## 4 Discussion  
The present study evaluated whether EMG analysis could effectively reflect ergonomic improvements for commuter bike users by investigating muscle recruitment patterns in performance- and comfort-oriented saddle positions. The findings indicate that specific bike-fitting methods contribute to an increased sense of comfort and relaxation among participants. This is consistent with other reported subjective improvements by cyclists who experienced different saddle adjustments [11]. Notably, our data suggest that an individually optimised saddle position (P5)--determined through a combination of comfort feedback and professional fitting--may reduce the overall muscle activity in the lower extremity and spinal stabilising muscles (compared to P1-P4 positions), supporting the hypothesis that a decrease in EMG activity can quantify ergonomic improvements. Moreover, Statistical Parametric Mapping (SPM) analysis revealed differences in muscle activity patterns across the entire pedalling cycle between the tested saddle positions. Specifically, the comfort-oriented positions were associated with lower levels of sustained muscle activity, potentially due to a redistribution of load that minimises muscular demand on stabilising muscles during propulsion. This finding suggests that comfort-oriented adjustments lead to more efficient muscle recruitment. This may reduce the cumulative muscular load and perceived exertion, aligning with the hypothesis that ergonomic optimisation decreases the energy cost for the cyclist. Additionally, a literature overview by [PERSON] et al. [11] discusses modern biomechanical technologies for bike-fitting professionals, emphasising the importance of personalised adjustments in enhancing comfort and performance. These findings align with the hypothesis that ergonomic optimisation decreases the energy cost for cyclists by promoting more efficient muscle recruitment and reducing perceived exertion. Specifically, the EMG analysis of the tibialis anterior (TA) muscle across different cycling positions indicates that position P3 (LeMond saddle height with low handlebars) elicits the highest muscle activity, with significant variations occurring predominantly during critical phases of the cycling cycle. Significant differences suggest that TA activation varies notably between the different cyclist positions, particularly during the descending phase of the first activity peak and most of the second peak. This variation could be attributed to the biomechanical and neuromuscular adaptations required to maintain different cycling postures, significantly the more enormous workload exerted on the foot by the Lemond method. The consistent highest EMG activity in position P3 indicates that this position may induce more significant muscular effort in the TA, potentially due to altered kinematics or increased demand for muscle stabilisation. For pair P4/P5, the SPM analysis revealed additional differences in activity for TA muscle. During the initial phase of the cycle, position P4 showed higher muscle activity than P5, suggesting that P4 demands greater initial activation of the RTA muscle. This could be due to differences in pedal force application or cycling posture, requiring the muscle to work harder to maintain stability and generate force. Conversely, in the latter phase of the cycle (70-100%), position P5 showed slightly higher activity, indicating that this position may require more muscle engagement for recovery or stabilisation towards the end of the pedal stroke. On the other hand, for pairs P1/P5 and P2/P5, increased TA activity is easily observable during the extension phase of the pedalling cycle. Authors believe that [PERSON]'s method used for P1 (aft saddle with low handlebars) and P2 (aft saddle with high handlebars) resulted in a significant shift of the central of mass (CoM) towards the rear wheel. Hence, calf muscles were not required to stabilise the foot for the first 50% of the cycle.