Barden, J. M., Kell, R. T., & Kobsar, D. (2011). Approximation of critical speed based on critical stroke rate in competitive front-crawl swimming. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 2322.

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"In front-crawl swimming, it has been shown that the point at which a non-linear increase in stroke rate (SR) occurs is consistent with a swimmer's critical speed (CS). This nonlinear change in SR is known as the critical stroke rate (CSR), and can be predicted based on a swimmer's baseline SR (defined as the minimum SR that occurs at low-intensity exercise). Consequently, if the baseline SR is known, it is theoretically possible to use the critical stroke rate relationship to approximate a swimmer's critical speed."

This study determined if the critical stroke rate relationship can be used to accurately predict critical speed in competitive front-crawl swimming. Elite competitive swimmers (M = 2; F = 6) performed three timed maximal effort swims (200, 400, and 1000 m front crawl) to determine critical speed. Ss then completed a 4 x 200 m interval training set (60 s rest) at progressively increasing exercise intensities. The intensities were 1) lactate threshold = 91% of CS; 2) maximum lactate steady state = 96.5% of CS; 3) 100% of CS; and 4) VO2max = 110% of CS. Stroke rate was recorded for each 25 m length of each 200 m repetition and critical stroke rate was calculated based on the relationship CSR = SR min.* 1.23.

No differences were found between mean critical speed and the third 200 speed, indicating that Ss successfully performed the third 200 m repetition at critical speed. There were also no differences between the predicted critical stroke rate and the actual third 200 stroke rate both of which were very highly correlated.

Implication. Predicted critical stroke rate values (based on a participant's baseline stroke rate) are consistent with the actual stroke rates used by swimmers when swimming at critical speed. As such, the results show that the critical stroke rate relationship can be used to accurately approximate critical speed in elite competitive front-crawl swimming. What the value of critical speed swimming is, since it does not replicate a swimming velocity that is likely in a pool competitive event, has yet to be determined.

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