How to display stroke type (Breaststroke, Freestyle, Backstroke) in swimming charts?

[abernard]

Hello,

I have created an activity chart for my swim sessions that allows me to visualize not only the paces but also the distances and number of lengths completed for each interval, with information about distance, deviation from average pace, and number of lengths included in the tooltips that appear when hovering with the mouse.

Each bar is colored according to its pace value on the color palette. I have also added a subtle greyed-out area for each recovery or pause detected between two efforts. When hovering over this area, a tooltip displays the duration of the pause.

I would like to add the type of stroke (breaststroke, freestyle, or backstroke) detected by my Coros watch, but I don’t think this data is collected by Intervals.icu, or perhaps I don’t know the name of the variable stored in the database.

Could you help me with this?

Thank you very much.

Best regards,

[MedTechCD]

@abernard

I would like to add the type of stroke (breaststroke, freestyle, or backstroke) detected by my Coros watch, but I don’t think this data is collected by Intervals.icu

It is not implemented by default but you might be able to add it as a ‘Custom Stream’ if it is in the FIT file.
First check the FIT file with FitFileViewer.com to see if you can identify it.
Then in Intervals, go to Charts, Custom Streams, Add Stream and see if it is listed in the Record Field dropdown.

[abernard]

@MedTechCD The data is indeed present in the FIT file, but it is not listed in the Record Field dropdown

let strokeType = iv.swim_stroke || iv.customFields?.swim_stroke || "Not specified";

I tried to add code to retrieve this information, but without success.

Custom field scripts for intervals do not appear to have direct access to the “length” messages in the FIT file (where swim_stroke is located).
The structure of the objects accessible within the interval script only provides access to interval properties, streams, and certain activity aggregates, but not to the raw “length” messages.

[R2Tom]

You can get the message and swim stroke with that kind of code on the console:

{
for (let m of icu.fit) {
    if(m.event?.valueName === "LENGTH") {
         console.log(m); //the message
         console.log(m.swim_stroke) // swim stroke
    }
  }
}

You have to tick the „Process fit file Message“ on the „Type“ Tab, that this works.

[abernard]

Thank you @R2Tom for this idea.
Admittedly, in the interval field editor, I can collect this data from icu.fit, but I can’t use it in my activity chart script-or at least, I don’t know how to do it.

[R2Tom]

Yeah, that’s a current limitation of the activity charts they do not have access to the fit part of an activity. Would be great if that cloud be possible some day @david
The only workaround I am aware of is to write the necessary parts in a custom field. From the activity chart you can then read the custom field.

I did it that way for segment laps some time ago.

Plotting Segment Laps from a FIT file

I finally created two custom activity charts, one bar chart and one table chart for segment laps in a FIT file. Since I use a Wahoo Bolt for my rides, I was always surprised that I couldn’t display the completed Summit Segments afterwards. However, these are written to the FIT file as Segment Lap (just like Strava Live Segments, by the way), so it is still possible to evaluate them. With the integration of Plotly in intervals.icu, it is also possible to plot a table so that I can also display t…

[abernard]

Thank you very much, @R2Tom . Your suggestion allowed me to fix the script for my activity chart and achieve the graph result I wanted.

[...]

// Update stroke style mapping according to standards
const STROKE_MAPPING = {
  "1": "Breaststroke",
  "2": "Freestyle",
  "3": "Backstroke",
  "4": "Medley",
  "undefined": "Unspecified"
};

const STROKE_COLORS = {
  "Breaststroke": "#e74c3c",
  "Freestyle": "#3498db",
  "Backstroke": "#2ecc71",
  "Medley": "#9b59b6",
  "Unspecified": "#7f8c8d"
};

 [...]

  // --- Raw SwimStroke content display ---
  console.log(`Interval ${c} - iv.customFields.SwimStroke:`, iv.customFields?.SwimStroke);

  // Detect stroke type: first from customFields, then via lengths
  let strokeValue = undefined;
  if (iv.customFields && iv.customFields.SwimStroke) {
    // Priority to customFields data if available
    strokeValue = iv.customFields.SwimStroke;
  }
 [...]

