Department of Kinesiology, University of Massachusetts Amherst, 160A Totman Building, 30 Eastman Lane, Amherst, MA, 01003, USA.
School of Community Health Sciences, Counseling and Counseling Psychology, Oklahoma State University, Stillwater, OK, 74078, USA.
Int J Behav Nutr Phys Act. 2019 Jan 17;16(1):8. doi: 10.1186/s12966-019-0769-6.
Previous studies have reported that walking cadence (steps/min) is associated with absolutely-defined intensity (metabolic equivalents; METs), such that cadence-based thresholds could serve as reasonable proxy values for ambulatory intensities.
To establish definitive heuristic (i.e., evidence-based, practical, rounded) thresholds linking cadence with absolutely-defined moderate (3 METs) and vigorous (6 METs) intensity.
In this laboratory-based cross-sectional study, 76 healthy adults (10 men and 10 women representing each 5-year age-group category between 21 and 40 years, BMI = 24.8 ± 3.4 kg/m) performed a series of 5-min treadmill bouts separated by 2-min rests. Bouts began at 0.5 mph and increased in 0.5 mph increments until participants: 1) chose to run, 2) achieved 75% of their predicted maximum heart rate, or 3) reported a Borg rating of perceived exertion > 13. Cadence was hand-tallied, and intensity (METs) was measured using a portable indirect calorimeter. Optimal cadence thresholds for moderate and vigorous ambulatory intensities were identified using a segmented regression model with random coefficients, as well as Receiver Operating Characteristic (ROC) models. Positive predictive values (PPV) of candidate heuristic thresholds were assessed to determine final heuristic values.
Optimal cadence thresholds for 3 METs and 6 METs were 102 and 129 steps/min, respectively, using the regression model, and 96 and 120 steps/min, respectively, using ROC models. Heuristic values were set at 100 steps/min (PPV of 91.4%), and 130 steps/min (PPV of 70.7%), respectively.
Cadence thresholds of 100 and 130 steps/min can serve as reasonable heuristic thresholds representative of absolutely-defined moderate and vigorous ambulatory intensity, respectively, in 21-40 year olds. These values represent useful proxy values for recommending and modulating the intensity of ambulatory behavior and/or as measurement thresholds for processing accelerometer data.
Clinicaltrials.gov ( NCT02650258 ).
先前的研究报告指出，步行步频（步/分钟）与绝对定义的强度（代谢当量；METs）有关，因此基于步频的阈值可以作为可行的替代值来衡量步行强度。
建立明确的（即基于证据、实用、四舍五入的）阈值，将步频与绝对定义的中等（3 METs）和剧烈（6 METs）强度联系起来。
在这项基于实验室的横断面研究中，76 名健康成年人（男性 10 人，女性 10 人，代表 21 至 40 岁之间的每个 5 岁年龄组，BMI=24.8±3.4kg/m）进行了一系列 5 分钟的跑步机试验，每次试验之间休息 2 分钟。试验从 0.5 英里/小时开始，以 0.5 英里/小时的增量增加，直到参与者：1）选择跑步，2）达到预测最大心率的 75%，或 3）报告 Borg 感知用力程度大于 13。步频由手动计数，使用便携式间接测热法测量强度（METs）。使用带有随机系数的分段回归模型以及接收器工作特征（ROC）模型来确定中等和剧烈步行强度的最佳步频阈值。使用候选启发式阈值的阳性预测值（PPV）来评估最终的启发式值。
使用回归模型，3 METs 和 6 METs 的最佳步频阈值分别为 102 步/分钟和 129 步/分钟，使用 ROC 模型，最佳步频阈值分别为 96 步/分钟和 120 步/分钟。启发式值分别设定为 100 步/分钟（PPV 为 91.4%）和 130 步/分钟（PPV 为 70.7%）。
21-40 岁人群中，100 步/分钟和 130 步/分钟的步频阈值可以分别作为中等和剧烈步行强度的合理启发式阈值。这些值可以作为推荐和调节步行行为强度的有用替代值，或者作为处理加速度计数据的测量阈值。
Clinicaltrials.gov（NCT02650258）。
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