Postural instructions affect postural sway in young adults

Background: Instructions to exert effort to correct one's posture are ubiquitous, but previous work indicates that effort-based postural instructions can impair balance control in older adults with and without neurodegenerative disease. Although less-studied, young adults are at high risk of injurious falls. Research question: How do different postural instructions influence static balance in young adults? Methods: Single-session, counterbalanced, within-subjects design. Twenty young adults briefly practiced three different ways of thinking about their posture, then attempted to employ each way of thinking while standing on springy foam for 30 s with eyes open. Relax instructions were used as a baseline between experimental condi-tions. Effort-based instructions emulated popular concepts of posture correction using muscular exertion. Light instructions aimed at encouraging length and width while reducing excess tension. Postural sway was assessed with an inertial sensor at the low back. Results: Effort-based postural instructions increased path length and jerk of postural sway during quiet stance, relative to Light and Relaxed instructions. Significance: These results are consistent with previous work in older adults indicating that thinking of upright posture as inherently effortful impairs balance. Therefore, the common practice of instructing young adults to use effortful posture may impair their balance performance.