Critical load forced-swim test with Wistar rats does not properly estimate anaerobic threshold: The relationship with morphophysiological factors and performance indices

Abstract

Summary Objective The study aimed to correlate morphophysiological characteristics associated with performance and indices associated with the critical power model, and to verify the time to exhaustion (Tlim) at critical load (CL) intensity. Methods Twenty male Wistar rats were submitted to four predictive tests to determine CL and anaerobic swim capacity (ASC) intensity using hyperbolic and Busso's models. Subsequently, they were submitted to exercise at 100% of CL intensity derived from hyperbolic model until exhaustion, and the time was recorded to the nearest second. The day after, animals were euthanized for blood and tissue collection. Results Significant relationships were found among the indices CL, ASC (derived from the both models) and Tlim (P 0.05). Conclusion We can conclude that the CL rat swimming model does not properly estimate the anaerobic threshold intensity. Furthermore, the correlations with morphophysiological variables indicate that none of variables alone can account for performance at CL intensity.