Symmetry of lower limb loading in healthy adults during normal and abnormal stance.

Purpose: The purpose of the research was twofold: (1) to describe the normal asymmetry in lower limb loading during a normal stance and during a stance with visual and vestibular disturbance relating to the lower limb dominance, (2) to assess relations of loading of both lower limbs with body weight and height (BMI) and leg functional dominance.

Methods: The subjects of this study were 95 students. Settings of the two Kistler platforms were used to register the time series of the vertical component of the ground reaction force while the subject was standing (45 seconds) in a normal position and next with eyes covered with a band and head tilted back position with one leg placed on one platform and the other on the second platform. The symmetry index (SI) was used to describe the asymmetry of the left or right loading.

Results: The greater loading of the left or right leg during standing was independent of the functional leg dominance. The distribution of left and right lower limb loading in both trials may suggest that a low asymmetry, less than 5%, is represented by about 30% of subjects in general. No significant correlation was found between the SI and BMI of subjects who had a normal body weight, but in the group of overweight subjects the correlation was very high (r = 0.9).

Conclusion: The results show that in describing norms of asymmetry in posture control in healthy humans it is very important to compare the results to posture asymmetry in various injuries or diseases. The most important result is that the higher asymmetry of lower limb loading is associated with overweight, which implies greater risk to health of those people.