Department of Kinesiology, Samford University, Lakeshore, AL 35229, USA.
Int J Environ Res Public Health. 2021 Jun 19;18(12):6593. doi: 10.3390/ijerph18126593.
Evidence has established that a cadence of 100 steps/min is indicative of the moderate intensity threshold of 3 metabolic equivalents (METs), but this has only been described in non-pregnant individuals. As metabolic alterations are well established during pregnancy, the purpose of this study was to determine if the walking cadence equivalent to 3 METs in pregnant women is similar to non-pregnant populations. Pregnant females ( = 29; age = 30.3 ± 3.2 years, gestational age = 23.9 ± 6.6 weeks) in their second or third trimester (>12 weeks gestation) completed three stages of treadmill walking for 5 min at different standardized walking speeds: 2.5, 3.0, and 3.5 miles per hour (mph). Oxygen consumption (VO2) and heart rate (HR) were measured each minute and METs were calculated for each stage. Real-time continuous monitoring of walking cadence was evaluated by an OptoGait gait analysis system. Following the three standardized speed stages, participants completed an additional stage walking at a speed that elicited 100 steps/min; VO2 and HR were also collected. A one-sample t-test was used to compare MET values at each stage to the heuristic 3 MET cutoff, and Pearson correlation coefficient was calculated to evaluate the relationship between cadence and METs. Mean cadence increased linearly across the three stages (2.5 mph = 103.7 ± 4.5, 3.0 mph = 112.5 ± 5.3, and 3.5 mph = 120.4 ± 6.2 steps/min), as did METs (2.5 mph = 2.7 ± 1.7, 3.0 mph = 3.2 ± 0.8, and 3.5 mph = 4.3 ± 1.8 METs) regardless of trimester. The average treadmill speed at which women walked at 100 steps/min was 2.4 ± 0.4 mph which elicited an oxygen consumption of 9.5 mL•kg•min, or 2.7 ± 0.7 METs. There was no significant difference between METs at 3.0 mph and the conventional 3 MET cut point for moderate-intensity PA ( < 0.05). There was a moderate and significant relationship between METs and cadence (2nd trimester: r = 0.51; 3rd trimester: r = 0.42). Current data indicate for the first time that the traditionally used 3 MET cutoff for moderate-intensity activity is appropriate for pregnant women despite metabolic alterations associated with pregnancy. This may have important implications for exercise prescription in pregnant populations.
证据表明，每分钟 100 步的节奏表明中等强度阈值为 3 个代谢当量（METs），但这仅在非孕妇中描述过。由于怀孕期间代谢变化是明确的，因此本研究的目的是确定孕妇中相当于 3 METs 的行走节奏是否与非孕妇人群相似。怀孕的女性（n=29；年龄=30.3±3.2 岁，妊娠龄=23.9±6.6 周）在妊娠中期或晚期（妊娠 12 周以上）完成了三个阶段的跑步机行走，速度分别为每分钟 5 分钟：2.5、3.0 和 3.5 英里/小时（mph）。每分钟测量一次耗氧量（VO2）和心率（HR），并计算每个阶段的 MET 值。通过 OptoGait 步态分析系统实时连续监测行走节奏。在三个标准化速度阶段之后，参与者以每分钟 100 步的速度完成了一个额外的阶段，同时还收集了 VO2 和 HR。使用单样本 t 检验比较每个阶段的 MET 值与启发式 3 MET 截止值，并计算 Pearson 相关系数以评估节奏与 METs 之间的关系。平均节奏随着三个阶段的进行而呈线性增加（2.5 mph=103.7±4.5，3.0 mph=112.5±5.3，3.5 mph=120.4±6.2 步/分钟），MET 值也随之增加（2.5 mph=2.7±1.7，3.0 mph=3.2±0.8，3.5 mph=4.3±1.8 METs），无论妊娠时间如何。女性以 100 步/分钟行走的平均跑步机速度为 2.4±0.4 mph，耗氧量为 9.5 mL·kg·min，或 2.7±0.7 METs。在 3.0 mph 时的 MET 值与传统的 3 MET 中等强度 PA 截止值之间没有显著差异（<0.05）。METs 与节奏之间存在中度且显著的关系（中期妊娠：r=0.51；晚期妊娠：r=0.42）。目前的数据首次表明，尽管与妊娠相关的代谢变化，但传统上用于中等强度活动的 3 MET 截止值对于孕妇是合适的。这对于孕妇的运动处方可能具有重要意义。
