not offer it automatically.

The importance of the measurement of perceived effort (RPE)

Perceived effort measurement is the most important criterion for determining training load on Apple Watch. It must be said that the training load is essentially based on two criteria: the duration of the session and the RPE.

In fact, by changing the RPE as calculated by the Apple Watch, it can significantly change the training load for the day.

Overall, RPE as predicted by watchOS 11 correlates quite well with perceived effort for endurance sports. We will therefore simply adjust it upwards in the event of a particularly difficult session, for elements which could not be measured by the watch, such as aches or stress.

On the other hand, for sports in which the RPE is not calculated automatically, it will necessarily be necessary to rely on its feeling so that the training load is analyzed correctly.

A training load that must be calibrated

Apple’s training load system does not give any absolute value, unlike what Garmin, Coros, Suunto, Polar or Strava offer.

Here the training load is only shown as a percentage compared to the previous 28 days.

Logically, this means that you will have to wait 28 days before the training load is actually usable on Apple Watch. During these 28 days, you will indeed have the training curve, but no notion of progress compared to the previous period.

Apple Watches compatible with training load

Training load measurement is offered on all Apple Watches compatible with watchOS 11. This functionality can therefore be found on:

To take advantage of the training load on Apple Watch, you must go to the “Shape», then select the curve icon, top right.

On iPhone, the training load is also found in a dedicated section of the application “Shape».