Time of Day Influence on Postural Balance of Young and Older Men.

BACKGROUND: Many physiologic parameters fluctuate on a diurnal basis following the circadian rhythm function. The purpose of the study was to investigate if postural performance is interdependent of time of day and age. METHODS: 19 young (22.63 ± 3.43 y.o.) and 19 older male adults (60.21 ± 3.67 y.o.) performed three balance tests (quiet stance with open and closed eyes and bipedal balance on a Togu ball) at 12:00 AM and at 12:00 PM. Time and frequency domain variables of the center of pressure were analyzed. RESULTS: At eyes closed test, the younger had significant less distance traveled by the Center of Pressure (CoP) at night compared to day. At open eyes test, the younger had significant less CoP sway in the anterior-posterior (AP) axis at night compared to day. At Togu ball test the older showed increased peak-to-peak amplitude of CoP in both axes compared to younger. They also had lower frequency in the medial-lateral (ML) axis but higher in the AP axis compared to the younger. CONCLUSION: Younger seem to function better at night. There is also an indication that the older are better at day. The results on unstable surface indicate different control strategies between the two groups.