Estimation of the intensity of physical activity (PA) based on absolute accelerometer cut points (Cp) likely over- or underestimates intensity for a specific individual. The purpose of this study was to investigate the relationship between absolute moderate intensity Cp and the first ventilatory threshold (VT₁). A group of 24 pregnant and 15 nonpregnant women who performed a submaximal incremental walking test with measures of ventilatory parameters and accelerations from three different accelerometers on the wrist (ActiGraph wGT3X-BT, GENEActiv, Axivity AX3) and one on the hip (Actigraph wGT3X-BT) were analyzed. Cp were determined corresponding to 3 metabolic equivalents of task (MET), using the conventional MET definition (Cp_3.5) (3.5 mL/kg×min) and individual resting metabolic rate (Cp_ind). The ventilatory equivalent (VE/VO₂) was used to determine VT₁. Accelerations at VT₁ were significantly higher (p < 0.01) compared to Cp_3.5 and Cp_ind in both groups. Cp_3.5 and Cp_ind were significantly different in nonpregnant (p < 0.01) but not in pregnant women. Walking speed at VT₁ (5.7 ± 0.5/6.2 ± 0.8 km/h) was significantly lower (p < 0.01) in pregnant compared to nonpregnant women and correspondent to 3.8 ± 0.7/4.9 ± 1.4 conventional METs. Intensity at absolute Cp was lower compared to the intensity at VT₁ independent of the device or placement in pregnant and nonpregnant women. Therefore, we recommend individually tailored cut points such as the VT₁ to better assess the effect of the intensity of PA.

中文翻译：

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基于绝对加速度计的强度处方与孕妇和非孕妇的生理变量相比。

根据绝对加速度计切割点（Cp）估算身体活动强度（PA）可能会高估或低估特定个体的强度。这项研究的目的是调查绝对中等强度Cp与第一通气阈值（VT ₁）之间的关系。一组24名孕妇和15名非孕妇，通过手腕上的三种不同加速度计（ActiGraph wGT3X-BT，GENEActiv，Axivity AX3）和一名髋部（Actigraph wGT3X- BT）进行了分析。使用常规MET定义确定对应于3个代谢当量任务（MET）的Cp（Cp _3.5）（3.5 mL / kg×min）和个体静息代谢率（Cp _ind）。通气当量（VE / VO ₂）用于确定VT ₁。与两组中的Cp _3.5和Cp _ind相比，VT _1的加速度显着更高（p <0.01）。非孕妇的Cp _3.5和Cp _ind显着不同（p <0.01），但孕妇没有差异。VT _1时的步行速度（5.7±0.5 / 6.2±0.8 km / h）明显较低（p与未怀孕妇女相比，孕妇<0.01）与传统MET的3.8±0.7 / 4.9±1.4相对应。与VT ₁强度相比，绝对Cp强度要低，与孕妇和未怀孕妇女的装置或放置无关。因此，我们建议单独定制切点，例如VT _1，以更好地评估PA强度的效果。