Resumen de Reprodutibilidade das variaveis derivadas da curva de freqüência cardíaca em teste progressivo
Fernando Roberto de Oliveira, Poliana dos Santos Piovezana
The linear adjustment of the heart rate (HR) curve in progressive tests is the most frequently used in the assessment and prescription of exercises, in spite of the several non-linear behavior evidences, such as the establishment of the HR deflection point (HRDP) (Conconi et al., 1982). Lima (1997) showed that the sigmoid adjustment is higher than the linear one in the HR-load ratio representation, following the identification of the intensity of the maximum acceleration curve named 'heart rate inflection point' (HRIP). However, the need to establish the reproducibility of such findings still remains. Objective: To compare the limiar adjustment to the sigmoidone; and to establish the consistency of the HR, HRIP, and HRDP identified in a cycle-ergometer. Eleven healthy individuals (27,5 ± 9,9 years; 74,3 ± 10,2 kg; 178,5 ± 7,9 cm; 10,7 ± 5,2 %G) undertook two progressive tests (T1 e T2), being the initial load 50W, incremented by 15w after every minute. The HR was measured on a Polar® monitor (model S610) and the adjustments of individual curves were made by using the GraphPad Prism Software, version 1.03 (1994 - Graphpad Software Incorporated®), this linear model was compared to the Boltzmann sigmoid. The HRDP was identified by means of Dmax (Kara et al., 1996). Variables identified: maximum power (Pmax), HRmax, power in the HRDP, and power in the HRIP. The comparison of the tests results was carried out starting from the analysis of the intraclass correlation factor. Results:
*P<0,05 The sigmoid adjustment was significantly higher to the linear one in 90,9% (10 individuals) and 72% (eight individuals) who were assessed in the 1st and 2nd tests, respectively. On the other individuals, the difference was not significant. The HRIP was identified in T1= 81,8% (nine individuals) and T2= 72,7% (eight individuals) of those who were assessed. The HRDP, as expected, was identified in all the tests, however, opposed to the previous expectation, a similar intensity to the HRIP was found (P>0,05). Conclusions: Evidences of the reproducibility of variables and curve adjustments of the HR identified in a progressive test in a cycle-ergometer, by applying this methodology, the HRIP and the HRDP, seen to be within the same physiological domain.
