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Power Tool for Runner

Flat track pace, heart rate analysis and structured workout for power based running sessions

Power Tool for Runner is a data field for Garmin watches that allows:

  • displaying the power, the equivalent pace on a flat track or the heart rate drift in real time or its sliding average over up to 5 minutes
  • displaying a colored background which reflects the power or the flat pace zones
  • programming structured workouts based on the flat pace or the power using Garmin connect’s trainings.
  • using a dedicated view for trail

The data field can be used as second field to the Stryd’s own field Power Zone or standalone. But, in the second case, no data will be pushed to the Power Center.

Connect IQ configuration

Power device

It is possible to to connect to the power device through the firmware or directly through an ANT+ connection.

The direct connection should be used on watches that does not support power sensors (like the FR245). In this case, set “Power Device Source” to “ANT+” and eventually specify explicitly the ANT+ device ID.

For watches that support power devices, set “Power Device Source” to “Integrated” and bind the sensor directly using the sensor discover function of the watch.

Display configuration

2 or 3 values can be displayed on the screen. For a trail activity, there is a separate set of settings.

In general, 3 kind of values can be shown:

  • the power
  • the flat pace
  • the difference between the measured heart rate and a predicted value from the power.

All these values can be instant one or a sliding average over up to 5 minutes. The main field is using the biggest possible font.

A different configuration can be setup for:

  • A normal running session
  • Treadmill run
  • Trail run

Also an alternate configuration can be set for:

  • A training session
  • When the power is less than 25W (pause mode)

Training Zones

The field supports two kind of zones which can be selected by “Training Zones” in the Garmin IQ parameters:

  • Flat pace based
  • Power based

Then it is necessary to fill all zone limits for the power or the pace. The power zones will not be fetched from Stryd’s Power Center.

The zones are displayed in a form of a colored background progress bar:

  • Zone 1: Gray
  • Zone 2: Blue
  • Zone 3: Green
  • Zone 4: Yellow
  • Zone 5: Red

Configuration of the flat pace algorithm

The flat pace algorithm should only be used when running, walking produce a different power profile which has a negative effect on the precision of the pace computation. For this reason, the parameters “Minimum Required Pace” and “Maximum Required Pace” should be adjusted to smallest and highest speed that can be run.

For trail run, the topology of some trail may also influence the algorithm. This is certainly because the power seems no more reflect the effort on some irregular roads or for some hills for example. For this reason, the learning algorithm should be disable for this activity. (Parameter “Disable learning in trail”)

Finally a parameter “Pace Computation History” permits to define how long the algorithm keeps in memory the learned power/pace association. The default is 6h.

Configuration of the heart rate efficiency

For this algorithm, the parameter “Heart rate computation history” permits to set the size of the history. It is per default 6h.

The warmup should be excluded from the analysis since that the heart rate behaves a bit differently as during the rest of the run. The parameter “Skip the first minutes of a session” permits to specify the duration of it to ignore it.

Structured workout parameters

Connect IQ permits configuring the alerts for it:

  • Enabling/disabling sound or vibrations for out of range alerts
  • The parameter “Time before raising an alert” permits to specify after how many seconds an alert is generated.
  • The parameter “Time between an alert repetition” permits to specify how long to wait until the alert is emitted again.

Activity configuration on the Watch

On the watch it is only necessary to add the field “Power Tool” with the same procedure as Stryd’s “Power Zone”.

For structured workouts, it is possible to enable an additional alert on the watch itself. This will create a full screen notification when the power or pace is out of the requested range.

To enable it, you have to do following on your watch:

  1. Edit the parameters of your running activity
  2. Go to the “Alerts” menu
  3. Select “Add New
  4. Select “Connect IQ Data Fields
  5. Select “Power Tool
  6. Exit the settings by pressing several times the back button.

Demonstration video of the watch setup:


Creation using Garmin Connect

To create a power based workout, just use the usual procedure to create workouts with Garmin Connect. Then specify the constrain as followings: Then instead of specifying a constrain, just add to the step a comment formatted as following:

  • For a power based steps, add the power range or a power zone. The power zones values from Garmin Connect are ignored, so it takes the zones configured in the data field.
  • For flat pace based steps, add a comment with a pace range: min:sec-min:sec. For example, 7:00-6:30 to request a flat pace between 7:00 and 6:30. The unit, metric (min/km) or imperial (min/mil) depends on the system settings.

Here a small video of the creation of a workout whose second step has a required power between 45w and 60w:

Creation using Training Peaks, Nolio and Final Surge

It is also possible to create power based workouts using Nolio, Training Peaks or Final Surge account. Just create one and the power based step will then be automatically recognized and will work as if configured through Garmin Connect.


In a power or flat pace workout step, the information displayed are no more following the settings but reflect the workout step’s configuration. The main value is the power (resp. the flat pace) for a power based workout step (resp. for a flat pace based step). The second information displayed is the target range.

The background color is red, if the runner should accelerate and blue if he should decelerate. If in the range, the background color is the default one. A progress bar indicate the progress of the current workout step if time or distance based.

Here the video of the workout execution on the watch:

Calibration run

Flat pace

To get a precise flat pace, it is better to do a first calibration run. The best is simply to run at several speed, from the slowest to the fastest possible, at least 30s for each. This should be enough and the result will then be more accurate run after run.

Read this article to know a bit more about the flat pace and its computation.

Heart rate efficiency

The heart rate efficiency consists of predicting the heart rate from the power and measuring the difference with what is measured. A positive value of 3.0ppm means that the pulse was 3.0ppm lower as what is expected for this effort.

To get an accurate information, it is necessary to run at least 10 times and mix intervals with long runs to learn the whole palette of running configurations.

Read this article to know a bit more about the heart rate estimation.

Offline analysis

For an offline analysis, Power Tool record the flat pace for the complete session and for each lap. The heart rate analysis is displayed in the form of the difference with the estimated vs the measured in a real time graph. All this can be consulted using the web site Garmin Connect1.

Additionally, on start, the field open a web page with additional information. Actually, it provides a calculator which permits to compute the race time for a dedicated power. In the future, this page will be extended to provide more analysis.

Software Version - Change Log

  • 2.0.1: adding Enduro watch
  • 2.1.3: computing the heart rate efficiency for a session or for a lap
  • 2.2.6: support of Training Peaks workouts
  • 2.2.17: estimation of the sensation of a session
  • 2.3.10: progress information of workout steps
  • 2.4.2: New color scheme with higher contrast
  • 2.4.4: Recording the power into the .fit file
  • 2.5.4: New setting when running a structured workout and new model for the HR estimation (all previous data need to be recomputed)
  • 2.6.20: Computation of the vVO2max and detection of incoherent HR.
  • 2.6.21: Fenix7 and epix 2 support
  • 2.6.54: Possibility to display only one value and experimental speed gain computation
  • 2.6.7: New algorithms to support trail runs
  • 2.8.3: Support of power zones and power constrains defined in workouts defined through Garmin connect.
  • 2.8.4: Disabling notifications notification when the watch is in pause mode.
  • 2.8.6: Comments for setting power zones are no more supported
  • 2.8.12: Progress bar of the current workout
  • 2.8.15: Support of HR analysis on treadmill and trail runs.
  • 2.8.44: Possibility to display power zones and flat pace zones numbers
  • 2.8.50: New HR prediction algorithm. Customization of the displayed data when stop running.
  • 2.8.58: Computation of the equivalent distance on track

  1. The mobile edition has actually some issues and do not always display the data from the intervals of custom fields. ↩︎

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