## 4 Discussion  
This study evaluated the effects of home-based training using a vibrational device, termed the \"Kenko Yusuri\", on functional recovery in patients with chronic post-stroke upper limb impairment. According to the FMA-UE scores, the shaking exercise group showed significantly greater improvements than the control group that engaged in conventional training. Notably, this intervention was particularly effective in patients with moderate impairment, suggesting that vibrational stimulation can enhance neuroplasticity and sensory-motor integration [37], potentially facilitating motor function recovery [38; 39]. The efficacy of the intervention was further supported by the results derived from the GLMM analysis, which provide a predictive model for quantification of the intervention's impact on functional improvements. Jiggling and vibratory exercises also reduce muscle spasticity, which is commonly observed among stroke survivors [40]. In this study, the use of a home-based shaking device significantly improved the total FMA scores of patients with moderate impairment, demonstrating the efficacy of the device in activating sensorimotor pathways [41], which are often underused in paralyzed upper limbs [42]. Vibratory stimuli enhance proprioceptive feedback, which is essential for the motor learning and rehabilitation of individuals with neurological impairments. Recent studies have investigated the effects of vibration stimulation on upper limb spasticity after stroke, specifically comparing the effectiveness of vibration stimulation of the tendons and muscle bellies [43]. Vibration applied directly to the flexor tendon showed significantly greater reductions in spasticity than when it was applied to the muscle belly or after regular stretching. Vibratory stimulation is consistent with the hypothesized mechanism that tendon stimulation is more effective because of its effect on the Golgi tendon organ, which plays an important role in regulating muscle tone [44]. Improvements in upper limb impairment with spasticity often necessitate the continuation of BoNT-A treatment for at least four sessions, alongside regular training [45]. However, progression toward functional improvement tends to plateau with prolonged treatment. Patients who have undergone >10 sessions of BoNT-A therapy typically show minimal functional enhancement, reaching a plateau in their recovery. For these long-term treatment patients, pain reduction is the primary goal and outcome, while spasticity control is essential for maintaining quality of life [46]. The patients in the present study underwent multiple BoNT-A treatments, suggesting that their upper limb function may have reached a plateau despite consistent self-training. These patients often continued regular BoNT-A treatment and self-training. Although initial improvements in motor function may have been observed, these gains plateaued over time. Therefore, the unchanged MAS scores in the present study may be attributed to a plateau effect. Nonetheless, similar to the control of spasticity achieved with BoNT-A treatment, continuous self-training remains crucial. In our study, patients with stroke used a shaking device at home, either independently or with family assistance. This approach aligns with emerging research suggesting that the engagement of patients in active movement is beneficial for recovery from paralysis. Recent research supports the idea that active participation in rehabilitation by patients with stroke can significantly enhance recovery outcomes [47]. This includes patients taking an active role in their recovery through home-based interventions, as these interventions have been shown to be effective for motor function recovery after stroke. Incorporating exercise and functional task practices into daily routines, as emphasized in recent guidelines, is crucial for motor recovery.