[Postural control depends on testing situation].

INTRODUCTION

Most often postural control is evaluated in posturography, i. e. in a static testing condition. The aim of this study was to evaluate correlations and differences between posturography and dynamic testing situations to get information about the informative value of static testing situations on dynamic conditions.

METHODS

40 healthy subjects participated in this study (m=23; w=17; age: 23.8±2.9 years; height: 177.0±8.5 cm; weight: 71.5±10.5 kg). Subjects were tested on their ability to maintain postural stability on a force platform (posturography, static condition) and on a movable and instable plate (dynamic condition). Furthermore, we analyzed balance correcting responses to a standardised disturbance of postural stability. EMG-activity was recorded of the following muscles: m. tibialis anterior, m. gastrocnemius lateralis, m. vastus lateralis, m. biceps femoris, and m. erector spinae. Pearson's Correlations were used to examine the relationship between postural control in static and in dynamic testing situations. Student's t-tests were used to examine differences in several parameters between static and dynamic testing situations.

RESULTS

Comparisons of postural control in static and in dynamic conditions lead to marginal correlations between performances in these test situations (r=-0.02 to r=0.45). Moreover, EMGactivity showed changes concerning quantitative parameters and coordination patterns.

DISCUSSION

Regarding correlations and analyses of EMG-activity we hypothesised different postural control strategies depending on each testing situation. Therefore, postural control seems not to be a generalizable ability. These data suggest that there is doubt on the use of posturography in static condition to predict performance in dynamic situations that could induce falls in elderly people or injuries in athletes. It appears comprehensible that dynamic testing situations are more suitable.