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.

The Use of IMMUs in a Water Environment: Instrument Validation and Application of 3D Multi-Body Kinematic Analysis in Medicine and Sport

“…Among kinetic variables, peak velocities and the power of UW motion were obtained using a single unit [27,28]. More recently, Marinho-Buzelli et al [29] examined the postural control in water through trunk acceleration parameters using two body-worn inertial sensors. With regards to sport contexts, most studies have focused on the temporal phase detection of front crawl swimming.…”

Changes in Posture Following a Single Session of Long-Duration Water Immersion

“…Changes in hydrostatic pressure and buoyancy that occur during water immersion result in an underloading condition which effectively reduces the corrective torque required to maintain equilibrium. 20,23 Ultimately, this may result in a shift toward an ankle strategy, which would be associated with greater AP Range of COP displacement 36 much like we observed (Figure 2). It is possible that this effect influenced AP COP Range for the unaltered sensory condition in our results.…”

“…3 Few studies have investigated the influence of water immersion on postural control in general. Furthermore, the focus among them is limited to postural sway while immersed, 20 comparisons between aquatic and land-based assessments, [21][22][23] or postural control following water-based exercise interventions. 24,25 In contrast, the purpose of this study was to examine the effects of long-duration exposure to underwater immersion on static, terrestrial postural control in a sample of veteran divers.…”

Effects of water immersion on quasi-static standing exploring center of pressure sway and trunk acceleration: a case series after incomplete spinal cord injury

“…1). The exact same instrumentation was used in the water and on land [9]. A waterproof force plate (AMTI, ORP-WP-1000, Watertown, USA) was used to collect COP parameters during quiet standing at a sampling frequency of 1000 Hz (Fig.…”

“…According to Tamburella et al, mean velocity or path length of COP, are most reliable and can reveal the balance impairment due to sensory and/or motor impairments that occur after iSCI [8]. We also examined the acceleration of the upper (xiphoid level) and lower trunk (lumbosacral joint level) during quiet standing to investigate whether immersion in water alters trunk movement during body sway [9]. On land, trunk acceleration has shown to be a sensitive, valid and reliable measure of mild postural balance impairments in individuals with Parkinson's Disease [10,11].…”