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

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 (CPx) 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, VO2max 68.6 mL·kg-1·min-1) and NA (n = 9, VO2max 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.

摘要 以通气阈（ventilatory threshold, VT）附近或恰好达到通气阈的强度进行训练，对久坐人群而言是提升其通气阈的有效刺激，但对于训练有素的人群则需要更高强度的运动刺激。心肺运动试验（cardiopulmonary exercise testing, CPx）的方案选择会影响通气阈的识别结果，进而降低运动处方制定的可靠性。本研究旨在验证：在优秀运动员（elite athletes, EA）与非运动员（non-athletes, NA）群体中，斜坡式递增负荷方案下测得的第一通气阈（VT1）与第二通气阈（VT2）对应的摄氧量（VO2）与心率（heart rate, HR），是否与同强度下恒负荷运动中测得的对应指标具有一致性。本研究共纳入18名健康受试者，分为两组：优秀运动员组（n=9，最大摄氧量VO2max为68.6 mL·kg⁻¹·min⁻¹）与非运动员组（n=9，VO2max为47.2 mL·kg⁻¹·min⁻¹）。所有受试者均完成心肺运动试验，并分别在48小时与96小时后，完成两项持续跑运动：一项为持续1小时的恒负荷跑（对应VT1强度），另一项为直至力竭的恒负荷跑（对应VT2强度）。研究结果显示：在VT1强度运动中，优秀运动员组的摄氧量差值占比为+9.1%（p=0.125），非运动员组则为+20.5%（p=0.012）。针对VT1的布兰德-奥特曼图（Bland-Altman plots）结果显示，优秀运动员组与非运动员组的偏倚分别为(4.4±6.9)与(5.5±5.6) mLO2·kg⁻¹·min⁻¹。在VT2场景下，非运动员组的摄氧量与心率偏倚分别为(0.4±2.9) mLO2·kg⁻¹·min⁻¹与(4.9±4.2) 次/分钟。本研究所采用的斜坡式递增负荷方案不适用于非运动员群体，因其会低估恒负荷运动中测得的VT1对应摄氧量与心率数值。而VT2场景下的心率指标与心肺运动试验结果一致性良好，可作为运动强度控制的有效参数。