# Perturbations During Gait on a Split-Belt Treadmill: A Scoping Review
## 3 Results
### Perturbations in the Anterior-Posterior (AP) Direction
#### 3.1.4 Summary of Results and Measurement Outcomes  
Nine papers extensively studied the slipping-like effect caused by accelerating one treadmill belt. [PERSON], et al. [30] found strong perturbations reduced dynamic stability, increased compensatory step time, and decreased the margin of stability (MoS) in young subjects. They also noted significant reductions in step time, stance phase, step length, andwidth during slip-like perturbations across age groups [31], though aging did not affect intra-limb coordination. [PERSON], et al. [32] showed older subjects had longer recovery times and steps, indicating greater destabilization. [PERSON], et al. [33] highlighted the critical role of the CoP mechanism in adjusting the CoM acceleration post-perturbation, particularly during the initial stages in young subjects. [PERSON], et al. [34] observed young participants took shorter, wider steps after a perturbation warning, with significant gait adjustments. [PERSON], et al. [35] found balance recovery involved a few corrective steps with larger hip and knee moments across young adults. [PERSON], et al. [36] noted that slower walking velocities resulted in more backward or wide corrective steps presented by the young. [PERSON], et al. [37] reported that earlier perturbations led to longer and wider recovery steps. [PERSON], et al. [4] detailed significant impacts on gait parameters, especially knee extension and flexion torques, depending on the gait cycle phase in young women. Three studies examined the trip-like effect of treadmill belt deceleration. [PERSON], et al. [38] found that for the elderly, barefoot walking increased stability during trip-like perturbations and significantly decreased walking speed compared to wearing shoes. [PERSON], et al. [19] noted increased positive and negative leg work during trip recovery, with the knee contributing significantly to negative work and the hip to positive work for the young. [PERSON], et al. [39] emphasized the importance of ankle proprioception and whole-body feedback in slip perception among young individuals. Six studies investigated the combined effects of acceleration and deceleration of one treadmill belt in the AP direction, focusing on neuromuscular responses and gait compensatory mechanisms. [PERSON], et al. [40] found significantly higher muscle activity, especially in ventral muscles, with rapid neuromuscular responses among young adults. [PERSON], et al. [41] reported faster compensatory reactions to slip-related perturbations, increasing trunk, arm, and CoM movements, and higher muscle activity in key leg muscles of young participants. [PERSON], et al. [42] showed that slipping and tripping increased step width and joint moments, using ankle and hip strategies for compensation. Also, despite the fact that aging did not alter overall gait, it affected hip extension moments during slipping. Another study by [PERSON], et al. [43] found that patients with knee osteoarthritis (KOA) had lower step lengths and gait speeds, indicating higher fall risk during backward slips compared to healthy older adults. [PERSON], et al. [44] showed that for young adults, trips were more destabilizing than slips, requiring significant adjustments in recovery steps and whole-body angular momentum. [PERSON] and [PERSON] [2] noted that CoM displacement regularity of young women varied with perturbation type and phase, with specific patterns in both AP and ML directions. These studies highlight the varied effects of perturbations on gait stability and the complex compensatory mechanisms needed during split-belt treadmill walking. In summary, the observed disturbances, such as slip-like and trip-like perturbations, had varying impacts depending on the sample population. Healthy young adults quickly adapted their gait to regain stability, while older adults and those with neurological impairments exhibited less efficient compensatory strategies, such as increased muscular co-contraction.