# Physiological Responses Related to Sitting Comfort Due to Changes in Seat Parameters
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Part 2 (Ottoman-Reclining)**} & \multicolumn{3}{c}{**Part 3 (Slab-Neutral)**} \\ \cline{2-7}
**Index** & \
\begin{tabular}{c} **Mean of** \\ **Difference (SD)** \\ \end{tabular} & **t** & \(p\)**-Value** &
\begin{tabular}{c} **Mean of** \\ **Difference (SD)** \\ \end{tabular} & **t** & \(p\)**-Value** \\ \hline \((\theta+\alpha)/\beta\) of Cz & \(-0.19\) (0.63) & \(-2.29\) & \(0.026\) & \(0.11\) (0.45) & \(1.89\) & \(0.063\) \\ \((\theta+\alpha)/\beta\) of C3 & \(-0.02\) (0.46) & \(-0.30\) & \(0.762\) & \(-0.01\) (0.60) & \(-0.07\) & \(0.947\) \\ \((\theta+\alpha)/\beta\) of Cat & \(-0.15\) (0.43) & \(-2.63\) & \(0.011\) & \(0.12\) (0.63) & \(1.44\) & \(0.155\) \\ \((\theta+\alpha)/\beta\) of Pe & \(-0.24\) (1.04) & \(-1.77\) & \(0.081\) & \(0.29\) (1.12) & \(1.83\) & \(0.072\) \\ \((\theta+\alpha)/\beta\) of P3 & \(-0.16\) (0.96) & \(-1.28\) & \(0.204\) & \(0.13\) (1.10) & \(0.90\) & \(0.374\) \\ \((\theta+\alpha)/\beta\) of P4 & \(-0.19\) (1.00) & \(-1.50\) & \(0.140\) & \(0.27\) (1.12) & \(1.90\) & \(0.062\) \\ RRI (ms) & \(21\) (33) & \(4.96\) & \(<\)0.001 & \(0\) (29) & \(0.06\) & \(0.953\) \\ LF/HF & \(-0.36\) (1.17) & \(-2.22\) & \(0.030\) & \(-0.09\) (1.51) & \(-0.46\) & \(0.646\) \\ HF content & \(0.07\) (0.20) & \(2.63\) & \(0.011\) & \(0.03\) (0.20) & \(1.29\) & \(0.202\) \\ Respiration rates (Hz) & \(0.007\) (0.028) & \(1.80\) & \(0.078\) & \(0.005\) (0.028) & \(1.48\) & \(0.145\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._activity as part of the regulatory mechanism for maintaining circulatory balance [34]. Both reclining and using the Ottoman also led to increase in RRI, although to a lesser extent compared to the supine position. Furthermore, reclining led to decrease in the respiration rate. However, the slab had no significant influence on autonomic activities. These findings suggest that autonomic activity may be more influenced by joint angle and postural angle relative to the ground than by pressure distribution on the user's body. Our findings have important implications for the evaluation of relaxation and seat design. In general, when people experience relaxation, theta and alpha waves in brain activity increase, while beta waves decrease [35; 36]. Additionally, it is known that parasympathetic nervous activity becomes more dominant than sympathetic activity during relaxation [19; 37; 38]. The present study suggests that even when users experience an overall sense of relaxation due to changes in seat parameters, brain activity, and autonomic activity function independently depending on whether it is a result of tactile stimulation to the body or a change in the body's postural angle. Therefore, it has become evident that comprehensive evaluation of both the user's central nervous system activity and autonomic nervous system activity is necessary when designing seat parameters to enhance the user's level of relaxation. The restricted physical condition of participants is one of the limitations of this study. Differences in the participants' physical characteristics, such as height, weight, and body mass index, could potentially lead to variations in seat pressure distribution and posture angles, even when the same seat parameters are applied. These variations, in turn, may result in changes in autonomic and brain activity. Moreover, the present study was limited in terms of the number of seat parameters examined. To address these limitations, future studies should consider the user's physical condition as a factor and investigate the effects of additional parameters, such as armrests, backrest folds, and combination of those parameters.