title: The effect of training at a specific time-of-day on the diurnal variations of short-term exercise performances in 10- to 11-year-old boys.
abstract: The aim of this study was to assess the effect of time-of-day-specific training on the diurnal variations of short-term performances in boys. Twenty-four boys were randomized into a morning-training-group (07:00-08:00h; MTG), an evening-training-group (17:00-18:00h; ETG) and a control-group (CG). They performed four tests of strength and power (unilateral isometric maximal voluntary contraction of the knee extensor muscles, Squat-Jump, Counter-Movement-Jump and Wingate tests) at 07:00 and 17:00h just before (T0) and after 6 weeks of resistance training (T1). In T0, the results revealed that short-term performances improved and oral temperature increased significantly from morning to afternoon (amplitudes between 2.36 and 17.5% for both oral temperature and performances) for all subjects. In T1, the diurnal variations of performances were blunted in the MTG and persisted in the ETG and CG. Moreover, the training program increase muscle strength and power especially after training in the morning hours and the magnitude of gains was greater at the time-of-day-specific training than at other times. In conclusion, these results suggest that time-of-day-specific training increases the child's anaerobic performances specifically at this time-of-day. Moreover, the improvement of these performances was greater after morning than evening training.
authors.affiliation: Research Laboratory Sports Performance Optimization, National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
authors.forename: Hichem
authors.initials: H
authors.lastname: Souissi
authors.forename: Hamdi
authors.initials: H
authors.lastname: Chtourou
authors.forename: Anis
authors.initials: A
authors.lastname: Chaouachi
authors.forename: Mohamed
authors.initials: M
authors.lastname: Dogui
authors.forename: Karim
authors.initials: K
authors.lastname: Chamari
authors.forename: Nizar
authors.initials: N
authors.lastname: Souissi
authors.forename: Mohamed
authors.initials: M
authors.lastname: Amri
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D015992:Body Mass Index; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation*; D017079:Exercise Tolerance / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008019:Life Style; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D013647:Task Performance and Analysis; D013997:Time Factors; D014416:Tunisia