## 4 Discussion  
We studied the intra-segment coordination of the lower extremity and its variability during pedaling at different intensities. The results showed that the shank range of motion (ROM) in transverse significantly increased at a higher pedaling intensity and the foot ROM in the sagittal plane significantly increased in a higher pedaling intensity, which verifies our first hypothesis partially. The results of the present study are in line with the results of [PERSON] et al. (2019), who reported an increase in the knee and ankle ROM with increasing pedaling intensity [7]. They examined joint ROM at different pedaling intensities. The increase in shank ROM in a transverse plane at a higher pedaling intensity can increase the valgus and varus loading on the knee and increase the risk for overuse injuries on the knee. Moreover, the increase in foot ROM at a higher pedaling intensity indicates the increase of plantar/dorsi flexion of the foot at higher pedaling intensity. It highlights the ankle roles when increasing the pedaling intensity in cyclists. Figure 4: High abduction/adduction (AD/AB)-Shank AD/AB continuous relative phase (CRP) (**a**) and continuous relative phase variability (CRPV) (**b**) in different pedaling intensities. Figure 5: Shank flexion/extension (FL/EX)-Foot plantar flexion/dorsiflexion (PF/DF) continuous relative phase (CRP) (**a**) and continuous relative phase variability (CRPV) (**b**) in different pedaling intensities. The results show that there were not significant differences in the intra-segment coordination of the lower extremity and its variability between different pedaling intensities, rejecting our second and third hypotheses. Participants showed a positive continuous relative phase (CRP) during 0-20% (shank extension dominancy) and 80-100% (shank flexion dominancy) of pedaling, and a negative CRP at 20-80% of pedaling (high extension dominancy at 20-50% and thigh flexion dominancy at 50-80%) for thigh flexion/extension (FL/EX)-shank FL/EX coupling (Figure 2a). However, this coupling pattern was not significantly different between different intensities. This coupling pattern highlights the quadriceps and hamstring roles for shank extension and flexion, respectively, during the first and fourth quadrant phases of pedaling, and, also, the hip extensors and flexors role for thigh extension and flexion during the second and third quadrants of pedaling, respectively. The coupling pattern for thigh FL/EX-foot plantarflexion/dorsiflexion (PF/DF) followed a similar pattern to thigh FL/EX-shank FL/EX coupling (Figure 3a). This indicates thigh extension dominancy during the first quadrant, thigh flexion dominancy during the fourth quadrant, foot plantarflexion dominancy during the second quadrant (plantar flexor role), and foot dorsiflexion (dorsiflexor role) during the third quadrant of the pedaling cycle. Coaches and cyclists can use these patterns as a guideline to strengthen the muscles. In addition, these patterns may be utilized by physical therapists to design recovery exercises. Consistent with our results, [PERSON] et al., (2012) reported no significant differences in hip-knee and knee-ankle coupling between different work rate conditions [24], and no differences in segment and joint angles between different workloads has been reported [6]. However, contrary to our results, a change in lower extremity joint kinematics during different power outputs has been reported [7; 9], but these researchers compared singular joint mechanics during each power output situation. We conclude, although the hip, knee, and ankle joint kinetics vary between different power outputs, cyclists may change their motor strategy so their lower extremity segments and joint coordination patterns do not change significantly during different intensities. Participants showed thigh addiction dominancy during 0-45% of the pedaling phase, and thigh abduction dominancy during 65-100% of the pedaling phase for thigh abduction/adduction (AD/AB)-shank AD/AB coupling.