CSS Swim Test

Recently, I only had time for a shorter swim, so I figured I'd try something "all out" and looked up the old idea of finding my ideal training speed through the CSS (Critical Swim Speed) idea of swimming. This was something that Robby B turned me on to in 2014.

I first posted about it here saying this:

They say to swim an all-out 400, rest and swim easy a bit after that, and then do an all-out 200. Find the difference between your time in the 400 and 200, and then divide that by 2 to get your CSS pace / 100.

For example, here are my numbers: I swam my 400 in 6:10. Then I did my 200 in 3:00. The difference between those is 2 times is 3:10. Divide that by 2, and my CSS training pace should be 1:35.

The idea is to NOT go "all out" for every interval swim, because that's less beneficial. But instead, swim your CSS pace and then take less rest. That way (supposedly), you're swimming at a pace that will help you become faster and build your endurance.

I retested it later in 2014 and my CSS pace had dropped from 1:35 to 1:30.

But since then, I've been slowly adding MORE rest and swimming closer to ALL OUT during intervals. That's ANTI-CSS swimming. So maybe I should try shortening my rests and easing up on my efforts a bit to see if it helps make me any faster.

Anyway, when looking for quicker/harder swim workout recently, I figured I'd "retest" my CSS pace. I did a 200 warm-up, took a 1:00 breather, and then did 400 as close to all-out as possible. That clocked in at 6:06 (1:30, 1:34, 1:35, and 1:27). After a 1 min rest, an easy 100, and another 1 min rest, I then took off for an all-out 200, which took me 2:58 (1:29 and 1:29). Doing the math (6:08 - 2:58 / 2) gave me a CSS swim pace of 1:35. And I used this website that told me it was 1:34. That website also shared training zones based on my time:

I don't really know what to do with those "zones" above, but whatever. That website also noted a few workouts to do with your CSS pace:

I like the idea of #1 - those are easier 100s than I'm used to, but MORE of them (which is kind of the point here). Workout #2 could work for me too, but I usually do 200s around 3:08 anyway, which is my CSS pace of 1:34/100. So I don't know that I could do 10 when I usually do 7 or 8.

But I could NOT do workouts #3 or #4 at my CSS pace - that's too far and too fast for me to be able to tackle! I mean, I just did an all-out 400 in 6:06, and this is telling me to do 5x400 all at 6:16 (1:34 pace). I might be reading this workout idea incorrectly, because that's NUTS. Maybe I'm supposed to slow my pace to a different zone for those longer workouts? That'd kinda make sense, but that's not stated anywhere.

Anyway, check out this website for a bit more on CSS and see if it's right for you!