Objectively assessing treadmill walking during the second and third pregnancy trimesters.

Area of Science:

• Obstetrics and Gynecology
• Exercise Science
• Biomedical Engineering

Background:

• Accurate measurement of physical activity (PA) during pregnancy is crucial for promoting health and quantifying intervention effects.
• Current PA measurement methods require refinement for the pregnant population.
• Understanding how pregnancy-related physiological changes influence PA monitor output is essential.

Purpose of the Study:

• To evaluate the output of PA monitors (Actigraph, NL1000, Yamax) during a controlled treadmill walking protocol in pregnant women.
• To assess changes in monitor output between 20 and 32 weeks of gestation.
• To determine if physiological changes during pregnancy affect PA monitor readings.

Main Methods:

• Forty-three pregnant women participated, wearing an Actigraph accelerometer, NL1000, and Yamax pedometer.
• Participants completed a 20-minute treadmill walking test at four different speeds (54, 67, 80, 94 m·min⁻¹).
• Measurements were taken at 20 and 32 weeks of gestation.

Main Results:

• Actigraph and NL1000 measures of PA (counts/minute, minutes of moderate-vigorous PA, steps) and Yamax steps decreased from 20 to 32 weeks gestation.
• Body girth circumference and activity monitor tilt increased significantly between the two measurement points.
• After controlling for body girth and monitor tilt, no significant differences in PA monitor outcomes were observed between 20 and 32 weeks gestation.

Conclusions:

• Physiological changes during pregnancy, such as increased body girth and monitor tilt, can impact PA monitor readings in controlled environments.
• Statistical adjustment for changes in body girth and monitor tilt may enhance the accuracy of activity monitors for pregnant women.
• Further research is needed to validate PA measurement tools for diverse pregnant populations.