What is CSS

CSS is an acronym for Critical Swim Speed. It's an approximation of your lactate threshold speed and you can find it by doing a couple of swimming tests. All you need is a stopwatch! It's not precisely the same as your swim lactate threshold, but it will be within a couple of seconds per 100m, which is plenty accurate enough to guide your training.

 

The Test

Follow the protocol below and record your 400m & 200m Time Trial times.

  • Warm-up:

    • 1 x 300m relaxed front crawl swim.

    • 4 x 50m front crawl swim (as 25m fast/23m easy) with 10s rest after each 50m

    • 4 x 100m relaxed front crawl swim with 20s rest after each.

  • 400m time trial

  • Rest for 4 - 5 minutes making sure you have fully recovered.

  • 200m time trial

  • Warm Down:

    • 1 x 100 relaxed choice swim

 

CSS Calculator

Critical Swim Speed Pace Calculator

Pool length:

Your 400 Time

Your 200 Time

Your CSS Pace: /100


 

Update Your sWIM sPEED Training Zones

Don’t forget to update your Threshold Swim Pace in TrainingPeaks and review your Swim Speed Training Zones.

Go to your settings, and ‘Zones’.
Under ‘Speed/Pace’, Add or Edit your ‘Swim Pace’, using 'Threshold Speed',
Select ‘MyProCoach Swimming' for the zones. This will give you your training paces as below:

Zone 1 - Easy
Zone 2 - Steady
Zone 3 - Moderate
Zone 4 - Hard
Zone 5 - Very Hard

 

The Benefits

  1. CSS is a race-specific training pace. It may not make you the fastest 50 or 100 swimmer, but it will train you to sustain a moderately high speed for longer distances. Especially important as the race season approaches.

  2. CSS training teaches you about pace awareness and enables you to develop a feel for your sustainable race pace.

  3. Once you know your CSS pace, you can use set a time on your Watch or use a Finis Tempo Trainer Pro to help you train. Dial-in your CSS pace and stick to the beeps every lap so that you can maintain perfect pace.

 

CSS Sample Workouts

Once you’ve worked out your CSS pace, the training possibilities are endless. You could start off by trying these four simple workouts. You can shorten them if you’re not quite ready for 2000 meters yet. Don’t forget to include a warm-up (400m) and warm down (100 to 200m) too.

  • 20×100m with 15-second recoveries. All at CSS

  • 10×200m with 20-second recoveries. All at CSS

  • 5×400m with 30-second recoveries. All at CSS

  • 3×600m with 45-second recoveries. All at CSS

In addition to CSS training, it’s also important to strike a balance between speed, threshold, and endurance workouts in order to meet the needs of your target races. Technique work and open water training are equally important too!

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