## 4 Discussion  
The main findings of the present study show that combined platform instability and reduced sensory input profoundly impact postural control, offering a method to destabilize and challenge balance across varying levels, even in healthy young individuals.  
More specifically, we first established that the baseline balance score of the participants were within the range for healthy young individuals [26], with 18 out of 25 participants (72%) on the left side and 19 out of 25 participants (76%) on the right side meeting this criterion. Furthermore, nearly all participants showed proper symmetry [22; 27] and functional reach [28; 29] at baseline.  
Once the different IL and SIS conditions were introduced, we observed an effect of decreasing sensory information as the instability level was increased, with faster movements recorded with vestibular strategy and high instability combinations. A similar trend was observed for the increase in chest volume, highlighting the effect of combining increased instability with reduced sensory input [30].  
Additionally, we observed that removing visual input (i.e., visual and vestibular strategies) had a greater impact on both chest movement velocity and volume rather than increasing instability (e.g., from 2 to 3 instability level). Furthermore, we also observed that more voluminous chest movements also tend to be faster, especially at higher instability levels or under specific sensory strategies [31].  
Furthermore, our results provide crucial insights into the human postural control system's adaptability. The complex sensory system used to maintain balance incorporates visual, vestibular, and proprioceptive (perception of joint and body movement) inputs [31; 32]. Each of these components contributes distinct information, which the brain integrates to ascertain the body's spatial position and make necessary adjustments to maintain balance.  
An essential factor to consider when assessing balance under various instability levels is the platform board's increased sensitivity to body sway at higher instability levels. Even minor body sways can trigger significant board movements, requiring less force to induce movement compared to lower instability levels. This heightened sensitivity to body sway  
Figure 9: The sequential increase in chest movement velocity (cm/s) and 95 th CI Ellipsoid Volume (cm\({}^{3}\)) with varying instability levels (ILs) and sensory integration strategies (SIS) in combination.  
underlines the importance of precise neuromechanical responses in maintaining balance and preventing falls.  
The integration of different instability levels and sensory system strategies can facilitate understanding their interplay in postural control. Maintaining balance under different instability levels and reduced sensory input highlights the challenging interaction between various neurological reflex loops, including the vestibulospinal and cerebellar pathways, which constitute the neural controller for postural control. The vestibular system, responsible for detecting head movements and spatial orientation, plays a pivotal role in stabilizing posture, particularly when visual or proprioceptive inputs are reduced. Proprioception, providing feedback on body position and movement, complements vestibular information to maintain balance. The cerebellum, deeply involved in coordinating motor responses, integrates these sensory inputs and fine-tunes postural adjustments. In this study, the significant increases in chest movement velocity and volume, especially under vestibular conditions at higher instability levels, can be attributed to the cerebellum's role in modulating rapid corrective movements in response to sensory input challenges. The cerebellum's ability to integrate proprioceptive and vestibular feedback is crucial for maintaining postural control when sensory inputs are disrupted [33; 34; 35]. The working mechanism of this approach is illustrated in Figure 10.