DETERMINATION AND VALIDITY OF CRITICAL VELOCITY AS AN INDEX OF SWIMMING PERFORMANCE IN THE COMPETITIVE SWIMMER

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 (upsilon(crit)). The upsilon(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 upsilon(crit) at those velocities until the onset of fatigue. A regression analysis of d(lim) on t(lim) calculated for each swimmer showed linear relationships (r2 > 0.998, P < 0.01), and the slope coefficient signifying upsilon(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 (VO(2max)), oxygen consumption (VO2) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (upsilon(OBLA)) were also determined during the incremental swimming test. The upsilon(crit) showed significant positive correlations with VO2 at anaerobic threshold (r = 0.818, P < 0.01), upsilon(OBLA) (r = 0.949, P < 0.01) and mean velocity of 400 m freestyle (r = 0.864, P < 0.01). These data suggested that upsilon(crit) could be adopted as an index of endurance performance in competitive swimmers.