Effects of Added Anterior Mass to Simulate Pregnancy on Shoulder and Pelvic Rotations in Human Walking

Abstract

The locomotor economy of females during pregnancy would have been an important selection pressure through human evolution, as evidenced by females in modern foraging societies that travel long distances when gathering food and contribute a large proportion of calories to the diet. This study aims to identify the effects of pregnancy on pelvic and shoulder rotations in human walking, and explore the possible implications of these variables for locomotor economy. A weighted vest with an anterior load was used to simulate pregnancy and vests with equally distributed weight to determine that any differences found were the result of weight distribution, and not the added weight alone. There was a decrease in hip rotation and stride length due to carrying an anterior load, which supports the hypothesis that a wider pelvic breadth in females may be advantageous to counteract these effects. While not significant, there was a smaller decrease in shoulder rotation when carrying an anterior load as opposed to an equally distributed load which may be due to the altered inertia of the trunk. Further research is needed with pregnant subjects to better understand these findings and to rule out any effects caused by the mechanics of the weighted vests.