## 4 Discussion
The lateral force presents a significant decrease maximally in the upper dead center (maximally \(-90.1\%\)) followed by the power phase (maximally \(-88.3\%\)). Decreases in the second half of the pedal cycle are visually observable though not significant due to high variation. The findings suggest that lateral load components reduce in function of the level of pedal assistance, resulting in a reduced pelvis movement and axial trunk movement. [PERSON] et al. state that the accelerations of the trunk center of mass, hips and shoulders increases when cycling at higher workloads [36]. As PA decreases the workload, the results are in line. The rider's weight is distributed over all points of contact between the bicycle and cyclist. Increasing the level of PA decreases the normal pedal force significantly in the power phase (maximally \(-63.3\%\)) and insignificantly though observable in the recovery phase. The variation in the recovery phase is notably higher as a lower workload results in higher variation [35]. The normal steer forces are significantly increased in the upper dead center (maximally \(25.5\%\)), power phase (maximally \(46.9\%\)), recovery phase (maximally \(27.1\%\)) and a small insignificant increase is observed in the lower dead center. Decreases in seat loading are visually observable (maximally \(-10\%\) over the whole cycle) though not significant due to high variation (maximally \(40\%\)). An ANOVA was performed with load values adjusted to the weight of the rider to analyze if the difference in body weight is the reason of the high variation. The variation is uninfluenced by the rider's weight, nor by inter-individual differences as gender, age, experience or flexibility level. All subjects present a very high within-subject variation, uninfluenced by the level of pedal assistance, implying they tend to hop around a central value. The findings suggest that the weight distribution over all points of contact between bicycle and cyclist is influenced by the level of pedal assistance. When the reaction forces on the pedals decrease due to an enlarged level of pedal assistance, the body weight is more supported by seat and steer. The same findings are presented by [PERSON] and [PERSON] for high workload levels [2]. Primary movements during pedaling are hip and knee extension in the downstroke phase (0-180 degrees) along with hip flexion in the backstroke phase (180-360 degrees). Knee flexion is less pronounced as it is mostly generated by the knee extension of the leg on the opposing pedal. The glutes extend the hip and are generally active from the upper dead center until the power phase [37]. Due to PA, an insignificant--though clearly visible--decrease in glutes activity is observed in the upper dead center and a significant decrease in the power phase (maximally \(-55.5\%\)). The quadriceps extend the knee and are generally active from the upper dead center until the power phase [38]. Due to PA, a significant decrease in quadriceps activity is observed in the upper dead center (maximally \(-64.2\%\)) and in the power phase (maximally \(-44.3\%\)). The hamstrings are the knee flexors and hip extensors and are active through the whole pedal cycle as they also support the knee extensors to regulate the net joint moments. The literature presents varying results on the activation of the hamstrings. [PERSON] et al. presented activation between 150 degrees and 270 degrees [20], while [PERSON] et al. presented activation between 60 degrees and 240 degrees [37]. In this research, the hamstrings are singularly inactive in the recovery phase. An insignificant, though visually noticeable, decrease is observed in the lower dead center and a significant decrease is observed in the upper dead center (maximally \(51\%\)) and the power phase (maximally \(-48.9\%\)). In the phases where muscles are most active, a decreased activity level in function of the amount of PA is observed. In the phases where muscles are less active, they present no observable differences.