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

Summary

The purpose of this investigation was to test whether the concept of critical power used in previous studies could be applied to the field of competitive swimming as critical swimming velocity (ν_crit). The ν_crit, defined as the swimming velocity over a very long period of time without exhaustion, was expressed as the slope of a straight line between swimming distance (d _lim) at each speed (with six predetermined speeds) and the duration (t _lim). Nine trained college swimmers underwent tests in a swimming flume to measure ν_crit at those velocities until the onset of fatigue. A regression analysis ofd _lim on trim calculated for each swimmer showed linear relationships (r ²>0.998,P<0.01), and the slope coefficient signifying ν_crit ranged from 1.062 to 1.262 m · s⁻¹ with a mean of 1.166 (SD 0.052) m · s⁻¹. Maximal oxygen consumption ($\dot VO_{2\max }$), oxygen consumption ($\dot VO_2$) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (ν_OBLA) were also determined during the incremental swimming test. The ν_crit showed significant positive correlations with$\dot VO_2$ at anaerobic threshold (r=0.818,P<0.01), ν_OBLA (r=0.949,P<0.01) and mean velocity of 400m freestyle (r=0.864,P<0.01). These data suggested that ν_crit could be adopted as an index of endurance performance in competitive swimmers.