Characterizing Mechanical Efficiency in Pregnancy

Abstract

Pregnancy is an unique period in a woman’s life in which her body undergoes rapid and drastic changes. Historically, physical activity was thought to be dangerous during pregnancy and women were recommended to avoid engaging in most physical activities. Mechanical efficiency, the ratio of external work and energy required to perform a task, is an important consideration when addressing the safety of physical activity, but also when defining recommendations to this population. Currently, there is limited literature that characterizes the change in mechanical efficiency across pregnancy. Of the available literature, suboptimal methodologies were employed, resulting in conclusions that conflict with what would be expected. The purpose of this thesis was to characterize mechanical efficiency across gestation and to compare with non-pregnant women. Women performed a standardized treadmill task in early, mid, and late pregnancy, and energy dynamics were measured. Results showed that energy requirements and external work performed increased over time, and that these were in relation to gestational weight gain. Pregnant women did not exhibit a change in the efficiency of performing a walking task. Overall, these results add to the current literature that supports women’s engagement in physical activity during pregnancy.