# Lower Limb Joint Coordination and Coordination Variability During Landing: A Scoping Review
## 3 Results
### Training and Fatigue Interventions  
Dynamic coordination of the lower limbs during landing is not static; it can be altered through training interventions or acutely affected by fatigue. Several studies in the review addressed whether purposeful training or the presence of fatigue modulates joint coordination and variability, with implications for injury prevention programs and athletic conditioning. **Neuromuscular Training Effects:** Interventions such as balance training, plyometrics, or technique training may influence coordination patterns. In patients with chronic ankle instability, rehabilitation programs have aimed to restore more stable coordination. For example, a recent study evaluated the effects of a balance training program on joint coupling in CAI patients [40]. Before training, CAI individuals showed the aforementioned high coupling variability and atypical shank-foot coordination. After a period of targeted neuromuscular training (using unstable surfaces and exercises to challenge ankle control), the participants demonstrated reduced variability in joint coupling (approaching the consistency seen in healthy individuals) and more symmetric coordination between lower limb segments. Another quasi-intervention explored in the literature is equipment modification. A study by [PERSON] et al. examined how changing shoe inside stiffness affected coordination in male and female athletes during landing [23]. While the primary finding was related to gender (females initially had lower coupling variability than males; see Section 3.4), it also showed that adding cushioning (soft or stiff insoles) did not significantly change coordination patterns or variability overall (\(p\) > 0.05). In other words, simply altering shoe insole properties did not perturb the coordination strategy of landing in a consistent way. However, one interesting outcome was that with insoles (regardless of stiffness), female athletes were able to achieve similar coupling variability as males. This could imply that a more comfortable or supported landing surface (via insoles) might encourage females to utilize a slightly more varied movement strategy (increasing variability from their normally lower baseline to match males), or conversely, that the insoles provided no additional challenge so both sexes landed with their natural patterns. **Fatigue and Exhaustive Exercise:** Fatigue is known to degrade neuromuscular performance and has been hypothesized to alter coordination control. In landing tasks, fatigue (whether from repetitive jumps, running, or targeted muscle exhaustion) can lead to changes in joint kinematics and potentially coordination variability. [PERSON], [PERSON] [41] explored the combined effects of drop height and fatigue on landing mechanics in active females. They observed that higher drop heights and a fatigued state each independently tended to increase risky biomechanical features (such as greater knee valgus and ground reaction forces). While their study reported traditional kinetic/kinematic metrics, the implications for coordination can be inferred: as athletes fatigued, the fine-tuned timing between joints deteriorates, possibly increasing coordination variability or causing shifts to less favourable coordination patterns (including more reliance on passive structures as muscles tire). Another investigation specifically looked at the effect of isolated muscle fatigue on coordination: [PERSON], [PERSON] [42] induced hamstring fatigue and measured hip-knee joint coordination variability during a subsequent sidestep cutting manoeuvre. They found that hamstring fatigue led to significant changes in coordination variability--in that sidestep task, variability increased, indicating a loss of the usual coordination control once the hamstrings were weakened. A practical example of fatigue's impact is seen when comparing the first versus second landing in a drop jump sequence.