Validade do limiar de variabilidade da frequência cardíaca (DFA α1) para estimar a velocidade crítica

Abstract

Introduction: Short-term trend-adjusted fluctuation analysis (DFA α1) is a recent metric in the field of sports, with the potential to identify exercise intensity thresholds in a single visit. A widely used test in this context is the critical speed (CS) test, although its application requires at least two days to complete. Validating the thresholds of both methodologies is very important for optimizing aerobic training prescription. Objectives: 1) To systematically review the literature on the applicability of DFA α1 in identifying intensity thresholds, comparing it with traditional methods, 2) To evaluate the agreement between the speeds obtained using DFA α1 0.5 and CS in runners. Methodology: In study 1, using the PRISMA methodology and searching five databases, a systematic review was conducted. In study 2, the sample consisted of 16 male runners (26.1 ± 7.6 years; BMI: 22.9 ± 1.7), who participated in three visits to the Faculty of Physical Education and Sports at UFJF to perform tests on a treadmill and on the athletics track. Results: The systematic review totaled 19 articles and found a lack of studies involving female samples and a need for standardization of protocols for better agreement between measurements. In study 2, there was no significant difference between speeds (p = 0.140). The average speed of DFA α1 0.5 was 15.3 ± 1.6 km/h, while that of VC was 15.8 ± 1.7 km/h. The Bland-Altman plot showed a mean difference of -0.5 km/h. Conclusion: Further investigation of DFA α1 is needed to identify the first intensity threshold, and protocols need to be standardized for both thresholds. Regarding the agreement between VC and DFA α1 speeds in the treadmill stress test, there was no significant difference between them, and moderate agreement was found (r: 0.735). Therefore, the use of this methodology is recommended for trained runners.