Correlation properties of heart rate variability to assess the first ventilatory threshold and fatigue in runners

Bas Van Hooren; Bram Mennen; Thomas Gronwald; Bart C Bongers; Bruce Rogers

doi:10.1080/02640414.2023.2277034

Correlation properties of heart rate variability to assess the first ventilatory threshold and fatigue in runners

J Sports Sci. 2023 Nov 2:1-10. doi: 10.1080/02640414.2023.2277034. Online ahead of print.

Authors

Bas Van Hooren¹, Bram Mennen¹, Thomas Gronwald², Bart C Bongers^{1

3}, Bruce Rogers⁴

Affiliations

¹ Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands.
² MSH Medical School Hamburg, Institute of Interdisciplinary Exercise Science and Sports Medicine, Hamburg, Germany.
³ Department of Surgery, School of Nutrition and Translational Research in Metabolism (NUTRIM), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands.
⁴ College of Medicine, University of Central Florida, Orlando, Florida, USA.

PMID: 37916488
DOI: 10.1080/02640414.2023.2277034

Abstract

Purpose: The short-term scaling exponent alpha1 of detrended fluctuation analysis (DFA-a1) of heart rate variability (HRV) has shown potential to delineate the first ventilatory threshold (VT1). The aims of this study were to investigate the accuracy of this method for VT1 determination in runners using a consumer grade chest belt and to explore the effects of acute fatigue.

Methods: We compared oxygen uptake (V̇O₂) and heart rate (HR) at gas exchange VT1 to V̇O₂ and HR at a DFA-a1 value of 0.75. Gas exchange and HRV data were obtained from 14 individuals during a treadmill run involving two incremental ramps. Agreement was assessed using Bland-Altman analysis and linear regression.

Results: Bland-Altman analysis between gas exchange and HRV V̇O₂ and HR at VT1 during the first ramp showed a mean (95% limits of agreement) bias of -0.5 (-6.8 to 5.8) ml∙kg^-1∙min^-1, and -0.9 (-12.2 to 10.5) beats∙min^-1, with R² of 0.83 and 0.56, respectively. During the second ramp, the differences were -7.3 (-18.1 to 3.5) ml∙kg^-1∙min^-1 and -12.3 (-30.4 to 5.9) beats∙min^-1, with R² of 0.62 and 0.43, respectively.

Conclusion: A chest-belt derived DFA-a1 of 0.75 is closely related to gas exchange VT1, with the variability in accuracy at an individual level being similar to gas exchange methods. This suggests this to be a useful method for exercise intensity demarcation. The altered relationship during the second ramp indicates that DFA-a1 is only able to accurately demarcate exercise intensity thresholds in a non-fatigued state, but also opens opportunities for fatigue-based training prescription.

Keywords: DFA a1; HRV; Respiratory gas exchange; detrended fluctuation analysis; endurance exercise; fatigue.

Plain language summary

The first ventilatory threshold determined with a nonlinear method (DFA-a1) to analyse heart rate variability derived from a chest-belt shows close agreement to the gas exchange first ventilatory threshold, with the variability in accuracy at an individual level being similar to gas exchange methods. This suggests this to be a useful method for exercise intensity demarcation.The altered relationship during fatigue indicates that DFA-a1 is only able to accurately demarcate exercise intensity thresholds in a non-fatigued state, but this also opens opportunities for fatigue-based training prescription.