Marshall Mallory R, Montoye Alexander H K, George Ashley J
Samford University, 800 Lakeshore Dr., Birmingham, AL, 35229, United States.
Alma College, 614 W. Superior St., Alma, MI, 48801, United States.
Gait Posture. 2018 Sep;65:81-85. doi: 10.1016/j.gaitpost.2018.06.175. Epub 2018 Jul 19.
Pregnancy-related changes in walking speed, gait dynamics, and total physical activity have been reported in past research, but free-living step cadences and their rates of change across pregnancy have not been studied.
The purpose of this study was to describe free-living stepping cadence in pregnant women and examine differences between second and third trimester women. We hypothesized that physical activity walking cadences would be lower later in pregnancy.
Fifty pregnant women were recruited for this study and n = 45 was the analytic sample size; 46.7% were in their second trimester (13-25 weeks) while 53.3% were third trimester (≥26 weeks). Participants completed a survey of demographic characteristics and wore an accelerometer on their non-dominant wrist for 7-8 days. These accelerometer data were downloaded in 60-sec epochs, allowing for determination of min-by-min walking cadence, defined as steps/min. Mean steps/day, mean cadence, peak cadence (average cadence over the 30 min of highest cadence in each day), mean time spent in moderate- to vigorous-intensity physical activity (MVPA, time spent with cadence ≥100 steps/min), and mean daily time spent in several cadence ranges were calculated for each participant. Between-trimester differences were determined using independent-samples t-tests.
Average daily steps were 11,060.1 ± 2,955.3; 66.7% of second trimester and 54.2% of third trimester women met daily step recommendations of 10,000 steps/day, but 0.0% of the sample accumulated the recommended 150 min/wk of MVPA. There were no differences by trimester for cadence at any step rates (p > 0.05).
Overall, pregnant women accumulated high numbers of steps per day but at low cadences; neither daily steps nor cadence varied from second to third trimester. These data suggest that steps and MVPA recommendations are not equivalent and therefore should not be used interchangeably, especially during pregnancy.
过去的研究报道了与怀孕相关的步行速度、步态动力学和总体身体活动的变化，但自由生活状态下的步频及其在整个孕期的变化率尚未得到研究。
本研究的目的是描述孕妇自由生活状态下的步频，并检验孕中期和孕晚期女性之间的差异。我们假设孕期后期的身体活动步行步频会更低。
招募了50名孕妇参与本研究，分析样本量为n = 45；46.7%处于孕中期（13 - 25周），而53.3%处于孕晚期（≥26周）。参与者完成了人口统计学特征调查，并在非优势手腕上佩戴加速度计7 - 8天。这些加速度计数据以60秒的时间段进行下载，从而能够确定每分钟的步行步频，定义为步数/分钟。计算了每位参与者的平均每日步数、平均步频、峰值步频（每天最高步频的30分钟内的平均步频）、中度至剧烈身体活动（MVPA，步频≥100步/分钟的时间）的平均时长，以及在几个步频范围内的平均每日时长。使用独立样本t检验确定孕期之间的差异。
平均每日步数为11,060.1 ± 2,955.3；孕中期66.7%的女性和孕晚期54.2%的女性达到了每日10,000步的建议步数，但样本中0.0%的人积累了建议的每周150分钟的MVPA。在任何步频下，孕期之间的步频均无差异（p > 0.05）。
总体而言，孕妇每天步数积累较多，但步频较低；从孕中期到孕晚期，每日步数和步频均无变化。这些数据表明，步数和MVPA建议并不等同，因此不应互换使用，尤其是在孕期。
