# For Patients with Stroke, Balance Ability Affects the Leg Extension Angle on the Affected Side
## 4 Discussions  
We examined the physical impairments associated with leg extension angle during gait in patients, post-stroke. The present results demonstrated the association of leg extension angle with BBS, FMA-LL, and MI-LL. Consistent with our hypothesis, multiple regression analysis revealed that balancing ability, assessed by BBS, was a significant predictor of leg extension angle during gait in post-stroke patients. Our findings suggest that improving a patient's ability to balance would be useful in increasing the leg extension angle and improving gait speed in clinical practice. This novel study demonstrates the relationship between clinical physical impairment and leg extension angle. Leg extension angle had a significant positive relationship with the BBS. Previous studies have reported that the ability to balance, as assessed by BBS, is associated with step length and gait speed in post-stroke patients [44; 45; 46]. [PERSON] et al. [47] reported that balancing ability, assessed by the velocity and sway area of the center of pressure in the upright standing position, significantly relates to stride length during gait in chronic stroke patients. Our findings are consistent with the reported evidence pertaining to stride length and indicate that balancing ability is associated with the leg extension angle. The BBS, which includes both static and dynamic tasks, was used to assess balancing ability in this study. Walking with a substantial leg extension angle requires adequate balance control to avoid body fluctuation; therefore, the BBS score is expected to modulate the leg extension angle of the affected side during post-stroke gait. The leg extension angle also showed a significant positive relationship with the FMA-LL and MI-LL. Path analysis also showed that MI-LL indirectly impacted the leg extension angle on the affected side through balancing ability. There are inconsistent suggestions regarding the relationship between motor impairments of the affected lower limb and walking ability in patients, post-stroke. Previous studies report a significant relationship between walking speed and the muscle strength of an affected lower limb [48; 49; 50] and the severity of motor paralysis in stroke patients [51]. In addition, the motor function of the affected lower limb can be correlated with the leg extension angle [17] and spatiotemporal parameters, including cadence, step length, and stride length [52]. In contrast, other studies report that muscle strength is not significantly associated with gait parameters, including step length and gait ability (speed and distance) in stroke patients [53; 54]. [PERSON] et al. [55] reported that leg extension angles on the affected side were not consistent even with the same level of the FMA-LL, despite the correlation of the FMA-LL with gait speed. These contradictions might be explained by the indirect effect of motor function of the affected lower limb on the leg extension angle and gait speed observed in the model-derived path analysis. The effect of MI-LL on the leg extension angle of the affected lower limb and gait speed is likely elicited via BBS. Thus, although the FMA-LL and MI-LL are important factors in post-stroke gait, their effect on gait performance is limited. Leg extension angle has an indirect effect on gait speed through the increment of velocity on the affected side. Foot position, relative to the pelvis (i.e., the leg extension angle), influences the forward propulsion of the center of mass (COM). [PERSON]  
Figure 2: Path analysis for the effect of the Berg balance scale (BBS) and leg extension angle on gait speed. Numbers represent standardized coefficient values (\(\beta\)). Continuous arrows represent the statistically significant paths (\(p<0.05\)), and dashed arrows represent non-significant paths. * \(p<0.05\), **\(p<0.01\). et al.