Effects of Seat Height and Backrest Inclination on Body Pressure Distribution and Subjective Comfort in Seat Design for the Elderly

Adopting a human-centered approach, this study investigates the influence of seat parameters on comfort for elderly users. Twenty healthy older adults (61–70 years) assessed age-friendly seats with varying seat heights (knee popliteal height H mm, H − 50 mm, H − 25 mm, H + 25 mm, and H + 50 mm) and backrest inclinations (90°, 105°, 120°, 135°). Body pressure distribution analysis and subjective comfort evaluations were conducted to assess the impact of these parameters. Key findings demonstrated that optimal subjective and objective comfort ratings were achieved at a seat height of H mm or H − 25 mm combined with a backrest inclination of 105°. Seat height showed a positive correlation with contact area, while exhibiting negative correlations with average pressure and maximum pressure. Regional comfort (feet, calves, coccyx, anterior thighs) exhibited significant positive correlations with overall comfort (p < 0.01). Furthermore, increasing the backrest inclination angle led to a higher-pressure gradient, and slippage perception negatively correlated with comfort (p < 0.05). This research confirms that the parameter optimization—specifically height and backrest inclination—effectively optimizes pressure distribution and significantly enhances sitting comfort for the elderly. The findings provide a scientific basis for designing comfortable, age-friendly seating solutions that support sustainable quality of life.