## 4 Discussion
The analysis indicated that position P5 elicited higher muscle activity during the initial peak, while position P1 showed more significant activity during the second peak. Moreover, the EMG activity of the TA muscle shows two distinct peaks throughout the cycle. During the first peak, which occurred from approximately 0% to 25% of the cycle, position P5 elicited higher muscleactivity than position P2. Conversely, during the second peak, which occurred between 75% and 100% of the cycle, position P2 demonstrated higher muscle activity. Significant differences between the two positions were observed primarily in the late phase of the cycle. These results suggest that position P5 might require greater initial activation of the TA, possibly due to variations in pedal force application or posture. In comparison, position P2 demands higher activation towards the end of the cycle. Also, the EMG analysis of the Vastus Lateralis Obliquus (VLO) muscle across different cycling positions brought exciting results. Particularly when comparing position P1 (aft saddle with low handlebars) and position P2 (aft saddle with high handlebars) to the customised, comfort-oriented position P5. Both P1 and P2 demonstrated notably higher VLO muscle activity during the early (0-25%) and late (75-100%) phases of the pedalling cycle compared to P5, with significant differences observed in these specific periods. This heightened activity in P1 and P2 indicates increased muscle demand, particularly during the pedal stroke's initial force-generating and terminal phases. In the P1/P5 comparison, P1 consistently showed elevated VLO activity in the initial and terminal phases of the cycle relative to P5. This suggests that the lower handlebar height and aft saddle position in P1 may contribute to increased quadriceps activation, potentially linked to a more aggressive trunk angle and forward position, which could alter knee extension mechanics. Such positioning likely increases the VLO's role in stabilising the knee, especially when transitioning through the power (downstroke) and recovery (upstroke) phases. Similarly, in the P2/P5 comparison, P2 exhibited a significant peak in VLO activity early in the cycle (0-25%) compared to P5, indicating a higher demand for the VLO during the initial stroke phase. This may be due to P2's high handlebar height, which, despite being less aggressive, still places increased load on the quadriceps to maintain stability and control during knee extension. The pronounced early activation in P2 relative to P5 suggests that a higher handlebar setup with an aft saddle can create a biomechanical disadvantage by imposing additional stabilisation demands on the knee extensors, potentially leading to quicker fatigue over extended cycling periods. These findings emphasise the influence of cyclist posture on VLO activation, with P5 demonstrating reduced muscle engagement across critical phases of the cycle. This reduction in muscle activity in the custom-fitted position suggests that optimising for comfort and performance reduces unnecessary muscular effort, potentially lowering the risk of overuse injuries in the VLO. From an ergonomic perspective, these insights underscore the importance of personalised bike fitting strategies that balance comfort and muscular efficiency, particularly for commuter cyclists seeking comfort and injury prevention in prolonged rides. Building on the previous findings, comparisons between position P3 (LeMond saddle height with low handlebars) and P5, as well as position P4 (LeMond saddle height with high handlebars) and P5, further illustrate the impact of handlebar height and saddle configuration on VLO activation patterns. In both comparisons, positions P3 and P4 demonstrated significantly higher VLO muscle activity in the early phase of the pedalling cycle than P5, indicating increased muscular demands during the initiation of the pedal stroke.