Investigating the Effect of Backrest Angle and Lumber Prominence on Low back Muscle Activity in the Automobile: A Nigeria Perspective

Abstract

Six male subjects volunteered for a study into the effects of automobile seat backrest angle (110⁰ and 120⁰) and lumbar prominence (0 mm and 50mm). There were 2 x 2 possible factor-level combinations in this experimental design. Each subject participated in each experimental session twice. The sessions lasted for 1-hr. The root mean square (RMS) variation of the EMG was used to assess the stress imposed on the low back musculature. The dependent variable was the change in RMS (RMS) over time. By definition, the RMS value becomes more positive as low back muscle activity decreases. Backrest angle was found to have a statistically significant main effect (p<.05). For the selected vehicle package, a 120⁰ backrest angle was optimal. Lumbar support prominence was not found to affect low back muscle activity.

Keyword: backrest, lumber support, low back, design, muscle.