Skervin, TK, Thomas, NM, Schofield, AJ, Hollands, MA, Maganaris, CN, O'Brien, TD, Baltzopoulos, V and Foster, RJ (2021) Using a stair horizontal-vertical illusion to increase foot clearance over an inconsistently taller stair-riser. PLoS One, 16 (9). ISSN 1932-6203

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Abstract

INTRODUCTION: Stair falls can be caused by inconsistent stair dimensions. During ascent, inconsistently taller stair risers lead to reduced foot clearances as the inconsistency goes unnoticed. A stair horizontal-vertical illusion increases perceived riser heights and foot clearance and could offset reduced foot clearances over inconsistently taller risers, though this might impact other stair safety measures. METHOD: Twelve participants (age: 22 (3) years) ascended a seven-step staircase under three conditions: i) all steps consistent in riser height (consistent), ii) a 1cm increase in step 5 riser height (inconsistent) and iii) a 1cm increase in step 5 riser height, superimposed with a stair horizontal-vertical illusion (illusion). Vertical foot clearance, foot overhang, and margins of stability were assessed over step 4, 5 and 6. Perceived riser height due to the illusion was determined through a computer perception test. A One-Way Repeated Measures ANOVA compared biomechanical variables between conditions. A One Sample t test compared perceived riser height to the true height. RESULTS: Over the inconsistent step 5, foot clearance reduced by 0.8cm compared to consistent. Illusion increased foot clearance by 1.1cm and decreased foot overhang by 4% compared to inconsistent. On step 4 the illusion led to more anterior instability compared to inconsistent. Illusion and inconsistent led to more mediolateral stability compared to consistent. The illusion increased perceived riser height by 12%. DISCUSSION: Foot clearance reductions over inconsistently taller risers can be offset by a stair horizontal-vertical illusion. Additional benefits included a safer foot overhang and unaffected stability over the inconsistent riser. Changes to step 4 stability might have resulted from leaning forward to look at the step 5 illusion. The stair horizontal-vertical illusion could be a practical solution for inconsistently taller stair risers, where a rebuild is usually the only solution.

Item Type:	Article
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport & Exercise Sciences
Publisher:	Public Library of Science
Related URLs:	https://www.ncbi.nlm.nih.gov/pubmed/34520496
Date Deposited:	27 Sep 2021 09:40
Last Modified:	27 Sep 2021 09:45
DOI or ID number:	10.1371/journal.pone.0257159
URI:	https://researchonline.ljmu.ac.uk/id/eprint/15551

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