acceleration of upper trunk coordination in young versus old adults during walking on the level and irregular floor surface using mtx sensor

objectives: to evaluate the reliability of head and trunk acceleration measured by mtx sensors during walking on level and irregular surfaces and to compare the differences between healthy young and old adults. methods: participants were 20 young female university students and 20 non-faller elderly women in iran, 2013. two mtx sensors were used to measure head and trunk accelerations in the vertical (vt), anterior-posterior (ap), and medial-lateral (ml) directions while participants walked on a 7-meter walkway.  results: icc values in young group were higher as compared to non- faller elderly group; icc was greater than 0.7 for 89.47%(34.38) of variables in young group and for 60.52%(23.38) in non- faller. intersession reliability for upper trunk coordination indices in regular surface and in young group showed highest values as compared with other conditions in both groups, whereas the lowest intersession reliability was found in irregular floor surface indices in non-faller elderly group. discussion: the calculated icc, sem, cv%, mdc values suggest that the mtx sensors provide precise recordings and detect small changes in upper  trunk accelerometric parameters. icc values were influenced by the age and the floor condition. in healthy young, all icc values in regular surface were higher than 0.7. floor condition effect was noticeable in elderly especially in ml direction. during walking on irregular surface, ml acceleration, velocity and harmonic  ratio in elderly showed lower repeatability.