Critical swimming speed test

Critical swimming speed (CSS) tests were developed by Wakayoshi and his associates to estimate the threshold pace for endurance training. The defined the critical swimming speed as the fastest speed swimmers could maintain continuously without exhaustion. Therefore, they believe that it represents an athlete’s maximal lactate steady state.

The procedure of determining the critical swimming speed involves swimming a minimum of two time trials from a push off, although three or more trials are recommended. Any combination of the following time trial distances have been recommended for this purpose: 50, 100, 200, and 400m. When only two time trials are used, the distances should be considerably different. There should be at least a 30 minute rest between swims. It is also recommended that the swims should be performed over a 2 or 3 days period, especially when the 3 or 4 time trials are used.

A simple procedure to calculate the critical swimming speed (the other involves a graphic representation of the calculation of a regression line from the results of the time trials) from two time trials is to use the following equation:

v_crit = (d₂ – d₁)/ (t₂ – t₁) 

CSS = 100 ÷ v_crit 

Where d₂ = longer distance, d₁ = shorter distance, t₂ = time for longer distance, t₁ = time for shorter distance 

When calculating critical swimming speed you may want to avoid using shorter repeat distances, like the 50s and 100s as they tend to overestimate critical swimming speed.

Once calculated, the critical swimming speed can be used to prescribe swimming times for repeats sets at threshold pace. For basic endurance training times should be adjusted upward by 3 to 6 seconds per 100m, and for overload endurance training times should be faster than the critical swimming speed. Maglischo suggests that the critical swimming speed overestimates individual anaerobic threshold pace, therefore, the speed of the training repeats should be 2 to 3 seconds slower per 100m than the actual critical swimming speed.

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