Effects of a new unstable sandal construction on measures of postural control and muscle activity in women

BACKGROUND: It is well established that unstable shoe constructions with rounded soles have the potential to induce acute and long-term effects on muscle activity during standing and walking. However, it is unresolved whether functional footwear with regularly shaped soles may have similar effects. OBJECTIVE: Thus, the objective of this study was to compare measures of postural control and muscle activity during quiet standing and locomotion for women using a new sandal construction with an unstable element integrated into the sole of the shoe (Biodyn sandal), a conventional stable control sandal, and a barefoot condition. METHODS: Twenty-two healthy women between the ages of 30 and 50 years participated in this study. During standing, sway area was analysed in monopedal and bipedal stance by means of a computerised balance platform. During walking, temporal and spatial stride-to-stride variability was determined using a pressure-sensitive treadmill. Surface electromyography data of lower leg muscles was simultaneously collected during stance and walk tests. RESULTS: With the Biodyn sandal, significantly larger sway area during bipedal stance (p