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What is Critical Swim Speed?
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. This test can be done in a 25 m pool or a 25 yard pool.
Recording a Critical Swim Speed Test
Garmin® watches with this feature have a CSS test workout preloaded on the watch.
NOTE: The following steps are provided as general instructions. For specific steps, and to determine if your watch supports Critical Swim Speed, refer to your owner's manual.
Select Pool Swim Options.
Select Training.
Select Workouts.
Select Critical Swim Speed.
Select Do Critical Swim Speed Test.
The watch will show a preview of the steps in the workout. When you are ready to start the workout, select Do Test. At the end of the workout, the watch will compute your CSS and display it in your User Profile.
It is recommended to repeat the test approximately every 8 weeks to track your improvements. You can also use your CSS pace to determine training paces. There are many online publications outside of Garmin that provide more information about CSS and how it can be used when training. You can read more about CSS by searching for "Critical Swim Speed" online.