Critical Swim Speed is the swimming equivalent of a runner's lactate threshold — the fastest pace you can sustain for a prolonged effort. It is estimated from two time trials: CSS = (400 − 200) ÷ (time for 400m − time for 200m), giving a speed in metres per second. Training sets are then prescribed relative to your CSS pace per 100m, with threshold work at CSS, speed work faster, and recovery slower.
Key points
- Swimming's threshold pace
- From 400m and 200m time trials
- CSS = 200 ÷ (t400 − t200) m/s
- Used to set training paces
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