# Perturbations During Gait on a Split-Belt Treadmill: A Scoping Review
## 3 Results
### Perturbations in the Mediolateral (ML) Direction
#### 3.2.4 Summary of Results and Measurement Outcomes  
The studies from Table 2 examined the effects of gait perturbations in the ML direction combined with AP perturbations, revealing several common findings and significant differences.  
Across various studies, it was commonly observed that perturbations significantly impact gait stability. [PERSON], et al. [46] reported greater ranges and variability in angular momentum during platform oscillations, especially in amputees. Similarly, [PERSON], et al. [47] observed increased step width and gluteus medius muscle activity during different gait phases in young subjects. [PERSON], et al. [48] found that young adults increase the total spectral power of lower extremity muscles immediately following a perturbation, indicating distinct muscle fiber recruitment patterns during different gait phases. This suggests that muscle activity rapidly adapts to maintain stability. [PERSON] and [PERSON] [49] demonstratedfor the young greater local instability and variability in gait parameters under perturbations. [PERSON], et al. [50] noted that participants took faster, wider, and longer steps during perturbations, with older individuals walking faster than younger ones and displaying increased variability in gait kinematics. [PERSON], et al. [51] indicated that wider steps were associated with decreased balance control, increased GM activity, and reliance on a lateral ankle strategy to maintain balance without changes in the plantar flexion moment during perturbed walking in young participants.  
When examining ML shifts and AP direction changes, [PERSON], et al. [52] found that post-stroke individuals who experienced falls had shorter step durations and lengths during steady-paced walking and responded to ML perturbations with faster reactions and shorter initial steps. [PERSON] and [PERSON] [53] showed a significant improvement in the control of the CoM during quiet standing post-perturbation in young adults after training. [PERSON], et al. [9] measured the perturbation effect by changes in the MoS over six steps after perturbation. Contra-lateral sway and deceleration caused the largest ML and AP perturbation effects. Participants increased their MoS with wider, shorter, and faster steps, showing a common adaptive strategy. Changes were similar for both the elderly and the young. [PERSON], et al. [54] found that assistance from an active pelvis orthosis was helpful for recovery balance in the sagittal plane but not in the frontal plane for older participants. [PERSON], et al. [55] reported improved balance recovery after AP and ML perturbations immediately and one-week post-intervention of older participants. [PERSON], et al. [56] developed an algorithm to determine total recovery time, finding that older and younger individuals rapidly returned to stable walking post-perturbation.  
The last three studies from Table 2 focused on the effects of ML shifts, AP acceleration/deceleration of one belt, and tilt perturbations on gait and balance. [PERSON], et al. [57] observed decreased step time, stance phase percentage, and hip/knee range of motion, with increased ankle joint motion on both the perturbed and non-perturbed sides in young adults. [PERSON], et al. [58] found that young participants responded to perturbations by increasing step width and decreasing step length, especially during frontal plane oscillations. Surface rotations had the greatest impact on gait parameters, suggesting that young, healthy adults use lateral steps to maintain balance during perturbations. Lastly, [PERSON], et al. [59] reported that perturbation-based balance training for the elderly did not significantly differ from usual care in improving balance control or reducing fear of falling.