## 4 Discussion
### Kinematic Discussion  
The main findings demonstrated in this study match with what [PERSON] et al. (2018) reported regarding the gait biomechanical parameters that might help therapists to predict the occurrence of knee osteoarthritis [23]. To clarify, the fluctuating in the knee kinematic parameters between declining the sagittal plane ROM, particularly the extension angle, and raising the adduction angle in the frontal plane could be considered as the early symptoms of knee osteoarthritis OA. Moreover, decreasing knee flexion angle was considered by [PERSON] et al. (2020) as one of the main walking kinematic changes that happen to the knee joint among osteoarthritis patients (OA) [21]. However, we did not find any increase in the ankle dorsiflexion angle or decrease in the ankle plantar flexion angle during the gait after CLS. This is opposite to the gait biomechanical findings of osteoarthritis patients (OA) that had been stated by [PERSON] et al. (2020) [21]. Although the hip abduction angle changed after CLS without any significant difference, it was the opposite point to what [PERSON] and [PERSON] (2014) reported regarding the effect of improper sitting posture on the lower extremities that could be avoided by changing the posture from static to dynamic regularly [18]. Therefore, [PERSON] et al. (2016) and [PERSON] (2015) advised the employees to separate each hour of static posture with a few minutes of dynamic movements to decrease the level of discomfort and protect the postural alignment [24; 25]. Comparing the CLS parameters with backward sitting by [PERSON] et al. (2016) and upright cross-legged sitting (one leg over another) by [PERSON] and [PERSON] (2011) and [PERSON] et al. (2020), it is determined that increasing hip flexion angle after CLS is consistent with the effect of the mentioned unhealthy postures [2; 10; 19]. However, decreasing the hip adduction angles and sagittal knee angles during walking after 20 min of CLS is inconsistent with what has been found during 7-10 min of backward leaning and 1-10 min of upright cross-legged sitting. On the other hand, the effect of CLS findings in the current study is directly in line with the characteristics of forward-leaning posture that had been completed for some volunteers for 7-20 min and considered an unhealthy position by [PERSON] et al. (2016), [PERSON] et al. (2019), and [PERSON] et al. (2020) [7; 26; 27]. In detail, it is claimed that increased hip sagittal ROM, particularly the flexion angle, that happened during the forward-leaningsitting position, could be the main cause of considering this position as unhealthy due to increasing the lumbar flexion that will be occurred accordingly. Unlike the yoga position that had been analysed by [PERSON] et al. (2018) and [PERSON] et al. (2005) [11; 14], CLS can increase the hip extension angle, ankle plantar flexion angle in the sagittal plane, and the knee vurus angle in the frontal plane, while the hip abduction angle and ankle dorsiflexion angle decrease during walking after CLS compared to before. However, the significant increase in the knee vurus angle after CLS is consistent with what [PERSON] et al. (2011) stated regarding the biomechanical parameters of obese people's gait [12]. In line with the ideas stated by [PERSON] et al. (2015) and [PERSON] et al. (2014) [16; 17], decreasing knee kinematics, particularly knee flexion, ROM can be considered a negative effect of improper sitting. This point is consistent with the main effects of CLS on the knee in the current study. However, decreasing the ankle plantar flexion angles can be dealt with as one characteristics of an unhealthy sitting position. This point did not match with what happened in the ankle after CLS in the current study. Therefore, based on the kinematic literature, there is no match between CLS influences with any influences of unhealthy sitting postures or any primary predicting signs of lower limb problems particularly knee osteoarthritis [2; 10; 18; 19; 23].