Oxygen consumption and heart rate obtained in a ramp protocol are equivalent during exercise session of rectangular loading at ventilatory thresholds for athletes

Consumo de oxigênio e frequência cardíaca obtidos em um protocolo de rampa são equivalentes durante sessão de exercícios de carga retangular nos limiares ventilatórios para atletas

Abstract

Training near or at ventilatory threshold (VT) is an adequate stimulus to improve the thresholds for sedentary subjects, but a higher intensity is necessary for conditioned subjects. The choice of cardiopulmonary exercise testing (CP_x) protocol has an influence on VTs identification and can reduce their reliability for exercise prescription. This study tested if VO₂ and heart rate (HR) corresponding to first (VT1) and second ventilatory threshold (VT2) determined during a ramp protocol were equivalent to those observed in rectangular load exercises at the same intensity in runners elite athletes (EA) and non-athletes (NA). Eighteen health subjects were divided into two groups: EA (n = 9, VO_2max 68.6 mL·kg^-1·min^-1) and NA (n = 9, VO_2max 47.2 mL·kg^-1·min^-1). They performed CPx and 48h and 96h later, a continuous running lasting 1 h for VT1 and until exhaustion for VT2. The results showed that EA at VT1 session, presented delta differences for VO₂ (+9.1%, p = 0.125) vs. NA (+20.5%, p = 0.012). The Bland-Altman plots for VT1 presented biases of (4.4 ± 6.9) and (5.5 ± 5.6 mLO₂·kg^-1·min^-1) for AE and NA, respectively. In VT2, the VO₂ and HR of the NA showed biases of (0.4 ± 2.9 mLO₂·kg^-1·min^-1) and (4.9 ± 4.2 bpm). The ramp protocol used in this study was inappropriate for NA because it underestimates the values of VO₂ and HR at VT1 found in the rectangular load exercise. The HR showed good agreement at VT2 with CPx and may be a good parameter for controlling exercise intensity.

Key words
Exercise testing; Continuous running; Training prescription; Runners; Elite athletes