Abstract: Objective To investigate the effect of different head flexion/extension angles on static sitting balance in normal youth. Methods34 selected healthy college students were measured with the track length of the centre of gravity under eyes closed, head in a neutral position,flexed in 15°, 30°, 45°, and extended in 15°, 30° (30 s each position). Results the average length from small to big were: head flexedin 30°, neutral position, flexed in 15°, flexed in 45°, extended in 15°, extended in 30°. There was no significant difference among the averagelength when head flexed in 30°, in neutral position and flexed in 15° (P>0.05). Conclusion The static sitting balance is the most whenhead put in neutral position to flexed in 30°, and worst in extended in 30° in healthy youth.

Key words: static sitting balance, head flexion/extension angle, normal youth, track length of the centre of gravity