A 400 and 200 test can give a coach a repeatable reference for training pace. Treat the result as a planning input, not a complete picture of an athlete.
Keep the conditions consistent
Use the same pool length, stroke and timing method. Record the conditions alongside each result so a later comparison is meaningful. The coach should choose the warm-up and recovery appropriate to the swimmer.
Record both swims
Time the 400 and the 200 in seconds. Keep the efforts separate, with recovery directed by the coach. Check the entries before using them to update a profile.
Calculate the reference pace
CSS pace in seconds per 100 metres = (400 time − 200 time) ÷ 2.
For example, 320 seconds for the 400 and 150 seconds for the 200 gives 85 seconds per 100 metres: 1:25 / 100 m. These are illustrative times, not a recommended target.
Put the result in context
Review the profile in Test sets and Pace Studio. Keep technique, current readiness and the purpose of the session in the coaching decision. A single test should not automatically determine every training target.