REF-874 · Wakayoshi et al., 1992 · European Journal of Applied Physiology and Occupational Physiology, Vol. · Paper · PubMed

Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

The authors asked whether the critical power concept applies to competitive swimming as a critical swimming velocity (vcrit), the speed that can in theory be held for a very long time without exhaustion. Nine trained college swimmers swam to fatigue at six predetermined speeds in a swimming flume; distance was plotted against time, and the slope of the line was vcrit.

The relationship was almost perfectly linear, and vcrit correlated with VO2 at the anaerobic threshold, with the speed at the onset of blood lactate accumulation and with 400-m freestyle speed. The authors conclude that vcrit can be used as an index of endurance performance in competitive swimmers.

Participants

n=9 trained college swimmers (abstract: "Nine trained college swimmers"); MEDLINE indexing lists male participants, adolescent and adult.

Protocol

Swims to fatigue in a swimming flume at six predetermined speeds; distance (dlim) regressed on duration (tlim) for each swimmer; the slope = vcrit.
Incremental swimming test for VO2max, VO2 at the anaerobic threshold and the velocity at the onset of blood lactate accumulation (vOBLA).
vcrit compared with those markers and with mean velocity of a 400-m freestyle.

Key Results

Distance-time relationship linear for every swimmer: r2 greater than 0.998 (P less than 0.01).
vcrit ranged from 1.062 to 1.262 m.s-1, mean 1.166 (SD 0.052) m.s-1.
vcrit correlated withrP
VO2 at anaerobic threshold0.818less than 0.01
vOBLA0.949less than 0.01
Mean velocity of 400 m freestyle0.864less than 0.01

Practical Application

In nine trained college swimmers tested in a flume, the critical swimming velocity from a distance-time line (mean 1.166 m.s-1) correlated closely with the speed at the onset of blood lactate accumulation (r = 0.949) and with 400-m freestyle speed (r = 0.864). To "is CSS a real threshold or just a pool-deck formula?": the idea behind it — a swimming speed you can sustain for a long time, taken from how far you can swim over different durations — was validated against lactate and aerobic markers in this founding study.
Use CSS as the anchor for swim zones and swim load in the same way critical power anchors cycling and critical speed anchors running.
Inference, not tested here: today's common pool version uses two time trials over different distances; this study used six flume speeds, so the two-trial shortcut rests on the same concept but was not what was tested.
Not from this paper; the base's own practice: the sprint and Olympic triathlon framework SYNTH-52 uses CSS for swim pacing and zones.

Limitations

Nine male college swimmers; flume swimming, not a pool.
Six fixed-speed trials to fatigue per swimmer — a lab protocol much heavier than the field versions used today.
Correlations with 400-m speed show ranking agreement, not that vcrit can be held for any stated duration.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

test validation study, n=9