BACKGROUND

There is growing evidence that arm movements make a substantial and functionally relevant contribution to dynamic balance. Additional insight of the important role of arm movements may be gained by quantifying the effects of arm restriction on the performance of commonly recommended static balance tasks of increasing difficulty.

RESEARCH QUESTION

The purpose of the present study was to determine whether restricting/permitting arm movements influences postural sway during tasks of various levels of difficulty.

METHODS

A total of 20 healthy and physically active adults (females; n = 10; age, 20.7 ± 1.3 years) randomly completed (a) quiet standing postural control tasks of increasing difficulty (bipedal, tandem, unipedal) on a fixed and foam surface, and (b) a dynamic postural control task (Y balance test), under two different verbally conveyed instructions of arm position; (1) restricted arm movement and (2) free arm movement. Centre of pressure outcomes measured during quiet standing served as a measure of static balance performance.

RESULTS

The results showed that restricting movements of the arms elicited large magnitude (Cohen's d = 0.97 - 1.28) increases in mediolateral postural sway (P < 0.05) but not anteroposterior (P > 0.05) sway. These effects were only observed during challenging (tandem and unipedal) standing balance tasks. Restricting arm movements elicited a marked reduction in the Y Balance reach distance (all directions, P < 0.001, d = -0.53 to -1.15).

SIGNIFICANCE

The findings from the present study suggest that the contribution of the arms only become relevant when frontal plane balance is challenged. Moreover, the data indicate that arm movements are vital for the control of mediolateral postural sway.