title: Time-of-day effects on postural control and attentional capacities in children.
abstract: The present study aimed to examine the effect of time-of-day on postural control, body temperature, and attentional capacities in 5-6 year old children. Twelve male children (5-6-year-old) were asked to maintain an upright bipedal stance on a force platform with eyes open (EO) and eyes closed (EC) at 07:00, 10:00, 14:00, and 18:00 h. Postural control was evaluated by center of pressure (CoP) surface area (CoPArea), CoP mean velocity (CoPVm), length of the CoP displacement as a function of the surface (LFS) ratio and Romberg's index (RI). Oral temperature and the simple reaction time were also recorded at the beginning of each test session. The one way ANOVA (4 time-of-day) showed significant time-of-day effects on CoPArea (p<0.001), CoPVm (p<0.01), LFS ratio (p<0.001) and RI (p<0.01). Children's postural control was lower at 07:00 h and at 14:00 h in comparison with 10:00 h and 18:00 h. Likewise, the reaction time was significantly (p<0.001) better at 10:00 h and 18:00 h in comparison with 07:00 h and 14:00 h. Oral temperature was higher at 14:00 h and 18:00 h than 08:00 h and 10:00 h (p<0.001). In conclusion, the children's postural control fluctuates during the daytime (i.e., better postural control at 10:00 h and at 18:00 h) with a diurnal rhythm close to that of body temperature and attentional capacities. Therefore, the evaluation of changes in postural control of 5-6-year-old children using force plate measures is recommended in the middle morning or the late afternoon to avoid the post-awakening and the post-prandial phases.
authors.affiliation: Research Unit: Education, Motricity, Sports and Health, High Institute of Sport and Physical Education, Sfax, Sfax University, Tunisia; Faculty of Sciences of Bizerte, University of Carthage, Tunisia. Electronic address: baccoucherim@yahoo.fr.
authors.forename: Rym
authors.initials: R
authors.lastname: Baccouch
authors.affiliation: Research Laboratory: "Medical Imaging Technologies" (LR 12ES06, LTIM), Faculty of Medicine of Monastir, University of Monastir, Tunisia.
authors.forename: Nidhal
authors.initials: N
authors.lastname: Zarrouk
authors.affiliation: Research Laboratory: "Sports Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
authors.forename: Hamdi
authors.initials: H
authors.lastname: Chtourou
authors.affiliation: Research Unit: Education, Motricity, Sports and Health, High Institute of Sport and Physical Education, Sfax, Sfax University, Tunisia.
authors.forename: Haithem
authors.initials: H
authors.lastname: Rebai
authors.affiliation: Research Unit: Education, Motricity, Sports and Health, High Institute of Sport and Physical Education, Sfax, Sfax University, Tunisia.
authors.forename: Sonia
authors.initials: S
authors.lastname: Sahli
mesh_terms: D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000502:physiology; D006801:Humans; D008297:Male; D009055:Mouth / Q000502:physiology; D017440:Photoperiod; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology; D011312:Pressure; D011581:Psychological Tests; D011930:Reaction Time / Q000502:physiology
keywords: Attention; Children; Posture; Temperature; Time-of-day