Optimal Footrest and Backrest Angles for Young Adults’ Functional Recliners: An EEG and Subjective Assessment

Abstract

Functional recliners are increasingly used in urban homes, but their footrest and backrest settings are often adjusted without clear ergonomic guidance. This may reduce postural support, comfort, and ease of use. This study examined suitable footrest and backrest angles for young adults by combining electroencephalography (EEG) measurements with subjective comfort ratings. Twenty participants completed static sitting and reclining tests. The footrest angle was adjusted from 0° to 90°, and the backrest angle was adjusted from 110° to 130°. Alpha-band power was used as a physiological indicator of relaxation, while comfort was assessed using subjective ratings. The results showed that a 60° footrest angle produced the highest alpha-band power and was associated with high comfort ratings. For the backrest, the strongest alpha activity and favorable subjective comfort were observed at 125°. Alpha activity was most prominent in the parietal and occipital regions, particularly at O1, O2, and Pz. Based on the combined EEG and subjective results, a footrest comfort range of 40° to 70° is recommended for seated rest, while the backrest showed a broader and more gradual comfort transition during reclining. These findings provide preliminary physiological and subjective evidence for improving recliner design. Preset positions near the recommended angles may help improve adjustment efficiency and user experience for young adults.