title: The influence of the aquatic environment on the control of postural sway.
abstract: Balance training in the aquatic environment is often used in rehabilitation practice to improve static and dynamic balance. Although aquatic therapy is widely used in clinical practice, we still lack evidence on how immersion in water actually impacts postural control. We examined how postural sway measured using centre of pressure and trunk acceleration parameters are influenced by the aquatic environment along with the effects of visual information. Our results suggest that the aquatic environment increases postural instability, measured by the centre of pressure parameters in the time-domain. The mean velocity and area were more significantly affected when individuals stood with eyes closed in the aquatic environment. In addition, a more forward posture was assumed in water with eyes closed in comparison to standing on land. In water, the low frequencies of sway were more dominant compared to standing on dry land. Trunk acceleration differed in water and dry land only for the larger upper trunk acceleration in mediolateral direction during standing in water. This finding shows that the study participants potentially resorted to using their upper trunk to compensate for postural instability in mediolateral direction. Only the lower trunk seemed to change acceleration pattern in anteroposterior and mediolateral directions when the eyes were closed, and it did so depending on the environment conditions. The increased postural instability and the change in postural control strategies that the aquatic environment offers may be a beneficial stimulus for improving balance control.
authors.affiliation: Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada. Electronic address: andresa.marinho@mail.utoronto.ca.
authors.forename: Andresa R
authors.initials: AR
authors.lastname: Marinho-Buzelli
authors.affiliation: Department of Mechanical Engineering, University of Alberta, Donadeo Innovation Centre for Engineering, 9211-116 Street NW, Room 10-368, Edmonton, AB, T6G 1H9, Canada. Electronic address: hrouhani@ualberta.ca.
authors.forename: Hossein
authors.initials: H
authors.lastname: Rouhani
authors.affiliation: Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 407, Toronto, Ontario, M5S 3G9, Canada. Electronic address: k.masani@utoronto.ca.
authors.forename: Kei
authors.initials: K
authors.lastname: Masani
authors.affiliation: Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Department of Physical Therapy, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada. Electronic address: m.verrier@utoronto.ca.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Verrier
authors.affiliation: Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 407, Toronto, Ontario, M5S 3G9, Canada. Electronic address: milos.popovic@utoronto.ca.
authors.forename: Milos R
authors.initials: MR
authors.lastname: Popovic
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D006875:Hydrotherapy; D008297:Male; D009068:Movement; D004856:Postural Balance; D060726:Torso / Q000502:physiology*; D055815:Young Adult
keywords: Aquatic environment; Center of pressure; Postural sway; Quiet standing; Trunk acceleration