Mimicking obesity and pregnancy by adding load mass elicits minor postural oscillations compared to backpack weight carrying.

Abstract

Structured abstract Objective An excess load mass of anterior or antero-posterior body part is encountered in pregnancy and android obesity, or gynoid obesity, respectively, whereas occupational backpack weight carrying occurs in soldiers, firefighters and school children. We questioned the consequences of different placements of added loads (backpack, anterior or antero-posterior, i.e., around the trunk) on the postural sway during upright standing. Methods Thirty six young subjects with normal body weight were examined. Cast iron disks were introduced into the backpack and/or the ventral pockets of a waistcoat (total added load = 30% of body weight). A baropodometric platform measured oscillations of the centre of pressure (CoP) at the end of a 10-min period of upright standing in double limb stance in control condition (no weight carrying) and at the end of each 10-min weight carrying session. A 10-min rest period elapsed between two consecutive carrying sessions. Results Backpack carrying elicited the highest changes in postural sway, increasing the CoP surface and length, the velocity of anteroposterior and mediolateral deviations and the magnitude of mediolateral deviations. On the other hand, anterior load mass placement only increased the velocity of changes in the anteroposterior CoP deviation and antero-posterior weight carrying solely increased the mediolateral CoP deviation. Conclusion Added load mass mimicking pregnancy, android or gynoid obesity elicits discrete changes in postural control compared to backpack weight carrying which may accentuate the risk of fall during occupational activities. Clinical trial registration CPP Sud Mediterranee 1, September 9th 2015, N° 2014-AO1969-38.