Accelerometer use to assess physical activity in pregnancy - A validation study

Mukoma, Gudani Goodman
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Background Little is known about physical activity (PA) patterns in pregnancy. Previous epidemiological research suggests that most women do not participate in regular PA during pregnancy. However, these estimates are often based on the use of crude measures that are not validated and may be prone to error. Furthermore, given the limited research using objective, comprehensive and validated methods, there is currently no commonly accepted measurement tool used to assess PA during pregnancy. Aim The aim of this study was to assess the validity of accelerometer devices in measuring physical activity energy expenditure (PAEE) during pregnancy. Methods Pregnant women (n = 22) in their first trimester (<14 weeks, longitudinal) between the ages of 18- 40, were invited to participate. In addition, women in their 2nd and 3rd trimesters were invited for a once off testing (cross-sectional). All participants completed a 60-minutes submaximal walking protocol with different intensities, each having a 5-min duration. Participants wore one ActiGraph, Axivity and GENEActiv on the left wrist, and one ActiGraph on the waist. Energy expenditure was measured using the Oxycon. Physical activity for pregnant and nonpregnant women, at each stage of the walking protocol, was compared using the Wilcoxon ranksum test. The relationships between accelerometers, placement positions, and criterion validity were assessed using Pairwise correlation. Results Significant differences in energy expenditure estimates were observed when using the hip-worn ActiGraph (p=0.03) and GENEActiv (p=0.05) accelerometers between the pregnant and nonpregnant participants. In the pregnant participants, moderate significant correlations were found between the Axivity and GENEActiv accelerometers (r =0.43) at 15 minutes rest, and the ActiGraph-wrist and GENEActiv accelerometers (r =0.39) at 5km/h. When comparing placement position for the pregnant sample, significant relationships were observed between the ActiGraph worn on the hip versus the waist, but only during rest (r =0.56), 3km/hr (r =0.41) and 5km/hr (r =0.76). None of the accelerometers showed consistent correlation with the Oxycon for measuring energy expenditure during this protocol. Conclusion Although there were some relationships found between the pregnant and non-pregnant participants when measuring PA using ActiGraph-hip and GENEActiv accelerometers during the walking test protocol, and when comparing placement position of the hip versus the waist using ActiGraph accelerometers, in general, these accelerometers did not provide consistent correlations between each other or the Oxycon for both the pregnant and non-pregnant participants. As a result a clear pattern for measuring EE during PA was not observed, and further research is needed to confirm this data and provide an accurate tool for measuring PA during pregnancy
A dissertation Submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Medicine in the field of Biokinetics Johannesburg, South Africa 2019