Critical Swim Speed (CSS) not calculated

Bug Reports
1

Hi everyone,
back in GC I kept track of my swimming progress with CSS. Unfortunatly I cant see it in intervals. My tempo curve is showing, also the checkbox for CS is checked. Any clue what I am doing wrong here?

2

Hi, i’m also interested in the topic.

If you look below the graph at rhythm/swim, it says “CS (critical speed) and D’ are calculated using the 2-parameter model. Intervals.icu uses your best 1k, 2k, 3k, 4k and 5k times while keeping the ones that take between 2 and 15+ minutes.”

So it seems to take the same distances used to calculate running CSS (1k, 2k, 3k, 4k, 5k). Of course, this is not realistic for swimming because swim sessions usually last less than 2k (unless long distance swimmers).

It would be great to fix this issue and use the most common distances to calculate swim CSS (200m and 400m).

3 Likes
3

Any updates here?

1 Like
4

No updates here

5

If I’m not mistaken, .icu does that as ‘Threshold Pace’ , which you can update manually, here:

image

EDIT: I believe this auto-updates from recent swim data as you complete WOs, or at least prompts you that you might want to update it. Not 100% sure though.

Perhaps I’m misunderstanding the question though !

6

We are talking about the general rhythm chart, which is accessed from the menu on the left.

In running tab, it auto-estimates the critical speed based on the times obtained in 1k, 2k, 3k, 4k, 5k. In the swimming tab, graph description indicates that uses the same distances (1k, 2k, 3k, 4k, 5k), which is not realistic for swimming activities witch rarely arrives to 2k (at least for me).

As i don’t have 2k swimming workouts (yet) then it doesn’t estimate my CSS as it needs 2 valid distances (1k and 2k for example).

Garmin description of CSS: “Critical Swim Speed (CSS) is defined as the theoretical fastest pace that a swimmer can maintain continuously without exhaustion, your aerobic swimming threshold. Your CSS is computed using your time for a 400 m or yard time trial, and your time for a 200 m or yard time trial”.

So it seems the issue here is not taking swimming specific distances to calculate CSS and using running ones.

7

I don’t see rhythm/swim. The graph that I have above the quote you give is ‘Pace/100m’.
:face_with_diagonal_mouth:

8

I think you are looking in a workout. You have to enter from the left menu, Rythm (Ritmo in Spanish).

image
image2090×1118 229 KB

9

Nope, that’s where I was looking. I figured it was a language interface issue. In US/Can/GB English it’s ‘Pace’. :+1:

10

Ops, you’re right :sweat_smile:.

And below pace graph, i guess you don’t see CSS, right? Unless you are a true swimmer (not like me :smile: )

11

@david would it be possible to implement a critical swim speed calculation here using the formula
CSS Pace [in secs/100m] = (T400 - T200)/2
where T400 is 400m pace and T200 is a 200m pace within the same activity

There is actually a bit more subtlety to it; as they shouldn’t be overlapping, which comes first can matter, and how long the break between is does as well. But this would be a very good start compared to 1k, 2k, etc bests.

1 Like
12

I think in running critical speed takes the best efforts, doesn’t matter if they come from different workouts, so i guess It could be the same for swimming CS.

So implementing suggested formula would be great to start with.