Background and purpose: The effect of action observation on symmetry of weight distribution and stability indices in semi-dynamic stability in healthy older people is not identified yet. The aim of this study was to investigate the effect of action observation on the symmetry of weight distribution in lower limbs and stability indices in semi-dynamic stability among healthy non-athlete older people.

Materials and methods: An experimental study was performed in 72 healthy male and female volunteers aged 55 to 75 years old. The subjects were randomly divided into two groups of functional film observation and symbols. Demographic, clinical and laboratory information of the groups (lower extremity muscle strength, the vision, symmetry weight distribution, and dynamic stability indices) were collected and measured. Data was analyzed in SPSS V.16.

Results: Percentage of weight distribution showed no significant difference between the two groups. The comparison of changes between the two groups showed that observation of the film significantly improved total index (P =0.004), antero-posterior index (P =0.015), and medio-latral index (P =0.023) in stability of level 5. There was a significant improvement between the females of both groups in total, antero-posterior, and medio-latral balance index in stability of level 5 (P =0.001). The percentage changes of balance indices showed no significant differences among males.

Conclusion: The results showed that the action observation could have a positive effect on improvement of balance in healthy older people (especially in unstable levels). Significant improvement of stability indices in women after watching the film, may suggest greater sensitivity of women's mirror neurons.