Relationship Between Heart Rate Variability Threshold and 5-km Outdoor Running Performance in Non-athletes

Abstract

The analyses of heart rate variability threshold (HRVT) under a controlled treadmill incremental exercise test (IET) is considered a practical strategy for cardiac parasympathetic depression and anaerobic threshold assessment. However, the prognostic value of HRVT for outdoor running performance is unknown. PURPOSE: To correlate the exercise intensity at the HRVT assessed during a treadmill incremental test and the 5-km outdoor running time in young men. METHODS: 14 beginner runners (23.5±4.4 yrs, BMI: 23.2±2.7 kg/m2) underwent a treadmill IET. The R-R intervals were collected continuously during exercise test using a heart rate monitor (Polar® v800) and heart rate variability was analyzed by the SD1 index of Poincaré Scatterplot map. HRVT was considered the load (km/h) corresponding to the point of stabilization at which there was no further significant decline in the values of the SD1 index even with increasing intensity. After a 48h period, the participants individually performed a 5-km running trial on an outdoor 250-m track. The participants were encouraged to conclude the 5-km running test as quickly as possible. Due to non-normality of the data and the sample size, we used the Spearman’s correlation test with p-value set at 5%. RESULTS: The exercise intensity at HRVT was 7 (7-8) km/h and the time to complete the 5-km trial was 25.2 (23.2-28.5) minutes. A strong correlation was observed between the treadmill speed at the HRVT and the time expended to cover the 5-km running test (Figure 1). CONCLUSION: HRVT evaluated during an IET under controlled conditions was negatively correlated with the outdoor 5-km running performance in young non-athlete men. Our results may open a new application to the HRVt as a practical tool for the prognostic evaluation of a 5-km running performance.Figure 1: Relationship between HRVT and 5-km time trial.