OBJECTIVES: The aim of this study was to investigate diurnal changes of the postural control in young women without and with hormonal contraceptive treatment.
METHODS: The postural activity was assessed during stance from two accelerometers positioned at the level of the lumbar (L5) and thoracic (Th4) vertebra in twenty healthy young women non-using (13) and using (7) hormonal contraception.
RESULTS: We observed a significant increase of trunk tilts in the morning in the group of women with hormonal contraception compared to control. Women with hormonal contraception showed the significant decrease of trunk tilts and their velocity in the evening in relation to increased morning data at the L5 in anterior-posterior direction during stance on foam. Measurements at Th4 showed higher variability of lateral trunk tilts in conditions with altered somatosensory inputs. Distinct reduction of velocity of lateral trunk tilts in the evening related to morning measurements were present in the control group at the L5 in conditions with altered somatosensory inputs and at the Th4 in all experimental conditions in both groups.
CONCLUSION: We demonstrated diurnal changes of the postural control in young women. Women using hormonal contraceptives showed a weakened postural stability compared with the control group in the morning and the normalization of postural stability in the evening to the values of the control group. These findings suggest that the time of day and the use of hormonal contraception affect postural stability of women.