Dynamic postural stability is more variable barefoot than in footwear in healthy individuals

Abstract

Balance has been explored as a risk to or consequence of various musculoskeletal injuries and falls. However, the influence of footwear on variables of dynamic balance is not well understood. The aim was to (1) compare dynamic postural stability while barefoot to wearing personal well-used footwear and (2) determine the influence of footwear mediolateral asymmetry on dynamic stability. One hundred and six healthy participants, aged 32.4 (SD 13.3) years, performed a double- to single-leg stance task while standing on two force platforms barefoot and in their own footwear. Medial and lateral outersole thickness and midsole hardness were measured for asymmetry. Variability of anterioposterior (SDFx) and mediolateral (SDFy) ground reaction forces (GRF), centre of pressures displacement (COPd), mean COP velocity (COPv), and time to stabilisation of both forces (TTSFx and TTSFy) were calculated. During double-leg stance, SDFy was more variable barefoot by 12.2% (95%CI: 1.2–24.3%, p = 0.028). Significant differences between barefoot and footwear of 13.8% (7.4–20.7%, p = 0.001), 25.9% (17.0–35.4%, p = 0.001), 16.5% (8.8–24.7%, p = 0.001) were measured during the transition phase for SDFx, COPd and COPv, respectively. Similar results were found for all these variables during single-leg stance. In contrast, TTSFx and TTSFy was quicker barefoot than in footwear by 11.9% (4.0–19.2%, p = 0.004) and 3.5% (1.2–5.7%, p = 0.003). Participants with asymmetric footwear had greater barefoot mediolateral variability (SDFy) during transition than those with symmetric footwear, similarly, during the shod single-leg stance phase. Healthy individuals respond differently to dynamic stability testing while barefoot than in their personal footwear. Footwear asymmetry should be considered when assessing dynamic stability.