Correlation between critical force and critical velocity and their respective stroke rates

Abstract

The critical power model has been utilized to estimate the anaerobic and aerobic capacities in swimming. There are studies which evidence the applicability of swimming velocity, force during tethered swimming and stroke rate data to the critical power model. However, the relationship among these estimates derived from freestyle and tethered swimming needs to be established. Therefore, the aim of this study was to evaluate the relationship between critical force (FCRIT) obtained from tethered swimming and critical velocity (VCRIT) during freestyle swimming (VCRIT), and their respective critical stroke rates (FBrCRIT). Eleven swimmers of both sexes (16.6 ± 1.3 years, 60 ± 10 kg, 172 ± 8 cm) underwent maximal tests to exhaustion in the tethered system and to as fast as possible trials during 200 and 400 m freestyle swimming. There were estimates of: 1) FCRIT and CIAnaer fi tting the three known equations derived from the critical power model (hyperbolic forcetime F-t, linear force-1/time F-1/t, linear impulse-time I-t); 2) VCRIT and CNAnaer during the freestyle tests using the linear distance-time relationship (d-t) and; 3) FBrCRIT and CBrAnaer during both kinds of tests (tethered and freestyle). The tethered performance data presented a good fi tting to the critical power model: FCRIT (R2 of 0.98, 0.97 and 0.99) and FBrCRIT-TETHERED (R2 of 0.96, 0.90 and 0.99). There was a high correlation between VCRIT and FCRIT (r= 0.89-0.91). Nevertheless, there was no signifi cant correlation among the estimates of FBrCRIT-TETHERED and FBrCRIT-FREESTYLE, neither among the anaerobic variables. These results indicate that FCRIT can be considered a reliable aerobic capacity index. However, the FBrCRIT-TETHERED did not approach this capacity, despite the good fi tting to the critical power model.