Stable and Unstable Load Carriage Effects on the Postural Control of Older Adults

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Type Article
Original languageEnglish
Pages (from-to)178–185
Number of pages8
JournalJournal of Applied Biomechanics
Volume36
Issue number3
Early online date05 May 2020
DOI
Publication statusPublished - 01 Jun 2020
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Abstract

The aim of this study was to investigate the effects of backpack load carriage on quiet standing postural control and limits of stability (LOS) of older adults. Fourteen older adults (65 [6] y) performed quiet standing and a forward, right, and left LOS test in 3 conditions, unloaded, stable, and unstable backpack loads while activity of 4 leg muscles was recorded. Stable and unstable loads decreased postural sway (main effect η2p=.84, stable P < .001, unstable P < .001), mediolateral (main effect η2p=.49, stable P = .002, unstable P = .018) and anterior–posterior (main effect η2p=.64, stable P < .001, unstable P = .001) fractal dimension, and LOS distance (main effect η2p=.18, stable P = .011, unstable P = .046) compared with unloaded. Rectus femoris (main effect η2p=.39, stable P = .001, unstable P = .010) and gastrocnemius (main effect η2p=.30, unstable P = .027) activity increased in loaded conditions during LOS and quiet standing. Gastrocnemius–tibialis anterior coactivation was greater in unstable load than stable loaded quiet standing (main effect η2p=.24, P = .040). These findings suggest older adults adopt conservative postural control strategies minimizing the need for postural corrections in loaded conditions. Reduced LOS may also increase fall risk when carrying a load. However, there was no difference between unstable and stable loads for postural control variables.

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