Toubekis, A. G., Tsami, A. P., Smilios, I. G., Douda, H. T., & Tokmakidis, S. P. (2011). Training-induced changes on blood lactate profile and critical velocity in young swimmers. Journal of Strength and Conditioning Research, 25, 153-157.

This study examined the efficacy of critical swimming velocity for training prescription and monitoring the changes induced on aerobic endurance after a period of increased training volume and intensity in young swimmers. An experimental group (N = 7; ~13.3 years) was tested (critical velocity, lactate threshold], velocity corresponding to a blood lactate concentration of 4 mmol) at the beginning and after six and fourteen weeks of training. A control group (N = 7; ~14.1 years) did not train and was used to observe maturation effects as well as being tested for critical velocity changes between weeks 0 and 14. The average weekly training volume was increased after the sixth week in the experimental group.

Training pace adjusted according to the critical velocity pace improved the lactate threshold velocity and velocity at 4 mmol lactate concentration in young swimmers after 6 and 14 weeks of training, respectively. However, critical velocity did not change during the same training period in response to a non-changing stimulus. The aerobic endurance indexes measured in this study (critical velocity, lactate threshold, and velocity at 4 mmol lactate) did not follow the same rate of change during the training period. A 15% increase in mean weekly training volume for a period of eight weeks did not induce any further improvements in critical velocity, lactate threshold, or velocity at 4 mmol lactate.

Implication. Critical velocity swimming is at best a weak factor for indicating aerobic adaptation in young swimmers. Aerobic indexes change at different rates when imbedded in the same program. Therefore, critical velocity, lactate threshold, and velocity at 4 mmol lactate cannot be used interchangeably and are not related in young swimmers.

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