## 1 Introduction  
The gait perturbations refer to disruptions or disturbances in the normal walking pattern and can be intentional or unintentional. They are widely employed in research and clinical settings to investigate gait adaptations, balance control mechanisms, and rehabilitation strategies [1, 2]. Based on the literature, gait perturbations are typically categorized into three main types: external, internal, and cognitive perturbations [3, 4]. External perturbations result from outside forces or environmental changes and commonly include tripping, slipping, push/pull forces, and oscillatory movements [5]. These simulated scenarios are crucial because they offer a controlled method for studying real-world fall mechanisms. However, the relevance of such simulations must be linked to actual fall circumstances. Sudden treadmill belt accelerations closely mimic real-life tripping or slipping events by unexpectedly altering foot-ground dynamics, inducing destabilization. This resemblance allows researchers to analyze balance-recovery strategies under safe and repeatable conditions, thereby bridging the gap between experimental setups and everyday fall risks. In the context of anterior-posterior perturbations, the literature presents various terminologies, often describing them as \"tripping-like\" or \"slipping-like\" disturbances. A trip generally involves the swing leg encountering an obstacle during its forward motion, usually resulting in a forward-directed fall. Conversely, a slip occurs when the stance foot loses traction with the ground surface, leading to a sudden displacement either forward or backward. In experimental studies using split-belt treadmills, slipping effects are typically simulated by accelerating one treadmill belt, which causes the stance foot to move backward, thereby increasing the risk of a forward fall. Alternatively, decelerating or abruptly halting one belt can cause the stance foot to displace forward, which may result in a backward fall [6]. Pushing or pulling is the application of sudden forces to the body or upper extremities to cause imbalance during gait. Oscillatory perturbations arise from a moving or oscillating platform beneath the individual to introduce rhythmic disturbances into their gait pattern. Internal disruptions involve manipulating internal factors of the individual's body. They may include altered sensory input (modifying the sensory feedback received through visual, vestibular, or somatosensory signals), muscle weakness or fatigue, and altered stiffness of joints. Cognitive perturbations involve introducing cognitive challenges or distractions during gait to study attentional demands and dual-task performance [7]. [PERSON] [8] showed that unexpected falls or loss of balance during gait occur most often due to tripping or slipping in young and elderly populations alike. At this point, it is worth emphasizing that gait responses in the elderly and young may differ due to various factors, such as age-related changes in sensorimotor function, muscle strength, and balance control [9; 10]. Elderly individuals may exhibit a delayed response to perturbations compared to younger individuals. Age-related changes in processing speed and neural transmission can result in slower reaction times [11]. Elderly individuals may have reduced balance and stability [12], making them more vulnerable to perturbations. It can be explained by an age-related decline in muscle strength, joint flexibility, and sensory functions [13; 14]. Older people also apply some strategies to maintain proper neuromuscular control, like decreasing propulsive power generation during push-off [15]. On the other hand, young people tend to show a faster and more immediate response to perturbations due to having more efficient sensorimotor systems and better coordination. They can also more effectively engage muscles to counteract the forces and maintain balance [16].