## 4 Discussion  
The aim of this study was to test the hypotheses that (1) the FML would correlate with the knee frontal plane kinematics and (2) the FML would differ at different workloads and cadences. The results of the present study support the hypotheses and show a correlation between the Q-angle and the FML and demonstrate the differences in FML across different pedaling conditions. The FML has been often linked to overuse injuries [11]. The risk of anterior knee pain and patellar tendinitis could be increased if the lower leg is in an abducted position when a knee extensor moment is generated [5]. It was demonstrated that cyclists with history of the anterior knee pain display significantly more abduction (knee valgus) during the downstroke and remain in knee abduction during the upstroke [5]. The results of the present study show that a correlation between the temporal characteristics of the FML and QA is present during steady state cycling on a cycling ergometer. The link between the  
Figure 2: Absolute medial-lateral force (**A**) and normalized medial-lateral force (**B**) across the three cadence (C75, C85 and C95) and three workload (HIGH, MID and LOW) conditions. Statistically significant difference (\(p<0.05\)) between the conditions are marked with an asterisk (*). FML and frontal plane knee kinematics was previously demonstrated [11] but was limited to only specific data points (e.g., peak) and not across the entire force/motion pattern. Knee movement in the frontal plane plays a significant role in the FML production. However, it cannot be the only mechanism and other factors remain to be tested. It was also observed that certain amount of inter-individual variability exists (Figure 3) when the correlation between the knee movement and FML was drawn (correlation coefficients ranging between 0.57 and 0.97). Therefore, future research should also focus on factors associated with FML, with some emphasis on inter-individual difference. One of the factors that could play a role in the FML production could be the lateral stability/control of the hip. In particular, the activity of the gluteus medius as an important muscle for providing stability around the hip region, which is then directly transferred to the pedals over the knee and ankle joints. Root mean square of the absolute and relative FML was found to be different across the three tested workloads. Moreover, a post analysis revealed that the absolute FML was found greater, whereas the relative FML exhibited lower values during the HIGH  
Figure 3: An example of the Q-angle (dashed line) and normalized force (solid line) for a cyclist with a high (**A**) and low (**B**) cross-correlation coefficient. compared to LOW cycling conditions. Higher workload at the same cadence can only be achieved by applying more force to the pedals. It is therefore not surprising that the absolute FML was also increased. On the other hand, a reduction in relative FML during HIGH compared to LOW correlates with an increase in force effectiveness [8]. Increased force effectiveness observed during higher workloads has been often reported in the literature [14] and differences in IE among workloads were also observed in the present study. Results of this study suggest that the relative amount of the FML is reduced when pedaling technique is more effective. Even though the majority of previous biomechanical studies examining force effectiveness during cycling neglected FML component [1], it clearly plays a significant role in the calculations of the Ftot applied to the pedals, and consequently the IE. That itself would not be problematic if the relative contribution of the FML was always proportional to the Ftot applied to the pedals. However, results of this study showed that the magnitude of the FML is affected by cadence and workload. Hence, future studies using force effectiveness as a biomechanical parameter should use a three-dimensional force sensor.