I have made it public.

I’m not a good swimmer, but I’m taking lessons with a coach

[abernard]

@R2Tom

You can get the message and swim stroke with that kind of code on the console:

I modified the code as follows.

if (typeof swimStrokeMap === "undefined") {
    // Define only if it doesn't already exist
    swimStrokeMap = {
        "0": "Freestyle",
        "1": "Backstroke", 
        "2": "Breaststroke",
        "5": "Medley"
    };
}

for (let lap of icu.fit.lap) {
    if (lap.swim_stroke !== null) {
        // Convert to string then extract
        const indexStr = lap.message_index.toString();
        const distanceStr = lap.total_distance.toString();
        const strokeStr = lap.swim_stroke.toString();
        
        // Extract numeric values
        const indexValue = indexStr.includes('=') ? indexStr.split('=')[1] : indexStr;
        const distanceValue = distanceStr.includes('=') ? distanceStr.split('=')[1].replace('(m)', '') : distanceStr;
        const strokeValue = strokeStr.includes('=') ? strokeStr.split('=')[1] : strokeStr;
        
        // Convert swim_stroke value to readable name
        const strokeName = swimStrokeMap[strokeValue] || `Type ${strokeValue}`;
        
        // Display in the requested format
        console.log(`index=${indexValue}, distance=${distanceValue}, swim_stroke=${strokeName}`);
    }
}

[Urs_Leuthold]

Hi, I get the following error message:

Swim Interval Analysis
ReferenceError: “lengthsData” is not defined
Interval 1 - iv.customFields.SwimStroke: undefined

I try to debug it with my own activity, but maybe someone knows, what causes the error.

[david]

@abernard

Custom field scripts for intervals do not appear to have direct access to the “length” messages in the FIT file (where swim_stroke is located)

Yes everything in the fit file is only available to custom streams and activity fields with the “Processes fit file messages” box ticked. And these only run when the file is re-processed, not just analysed. Intervals.icu keeps the original file in slow cloud storage, and only summary info in a local database. Currently Intervals.icu has more than 16TB of data in cloud storage. Thats way too much to keep in a local db.

[Nik_Om_Cinderella_Ri]

@david

16TB of data in cloud storage

That’s like just 1x Seagate IronWolf 16tb HDD

Just One

[abernard]

@Urs_Leuthold
You need to add a custom interval field, include it in the data tab, and manually select the swim stroke from the dropdown menu. Once this data is available, the script will use it to build the chart. I hope these explanations are the reason for the error.

[David_R]

The automatic one I made also seems to work with this chart. It does have some limitations though, as I just made it work based on my simple swims.

[ThomasGugler]

i exactly added this new field..and same error is not resolved..

ReferenceError: “lengthsData” is not defined

Interval 1 - iv.customFields.SwimStroke: undefined

[abernard]

Integrate the declaration of lengthsData into the data and mappings initialization, and before the main loop to fix the issue:

const lengthsData = activity.lengths || [];

[ThomasGugler]

what is the script for that field?

[abernard]

[abernard]

Author of the “Swim Interval Analysis” chart, I created a fork under the name “Swim Session Analyzer”.

This chart provides an interactive visualization of swimming workout data, focusing on intervals, pace, stroke types, and pauses. It automatically detects each interval’s swim style and displays performance metrics such as average pace per 100 meters, stroke count, and distance covered. The chart highlights the fastest interval and allows users to filter the view by stroke type, updating summary statistics and annotations accordingly. Pauses between intervals are visually represented, with detailed tooltips offering insights into stroke efficiency and deviations from average pace.

To use this script, you must first add a custom interval field to your data, ensure it is visible in the data tab, and manually select the swim stroke for each interval using the dropdown menu. The swim strokes must be added in the following order: Breaststroke, Freestyle, Backstroke, Mixed, and Unspecified. Once this information is provided in the specified sequence, the script will automatically incorporate it to generate the chart and display the relevant performance metrics.

This ensures that swim stroke data is consistently organized and interpreted by the script, providing accurate filtering and visualization for each stroke type.