تاثیر ارتفاع ساق‌کفش برنسبت هم‌انقباضی منتخبی از عضلات اندام تحتانی ورزشکاران مرد با و بدون ناپایداری مزمن مچ‌پا در حین اجرای آزمون‌های تعادلی

Background and Purpose
Lateral ankle sprains are the most common type of ankle injury, accounting for approximately 75% of all acute ankle injuries
These injuries typically result from sudden, excessive inversion, internal rotation, and plantar flexion, placing significant stress on the lateral ligaments of the ankle. When left untreated or improperly managed, lateral ankle sprains can progress to chronic ankle instability (CAI), a condition characterized by proprioceptive deficits, muscle weakness, delayed neuromuscular activation, and impaired static and dynamic balance. CAI not only increases the risk of recurrent sprains but also hinders athletic performance and daily function.
While considerable research has examined the effects of footwear design—such as sole and heel construction—on ankle biomechanics and stability in individuals with CAI, the specific impact of shoe collar height on muscle co-contraction and neuromuscular control during balance tasks remains understudied
Understanding how shoe collar height influences muscle activation patterns may inform footwear recommendations and injury prevention strategies for athletes with and without CAI. This study aimed to investigate the effect of shoe collar height on the co-contraction ratio of selected lower limb muscles during balance tests in male athletes with and without CAI.
 Methods
A total of twenty-eight male athletes (14 with CAI and 14 without CAI) participated in this controlled laboratory study. CAI was diagnosed using the Cumberland Ankle Instability Tool, ensuring a standardized approach to participant classification. Electromyographic (EMG) activity was recorded for eight lower limb muscles: tibialis anterior, peroneus longus, gastrocnemius medialis, gastrocnemius lateralis, soleus, vastus medialis, vastus lateralis, and biceps femoris. Each participant completed single-leg stance and Y balance tests under three conditions: barefoot, short-collar shoes, and high-collar shoes. The order of test conditions was randomized to minimize order effects.
Muscle co-contraction ratios were calculated to assess the simultaneous activation of agonist and antagonist muscle groups during balance tasks. This metric provides insight into joint stability and the neuromuscular strategies employed to maintain postural control. Data were analyzed for differences between footwear conditions and between groups (CAI vs. non-CAI).
Results
Shoe collar height significantly influenced the co-contraction ratio during the single-leg stance test (p < 0.05)
Post-hoc analysis revealed that the co-contraction ratio was highest in the barefoot condition, followed by short-collar shoes, and lowest in high-collar shoes. This suggests that high-collar shoes may provide external support, reducing the need for intense muscle co-contraction to stabilize the ankle. However, no significant differences were observed between the CAI and non-CAI groups (p = 0.57), indicating that the effect of collar height on muscle activation patterns was similar regardless of ankle stability status.
During the Y balance test, shoe collar height also significantly affected the co-contraction ratio (p = 0.001), with the highest ratios observed in the posterolateral direction, followed by the anterior and posteromedial directions. Again, no significant group differences were found (p = 0.31). These findings are consistent with prior research demonstrating that footwear with increased collar height can restrict ankle range of motion (ROM) and enhance mechanical support, thereby improving dynamic stability and reducing the muscular effort required for postural control
 Discussion
Proper balance control relies on the integrated function of the sensory-motor system, with somatosensory input—particularly proprioception—playing a central role in maintaining joint stability. Proprioceptive feedback from the ankle and surrounding musculature is critical for activating appropriate balance responses, both locally and through compensatory strategies involving proximal muscles such as those of the thigh. The present study’s findings align with the notion that external support provided by high-collar shoes can reduce the neuromuscular demand on lower limb muscles during balance tasks.
Supporting evidence from recent systematic reviews and meta-analyses indicates that high-top or high-collar shoes significantly reduce ankle injury rates and enhance joint mechanics compared to mid- or low-top designs. High-collar shoes provide structural support that counteracts inversion forces, a primary mechanism of lateral ankle sprain, and improve stability indices during dynamic tasks. Biomechanical studies have shown that high-collar footwear decreases ankle dorsiflexion and inversion ROM during landing and jump tasks, increases ankle joint stiffness, and improves medial-lateral stability. However, excessive restriction of motion or increased footwear mass could potentially alter muscle activation patterns or shift mechanical stress to adjacent joints, warranting further investigation.
The present study also found that barefoot conditions elicited the highest co-contraction ratios, likely reflecting the increased neuromuscular demand for joint stabilization in the absence of external support. This is in line with prior research showing that shoes and orthoses can accelerate muscle activation onset times and reduce the amplitude of muscle activity required for stability in individuals with CAI
Conclusion
Shoe collar height significantly impacts muscle co-contraction ratios during balance tests, with high-collar shoes reducing the need for intense muscle activation compared to short-collar shoes and barefoot conditions. This reduction in co-contraction may decrease fatigue and injury risk during training and competition, particularly for athletes with CAI. The findings suggest that high-collar shoes could be beneficial in both preventive and rehabilitative contexts for individuals at risk of ankle instability. However, the absence of significant differences between CAI and non-CAI groups indicates that the mechanical support provided by collar height is effective regardless of baseline ankle stability.
Future research should further explore the effects of shoe collar height during a broader range of functional activities, over longer durations, and in different athletic populations. Additionally, studies should investigate the interplay between footwear design, proprioceptive training, and intrinsic muscle strengthening to optimize both externally braced and intrinsic stabilization capacities
Article Message
Given that high-collar shoes reduced the co-contraction ratio during the single-leg stance and Y-balance tests, it is recommended that these types of shoes be used in training and competition to reduce fatigue and prevent sports injuries. Also, given that in this study, muscle electrical activity was measured during the single-leg stance and Y-balance tests, further research should be conducted during other functional activities, and results should be compared regarding muscle activity levels and sports performance (sports success).