Within session reliability of center of pressure measures to assess lower limb postural control under alternative auditory conditions

BACKGROUND: Postural control is maintained through sensory information from visual, audio-vestibular and somatosensory inputs. When one of these senses are challenged, individuals shift their reliance more heavily onto other inputs to maintain postural control. Manipulation of vision to progress and regress lower limb rehabilitation has been researched extensively however, there is limited research on the effects of audio stimuli on postural control. In order to assess how audio stimuli can be manipulated for postural control and rehabilitation purposes, a reliable method must be identified.

RESEARCH QUESTION: When testing postural control under alternative auditory conditions, is there an acceptable level of reliability for lower limb center of pressure measures?

METHODS: Thirteen healthy participants completed three 30 s single leg balance (SLB) trials in five auditory conditions (no sound, white noise, audio book, ear to ear and non-ear to ear) on a force plate in random order. Intraclass correlation (ICC) and coefficient of variation (CV) with 95 % confidence intervals were used to assess the reliability of the center of pressure (COP) anterior-posterior (AP), medial-lateral (ML) and total sway path (TSP) outcome measures.

RESULTS: The CV for each COP sway path measure remained under 10 %, ranging from 3.44 % to 7.28 %. Based on the ICC, reliability was excellent for all sway path COP outcome measures (ICC= 0.705-0.950), except no sound and white noise conditions in the AP direction which show low reliability scores (ICC= 0.39 0.42).

SIGNIFICANCE: Three 30 s SLB trials were sufficient to ensure excellent within session reliability of COP TSP, in ML and some AP directions during alternative auditory conditions.