## 1 Introduction  
Lower extremity movement during seated cycling is a cyclic motion that predominantly occurs in the sagittal plane. It is also constrained to the pedal/crank path around the bottom bracket. In seated conditions, these limit cyclists to optimize the pedaling technique by applying the force in two directions, vertically and in an anterior-posterior direction. Any medial-lateral force (FML) applied to the pedals during cycling in a seated position is considered as a waste and does not contribute to the pedaling. For these reasons it has often not been measured nor quantified [1, 2]. Even though several studies used instrumented pedals that allowed 3-dimensional force measurements [1], some research assumed that the leg movement during cycling is confined to the sagittal plane [3, 4]. However, medial-lateral movement of the knee is widely present during cycling and is often linked to overuse injuries [5, 6]. As demonstrated by [PERSON] et al. [7] this movement can be caused by the FML on the pedals and varus/valgus moments. This was further demonstrated by [PERSON] et al. [6] who found changes in varus and valgus knee loads at different knee positions (knee adduction/abduction) during stationary cycling. It is worth noting, however, that FML at the pedals while cycling at a workload of 225 W and cadence of 90 revolutions per minute (rpm), peaked at approximately 40 N with supporting varus/valgus moment of 1.35 N-m [7]. [PERSON] et al. [5] showed a close link between previously injured cyclists and knee kinematics in the frontal plane. They demonstrated that symptomatic cyclists move knees more medially compared to non-symptomatic cyclists, which could consequently result in a higher FML. These studies showed the importance of the multi-dimensional kinematics and dynamics in joint loads assessments. However, it remains unknown how different pedaling conditions (cadence, workload, etc.) affect the magnitude of the FML. Several studies examining the effectiveness of pedaling and the effects of mechanical constraints (e.g., cadence, seat position, etc.) used only vertical and anterior-posterior components for force computations and neglected or did not measure the FML [2,8]. However, to accurately assess the effect of a mechanical constraint, particularly when the constraint affects the inertial moments of the lower extremity (e.g., cadence, workload, etc. ), the FML could play a role in the force parameters calculations [9]. To date, there is little research separately assessing the amplitude of the FML [7,10] and no research that has systematically evaluated the changes in the FML component across different pedaling conditions. One of the most common measures of knee movement in frontal plane is Q-angle, defined as the angle between the tibia and femur in frontal plane. Pedal FML component could be generated due to excessive range of motion in Q-angle. Although moderate correlations (r\({}^{2}\) = 0.52-0.74) were found between some anatomical characteristics of the foot, Q-angle and lateral knee moments, there is no clear evidence of a cause-and-effect relationship between the FML and Q-angle [11]. Furthermore, the lack of research interest in the FML component means it is unclear how the magnitude and temporal characteristics of the FML change with cadence or workload, or if it correlates with the Q-angle. It has been previously shown that the risk of a knee injury (e.g., anterior knee pain or patellar tendinitis) is increased if the lower leg is in an abducted position when a knee extensor moment is generated [5]. An abducted lower leg position places the knee medially in respect to the ankle, which can disrupt the knee extensor mechanism [5]. Therefore, to minimize the risk of a knee injury occurrence, one should strive towards smaller FML and less adducted lower leg. The aim of this study was to examine (1) how FML changes at different cadences and workloads and (2) if frontal plane kinematics of the lower limb will correlate with the temporal characteristics of the FML.