## 4 Discussion  
To the best of our knowledge, this study was the first study to investigate the effect of vertical stimulation training on physical and cognitive function and sleep quality in older individuals with dynapenia residing in long-term care facilities. The results revealed significant differences in HGS and IADLs in the experimental group after the intervention compared with before the intervention, whereas no such significant differences were observed in the control group. These findings are consistent with those of [PERSON] and [PERSON] [22], who observed significant differences in grip strength and IADLs after WBV training compared with before such training among community-dwelling older adults. Rapid vibrations stimulate sensory receptors in the brain and motor receptors in the joints, muscles, and ligaments, activating brain reflexes and proprioceptive feedback loops. This mechanism enhances whole-body proprioception and motor function and promotes the strengthening of neuromuscular functions, thereby improving muscle reflexes and brain nerve circuit control. Furthermore, regarding cognitive function, the experimental group in the present study demonstrated significant improvements in attention, calculation ability, and memory after the intervention. [PERSON] et al. [23] mentioned that vibration stimulated brain sensory receptors and spinal motor receptors in joints, muscles, and ligaments, activating brain reflexes and proprioceptive feedback loops, thereby enhancing whole-body proprioception and motor function and promoting the strengthening of neuromuscular functions, aiding in better muscle reflexes and brain nerve circuit control. [PERSON] et al. [11] also pointed out WBV stimulated circulation and enhanced blood flow to the brain, which could improve oxygen and nutrient delivery, supporting cognitive processes and overall brain health. These findings are consistent with those of [PERSON] et al. [24], who conducted an RCT to investigate the effect of cognitive training on cognitive and physical function in older adults. In that study, an experimental group underwent cognitive training three times a week for 12 weeks, whereas a control group received routine daily care without cognitive training. That study observed significant differences in memory and language abilities in the experimental group after the intervention compared with before the intervention, indicating improvements in cognitive and physical function in the analyzed older adults. Similarly, [PERSON] et al. [23] conducted a study involving 21 older participants. In that study, an experimental group underwent 12 weeks of regular strength training, whereas a control group underwent no intervention exercises. Their findings revealed improvements in cognitive function in the experimental group, with significant differences observed between pretest and post-test; that result is consistent with that of the present study. In the present study, the experimental group exhibited significant differences in sleep quality, sleep latency, sleep duration, and sleep efficiency between pretest and post-test, whereas no such significant differences in sleep parameters were observed in the control group. [PERSON] et al. [11] mentioned that WBV could stimulate blood flow and enhance cardiovascular function, which may promote better tissue oxygenation and metabolic waste removal, contributing to improved sleep. [PERSON] et al. [25] also pointed out that vibrations  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multicolumn{2}{c}{**Post-Test**} & \multicolumn{2}{c}{**Pre-Test**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{\(p\)**-Value**} & \multirow{2}{*}{\( \begin{array}{c}\textbf{Group}\times\\ \textbf{Time}\end{array} \)} & \multirow{2}{*}{\(p\)**-Value**} \\  & & & & & & & \\ \hline Cognitive function & \multirow{4}{*}{ \begin{tabular}{c} Experimental \\ Group \\ Control Group \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} 20.19 (0.78) \\ 18.03 (0.07) \\ \end{tabular}  } & \multirow{4}{*}{