Heart rate variability-derived thresholds (SD1 and RMSSD) showed significant agreement and large paired-sample correlations with absolute power outputs at ventilatory threshold 1.
Observational (n=21)
Do HRV-established thresholds accurately estimate ventilatory and lactate thresholds in endurance athletes?
HRV parameters SD1 and RMSSD can be used to determine VT1-related training workloads in endurance athletes, providing a non-invasive alternative when laboratory testing is unavailable.
This study aimed to determine the use of heart rate variability (HRV)-established thresholds to accurately estimate endurance athletes' ventilatory threshold 1 (VT1), respiratory compensation point (RCP) and lactate threshold 2 (LT2). Eleven cyclists (aged: 23.7 ± 3.1 years) from the African Continental Development Cycling team and ten middle- and long-distance athletes (age: 21.2 ± 1.8 years) from a South African university participated in this study. Before the start of an incremental cycling or running maximal oxygen consumption (V̇O2max) test each participant was fitted with a Fixed Polar HR Transmitter Belt and Monitor to determine the R-R intervals of the last 60 seconds of each stage. The Kubios HRV Premium software package was used to analyze the R-R-intervals. Blood samples were taken 30 seconds before the end of each stage and analyzed for blood lactate. Ventilatory threshold points were identified using the criteria of an increase in V̇E/V̇O2 with no increase in V̇E/V̇CO2 (VT1) and an increase in both V̇E/V̇O2 and V̇E/V̇CO2 (RCP). The LT2 was identified as the second increase in blood lactate concentration from one increment to the next. Concerning HRV thresholds, VT1 was determined at a DFAα1 value of 0.75, the first breakpoint in the standard deviation of the instantaneous (SD1) and continuous long-term RR interval (SD2) curves, the visual deflection in the squared root of the mean squared differences between successive R-R intervals (RMSSD) curve, and the first abrupt increase in high-frequency (HF) power x HF frequency. The RCP was detected at a DFAα1 value of 0.5 and the final abrupt increase in HF. The Bland-Altman plots revealed that the absolute power outputs at VT1SD1 and VT1RMSSD showed significant agreements with the absolute power outputs at VT1. Large paired-sample correlations were also found between the absolute power outputs at VT1SD1, VT1RMSSD and VT1. In conclusion, coaches, sport scientists and other professionals are encouraged to use SD1 and RMSSD to determine the VT1-related training program workloads of endurance-trained athletes, especially in areas where laboratories are not available.
Thiart et al. (Sat,) conducted a observational in Endurance athletes (n=21). Heart rate variability (HRV)-established thresholds vs. Ventilatory and lactate thresholds was evaluated on Agreement between absolute power outputs at HRV thresholds and ventilatory/lactate thresholds. Heart rate variability-derived thresholds (SD1 and RMSSD) showed significant agreement and large paired-sample correlations with absolute power outputs at ventilatory threshold 1.