مقایسه تاثیر ارتفاع پاشنه بر روی شاخص‌های حفظ تعادل

    Background & Aim: Good balance is essential to do daily activities. Recent studies have focused on the adaptability of balance through previous experiences and training. Study of the balance of people who have had some kind of these experiences can clarify the nature of the adaptability of balance. The aim of the present study is to evaluate balance ability in persons who are exposed to balance perturbations during daily activities for a long time in order to confirm the effects and durability of balance training exercises that are important in rehabilitation. Patients and Method: This is a cross-sectional experimentalloid study conducted on 60 healthy subjects divided into 2 groups, each containing 30 adult women who were selected by simple random sampling and inclusive criteria. Group 1 had no experience of using high-heeled shoes during 6 months prior to the experiment and group 2 had the experience of continuous use of high-heeled shoes(more than 3 cm) for at least 6 months. Using Biodex Stability System, Overall Dynamic Stability Index(ODSI) and Overall Limits of Stability Index(OLSI) were recorded while the subjects were wearing shoes designed at three heel heights(0cm, +3cm, +5cm) in different trials. ODSI and OLSI were dependent variables that were compared in each group by repeated measurement test and between the groups by independent t-test. The data analysis was done by SPSS version 10. Results: In group 1, with increasing heel height to +5cm as compared with 0cm or +3cm, the ability of balance control decreased significantly(p<0.05), but in group 2, with increasing heel height, no significant difference was detected in the ability of balance control. Besides, the two groups were significantly different in terms of ODSI for +5cm heel height(p<0.05). Conclusion: Different biomechanical factors such as changing the position of ankle joint and neural factors such as dependency on feedback system could explain lack of rapid and suitable muscular responses and balance control with increasing heel height in the subjects of group 1. Although there were the same changes in heel height and biomechanical factors in group 2, it seems that the changes in neural factors which are due to the prolonged use of high-heeled shoes might be the reason for the difference between the two groups. Suitable anticipatory responses to control the balance with increasing heel height could explain the results in this group. There might be some kind of adaptation and learning in group 2 due to the prolonged use of high-heeled shoes. The findings support the adaptation in C.N.S and permanent changes in the strategies of balance control during daily motor activities.