DFAα1-derived heart rate variability thresholds showed moderate-to-high agreement with ventilatory thresholds (ICC > 0.60) and retained sensitivity across exercise intensity domains.
Cross-Sectional (n=27)
Does DFAα1 accurately estimate ventilatory thresholds and monitor exercise intensity in healthy young adults compared to standard criteria and linear HRV parameters?
DFAα1 is a promising intensity-sensitive biomarker for individualized exercise prescription, though individual variability limits its use for precise threshold estimation.
Effect estimate: ICC > 0.60
BACKGROUND: While heart rate variability (HRV) offers a non-invasive alternative for ventilatory thresholds (VTs) estimation, its conventional linear parameters (e.g., RMSSD) exhibit a "floor effect" limiting utility. DFAα1 is a promising non-linear HRV parameter, reflecting the complex pattern of autonomic regulation. This study evaluated DFAα1 for threshold estimation, intensity monitoring, and recovery assessment. METHODS: 27 healthy adults underwent an incremental cycle ergometer test. VTs were determined via standard criteria, while HRV thresholds (HRVTs) were determined using multiple parameters. A subset (n = 19) then performed low to severe intensity exercise tests (E1-E4) to validate HRV sensitivity and dynamic responses. RESULTS: For HRVT1 vs. VT1: DFAα1-derived HRVT1 exhibited the highest ICC (> 0.60) among all parameters but with a systematic bias; for HRVT2 vs. VT2: DFAα1-derived HRVT2 exhibited moderate-to-high ICC (> 0.60) and RMSSD-derived achieved the highest ICC (0.88-0.95). During E1-E4, DFAα1 and the natural log of RMSSD (LnRMSSD) both decreased during exercise and increased during recovery. During exercise, DFAα1 in E1 and E2 exceeded in E3 and E4, while LnRMSSD was higher in E1 than in E2-E4 (all P < 0.05). During recovery in E2-E4, DFAα1 exceeded baseline, and this rebound was delayed with intensity, while LnRMSSD was lower than baseline with a downward trend. CONCLUSIONS: DFAα1 showed potential for estimating both VTs, retained sensitivity across intensity domains, and showed recovery dynamics proportional to prior intensity. Despite individual variability suggesting use for broad zoning rather than precise estimation, DFAα1 serves as an intensity-sensitive biomarker for individualized exercise prescription.
Deng et al. (2026) conducted a cross-sectional in Healthy young adults (n=27). DFAα1 (non-linear HRV parameter) vs. RMSSD and ventilatory thresholds (VTs) was evaluated on Agreement between DFAα1-derived HRV thresholds and ventilatory thresholds (VTs) (ICC > 0.60). DFAα1-derived heart rate variability thresholds showed moderate-to-high agreement with ventilatory thresholds (ICC > 0.60) and retained sensitivity across exercise intensity domains.