Approximation of Critical Speed Based on Critical Stroke Rate in Competitive Front-Crawl Swimming

Abstract

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 non-linear 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 (CSR) relationship to approximate a swimmer's CS. PURPOSE: To determine whether the CSR relationship can be used to accurately predict CS in competitive front-crawl swimming. METHODS: Eight elite competitive swimmers (6 female, 2 male; 17.9 ± 0.86 yrs) performed three timed maximal effort swims (200 m, 400 m and 1000 m front crawl) to determine CS. The participants then completed a 4 × 200 m interval training set (60 s rest) at progressively increasing exercise intensities, with the 3rd 200 performed at CS: 1) LT1 = 91% of CS; 2) MLSS = 96.5% of CS; 3) 100% of CS and 4) VO2 Max. = 110% of CS. SR was recorded for each 25 m length of each 200 m repetition and CSR was calculated based on the relationship CSR = SR min.* 1.23. A paired Student's t-test compared mean CS to the 3rd 200 speed and the predicted CSR to the actual 3rd 200 SR to demonstrate there were no differences between the compared variables. A Pearson r correlation statistic was also used to quantify the relationship between the predicted CSR and the 3rd 200 SR. RESULTS: No differences were found between mean CS and the 3rd 200 speed (p > 0.35), indicating that the participants successfully performed the 3rd 200 m repetition at CS (the mean difference between the two parameters was 0.03 m·s-1). There were also no differences between the predicted CSR and the actual 3rd 200 SR (p > 0.65). Most importantly, the mean difference between the predicted CSR and the 3rd 200 SR (i.e., the SR at CS) was 0.07 cycles·min-1 or 0.18%. Further, the predicted CSR was highly correlated with the actual SR recorded during the 3rd/CS 200 (r = 0.99). CONCLUSION: The findings demonstrate that predicted CSR values (based on a participant's baseline SR) are consistent with the actual SR's used by participants when swimming at CS. As such, the results show that the CSR relationship can be used to accurately approximate CS in elite competitive front-crawl swimming.