Spatiotemporal, kinematic, force and muscle activation outcomes during gait and functional exercise in water compared to on land: A systematic review.

Background: Exercises replicating functional activities are commonly used in aquatic rehabilitation although it is not clear how the movement characteristics differ between the two environments. A systematic review was completed in order to compare the biomechanics of gait, closed kinetic chain and plyometric exercise when performed in water and on land.

Methods: Databases including MEDLINE, CINAHL, SPORTDiscus, Embase and the Cochrane library were searched. Studies were included where a functional lower limb activity was performed in water and on land with the same instructions. Standardized mean differences (SMD) and 95% confidence intervals were calculated for spatiotemporal, kinematic, force and muscle activation outcomes.

Findings: 28 studies included walking or running (19 studies), stationary running (three), closed kinetic chain exercise (two), plyometric exercise (three) and timed-up and go (one). Very large effect sizes showed self-selected speed of walking (SMD >4.66) and vertical ground reaction forces (VGRF) (SMD >1.91) in water were less than on land, however, lower limb range of movement and muscle activity were similar. VGRF in plyometric exercise was lower in water when landing but more similar between the two environments in propulsion. Maximal speed of movement for walking and stationary running was lower in water compared to on land (SMD>3.05), however was similar in propulsion in plyometric exercise.

Interpretation: Drag forces may contribute to lower self-selected speed of walking. Monitoring speed of movement in water assists in determining the potential advantages or limitations of aquatic exercise and the task specificity to land-based function.