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Pezhmanfard P, Mohebbi I, Azadi F, Mokhtari Nia H R. The Effect of Manual Load Holding Magnitude and Mode on Postural Sway in Healthy Community-dwelling Older Adults in Tehran, Iran. Salmand: Iranian Journal of Ageing 2022; 17 (3) :432-445
URL: http://salmandj.uswr.ac.ir/article-1-2295-en.html

Objectives Due to the decline in the function of balance system in older adults and the importance of having an active old age, it is very important to maintain independence during daily living activities such as shopping, holding and carrying an external load. This study aims to determine the effect of external load magnitude and holding mode on the postural sway during standing in healthy community-dwelling older adults.
Methods & Materials In this quasi-experimental study, 15 healthy community-dwelling older adults in Tehran, Iran (7 men and 8 women) with a mean age of 71.53±6.18 years who were independent in daily living activities such as shopping and carrying shopping bags were enrolled using a conveneince sampling method. The independent variables were holding manual loads with a magnitude of 0%, 5%, 10%, 15%, and 20 % of body weight in symmetrical (both hands) and asymmetrical (dominant or non-dominant hand) conditions, standing still on the force plate for 30 seconds. Dependent variables included the amount and velocity of the displacement of the center of pressure (COP) in two anteroposterior and mediolateral directions and the area of the COP displacement.
Results The effect of holding manual loads symmetrically and asymmetrically and the manual load magnitude on the amount and velocity of COP displacement in anteroposterior direction was signifcant, while their interaction effect was not significant on any variables. The paired t-test results showed that the amount and velocity of COP displacement in anteroposterior direction at asymmetric condition was significantly different compared to the symmetrical condition, but there was no significant difference between holding with dominant and non-dominant hands. The amount of COP displacement in anteroposterior direction with 5%, 10%, 15% and 20% of body weight were higher and statistically significant compared to the load magnitude of 0% (P<0.05). The effects of load holding mode and load magnitude were not statistically significant on any of the COP variables in the mediolateral direction. 
Conclusion Holding external loads asymmetrically with any magnitudes can increase the amount and velocity of COP displacement in the anteroposterior direction. For preventing falls, it is recommended for the elderly to pay attention to the fact that holding an external load with two hands is less challenging to the balance system than holding with one hand, whether dominant or non-dominant. In terms of the load magnitude, an external load with 5% of body weight can challenge the balance system compared to the situation without external load. With some exceptions, there is no difference between loads of 5%, 10%, 15% and 20% of body weight.