Critical Swim Speed
Critical Swim Speed (CSS) is the swimming speed that can theoretically be held for an extended time, usually derived from 400 m and 200 m time trials.
Definition
“Critical Swim Speed” (CSS) is the swimming speed that can theoretically be sustained for an extended duration without progressive fatigue; it is the swimming equivalent of critical power. Classically it is calculated from a 400 m and a 200 m maximal time. obseed works with a variant in which the 400 m are swum after a defined pre-fatigue set.
Why it matters
In swimming there is currently no practical method for analysing metabolism under load directly. Spiroergometry in the pool is limited to a handful of research labs, lactate sampling is cumbersome and interrupts the flow. Speed and distance therefore remain the only reliable quantities for documenting progress and building training zones.
CSS provides a reproducible anchor value for that. From it, target times per 100 m for endurance, threshold and speed sets can be derived.
| Zone | Pace relative to CSS | Typical use |
|---|---|---|
| Endurance | CSS + 6 to 10 s/100 m | long intervals, technique |
| Threshold | CSS ± 2 s/100 m | 100–400 m repeats |
| Speed | CSS − 3 to 6 s/100 m | short intervals with long rest |
The value remains a field value. Unlike metabolic diagnostics, there is no way to verify which energy provision actually sits behind it, which is why obseed treats CSS as a control metric and not as a physiological threshold.
How obseed measures it
Once CSS is known, you store it in obseed under body data in “performance values”:
To determine it, the following protocol can be swum. No special equipment is needed, only a stopwatch or swim watch.
| Set | Content | Purpose |
|---|---|---|
| 1 | 400 m easy | warm-up |
| 2 | 4 × 50 m drills, 20 s rest | activation |
| 3 | 4 × 100 m building, 20 s rest | pre-fatigue |
| 4 | 200 m easy | brief recovery |
| 5 | 4 × 50 m fast, 30 s rest | neuromuscular priming |
| 6 | 400 m maximal, evenly paced | test set |
| 7 | 200 m easy | cool-down |
Time, speed and heart rate from set 6 are entered under body data in “Swimming”. Recorded swim sessions are then evaluated against this value.
Example
An athlete swims the 400 m of set 6 in 6:40 min.
Distance: 400 m
Time: 400 s
CSS: 400 m / 400 s = 1.00 m/s
Pace: 1:40 min/100 mHer threshold sets therefore sit at 1:38 to 1:42 min/100 m, endurance intervals at around 1:46 to 1:50 min/100 m. If she improves the 400 m to 6:24 min after twelve weeks, CSS rises to 1.04 m/s and all zones shift by roughly 4 s per 100 m.
Categories
- Diagnostik
- Technische Begriffe