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Hüseyin Akbulut, MSc (2026). Critical Swim Speed Test — Protocol, Norms and Application. Sporeus. Retrieved, October 7, 2026. https://sporeus.com/en/egzersiz-testleri-en/critical-swim-speed-test/
Updated: ·2 min read
Measures: Swimming endurance, critical swim speed (CSS), aerobic-threshold swim pace
Table of Contents
Difficulty: Orta | Category: Aerobik
Protocol
The Critical Swim Speed (CSS) Test, developed by Wakayoshi et al., is a field test protocol that estimates the swimmer’s maximum sustainable aerobic speed. CSS is an aquatic adaptation of the critical power concept. Preparation: The participant avoids intense exercise for 24 hours before the test. A 400–600m warm-up swim is performed. The participant prepares for two different maximal swim tests: these can be performed 24–48 hours apart, but ideally on the same day. Test Procedure: The test consists of two separate maximal sprints: 1. 400m maximal sprint: The participant swims 400 meters in the shortest possible time (T400). 2. 50m maximal sprint: After sufficient recovery, the participant swims 50 meters in the shortest possible time (T50). At least 30–45 minutes of recovery between the two tests is recommended. Data Recording: T400 (seconds) and T50 (seconds) are recorded. Calculation: CSS = (400 − 50) / (T400 − T50) = 350 / (T400 − T50) in meters per second. For example, if T400 = 400s and T50 = 40s, CSS = 350/360 ≈ 0.97 m/s. CSS Usage: CSS corresponds to the swimmer’s aerobic threshold speed and is used to determine training set durations and paces. Sets performed at 95–100% of CSS are planned as threshold training. Post-Test: The swimmer cools down with 200–400m at low tempo. CSS value is monitored throughout the season and training programs are updated accordingly.Formula
CSS (m/s) = (400 - 50) / (T400 - T50) = 350 / (T400_seconds - T50_seconds)
Equipment Required
25 m or 50 m pool, stopwatch, goggles and cap
Normative Values (Age: 18-25 (antrenöre yüzücüler))
| Classification | Male | Female |
|---|---|---|
| Excellent | CSS >1.45 m/s | CSS >1.30 m/s |
| Good | CSS 1.30-1.45 m/s | CSS 1.15-1.30 m/s |
| Average | CSS 1.10-1.30 m/s | CSS 0.95-1.15 m/s |
| Below Average | CSS 0.90-1.10 m/s | CSS 0.75-0.95 m/s |
| Poor | CSS <0.90 m/s | CSS <0.75 m/s |
Practical Applications
The CSS test is a fundamental tool for swimming coaches to individualize set intensities. It also provides critical data for pace planning in the triathlete swimming segment.Limitations
Covering two maximal sprints affects fatigue accumulation and standardization may be difficult in inexperienced swimmers. There is high dependence on technique.Related Tests: 12-Minute Swim Test, Tethered Swimming Sprint Test, FTP Test
Sources: Wakayoshi K et al., 1992, Eur J Appl Physiol; Toubekis AG & Tokmakidis SP, 2013, J Hum Kinet
References
- Wakayoshi K, Ikuta K, Yoshida T, Udo M, Moritani T, Mutoh Y, Miyashita M. (1992). Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer. European Journal of Applied Physiology and Occupational Physiology, 64(2): 153-157. doi:10.1007/BF00717953
- Toubekis AG, Tokmakidis SP. (2013). Metabolic responses at various intensities relative to critical swimming velocity. Journal of Strength and Conditioning Research, 27(6): 1731-1741. doi:10.1519/JSC.0b013e31828dde1e
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Hüseyin Akbulut is the founder of Sporeus and author of THRESHOLD (EŞİK), a 540-page Turkish-language book on endurance science.
- 540pp THRESHOLD Book
- MSc Sport Sciences
- Marmara University
Key Facts
Protocol The Critical Swim Speed (CSS) Test, developed by Wakayoshi et al., is a field test protocol that estimates the swimmer's maximum sustainable aerobic speed. CSS is an aquatic adaptation of the critical power concept. Preparation: The participant avoids intense exercise for 24 hours before the test. A 400–600m warm-up swim is performed. The participant prepares for two different maximal swim tests: these can be performed 24–48 hours apart, but ideally on the same day. Test Procedure: The test consists of two separate maximal sprints: 1. 400m maximal sprint: The participant swims 400 meters in the shortest possible time (T400). 2. 50m maximal sprint: After sufficient recovery, the participant swims 50 meters in the shortest possible time (T50). At least 30–45 minutes of recovery between the two tests is recommended. Data Recording: T400 (seconds) and T50 (seconds) are recorded. Calculation: CSS = (400 − 50) / (T400 − T50) = 350 / (T400 − T50) in meters per second. For example, if T400 = 400s and T50 = 40s, CSS = 350/360 ≈ 0.97 m/s. CSS Usage: CSS corresponds to the swimmer's aerobic threshold speed and is used to determine training set durations and paces. Sets performed at 95–100% of CSS are planned as threshold training. Post-Test: The swimmer cools down with 200–400m at low tempo. CSS value is monitored throughout the season and training programs are updated accordingly. Formula
CSS (m/s) = (400 - 50) / (T400 - T50) = 350 / (T400_seconds - T50_seconds)
Equipment Required
25 m or 50 m pool, stopwatch, goggles and cap
