HEART RATE DEFLECTION, HEART RATE TURN POINT, AND MAXLASS IN DIFFERENT INCREMENTAL EXERCISE TESTS

Abstract

PURPOSE: The aim of this investigation was to determine reproducible and valid measures of the direction and degree of deflection of the heart rate performance curve (HRPC), and the heart rate turn point (HRT) in patients with documented cardiovascular disease (CVD) and in healthy subjects. METHODS: 28 subjects performed an incremental cycle ergometer test [T1; 25 watts (W) every 2 min], an individual test (T2), adjusted to the predicted maximal power output with either 5, 7.5, 10 or 15 W increments every min and exercise tests with constant workloads lasting 30 min to define metabolic and respiratory steady state intensities (STST). The degree and direction of the deflection of HRPC were described as factor k (k > 0.1: downward deflection; −0.1 < k < 0.1: linear time curse; k < −0.1: upward deflection). HRTP was assessed by linear turn point analysis. We used respiratory gas exchange measures and lactate concentrations for determination of STST conditions. RESULTS: The deflection of the HRPC was reproducible yielding and r = 0.689; p < 0.001 in both incremental tests. The correlation between the power output at maximal STST and the power output at the HRTP in the individual test resulted in r = 0.942, (p < 0.001). Compared to the T1, the correlation yielded an r = 0.799, (p < 0.001). However, using the z-transformation, the correlation at individual tests (T2) showed significantly better results (p < 0.05) in contrast to T1. CONCLUSION: Although the direction and degree of the HRPC is reproducible in both incremental tests, the individual protocol is more suitable to predict maximal respiratory and metabolic steady state intensities. We therefore recommend the use of individual tests for both performance diagnostics and training purposes in healthy subjects and in patients with CVD.