Determination of heart rate threshold from heart rate kinetics during maximal graded exercise in soccer players

Paulo Farinatti,Silvio Rodrigues Marques Neto,Viviane Faleiro,Alexandre Gurgel,Eduardo Lattari,Geraldo Maranhão Neto,Sérgio Machado

doi:10.1590/1980-0037.2019v21e57829

Abstract

Abstract The main of the present study was to identify the heart rate threshold based on heart rate kinetics during graded maximal exercise in football players. Twenty-six male football players performed a maximal exercise test (Bruce protocol) on a motor-driven treadmill. Oxygen uptake (VO2) and heart rate (HR) were monitored, recorded and resampled at 3.5Hz. The ventilatory threshold (VT), and respiratory compensation (RC), heart rate deflection points (HRDP1 and HRDP2) and heart rate kinetics threshold (HRT) were determined by computerized methods. The heart rate variability (HRV) was assessed in the frequency domain. The HRT averaged 89.9 ± 1.2 % of the VO2 peak. The HRT showed poor correlations and significant differences compared with HRDP1 (r = 0.46) and VT (r = 0.51), but was not different from, and highly correlated with, HRDP2 (0.98) and RC (0.90). Bland Altman plots showed all athletes into 95% of limits of agreement, and intraclass correlation coefficient showed good agreements between points obtained from HRT compared with HRDP2 (0.96) and RC (0.98). The HRT was highly correlated with HRDP2 and RC, suggesting it could be a marker for cardiorespiratory fatigue.

Highlights

Since the classical studies by Wassermans group, determination of both anaerobic threshold (AT) and peak oxygen uptake (VO2 peak) have been shown to reflect crucial aspects of cardiorespiratory capacity and have been used to determine the exercise intensity within aerobic training[1,2]
The major findings of this study are that HR threshold (HRT) presented weak correlations with both HRDP1 and ventilatory threshold (VT), but strong correlations with HRDP2 and respiratory compensation (RC)
The present results show that the point in which heart rate (HR) kinetics stopped presenting steady-state coincided with the second deflection in HR (HRDP2), which is related to a decrease in HR kinetics amplitude as well as to RC

Summary

Introduction

Since the classical studies by Wassermans group, determination of both anaerobic threshold (AT) and peak oxygen uptake (VO2 peak) have been shown to reflect crucial aspects of cardiorespiratory capacity and have been used to determine the exercise intensity within aerobic training[1,2]. During continuous exercise, oxygen kinetics might present different response patterns depending on the nature of metabolic demands. In exercises performed below AT, oxygen uptake increases initially as a monoexponential function, followed by a plateau phase of approximately 2-3 min (steady state). In exercises performed above AT, a triexponential model seems to be more accurate to describe the oxygen kinetics. A slow rise in oxygen uptake (VO2) on the primary component is observed and a steady state phase is less likely to occur[3]

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Conclusion