title: The Diurnal Variation on Cardiovascular Endurance Performance of Secondary School Athlete Student.
abstract: BACKGROUND
  The previous investigations in diurnal variation of endurance sports performance did not reach a consensus and have been limited. This study would be a valuable resource for endurance sports trainers and event managers to plan their training and competition in a specific time of day.
  
  
  OBJECTIVE
  The aim of this study is to find out the diurnal variation in cardiovascular endurance performance in the young athletes.
  
  
  METHODS
  Thirty five athlete students (15.17 ± 1.62 years) participated in this study. Maximal oxygen uptake (VO2max), post-exercise percentage of maximal heart rate (MHR% post-ex), post-exercise body temperature (BTemppost-ex), and post exercise blood lactic acid level (LApost-ex) were measured in this study. Three non-consecutive testings: A) Morning (09:00-10:00; AM), B) Noon (12:00-13:00; NN) and C) Afternoon (16:00-17:00; PM) were conducted. Participants were required to follow the meal plan and resting schedule for all testing days.
  
  
  RESULTS
  VO2max was significantly higher at NN (F2. 68 = 3.29, P < 0.05, η2 = 0.088) in comparison with PM. The MHR%post-ex, BTemppost-ex, LApost-ex was not significantly different among three times of day.
  
  
  CONCLUSIONS
  Diurnal effect on endurance performance was found and the highest exercise VO2max was identified at noon. Secondary school students or young athletes are recommended to have sports training related to VO2max at noon for the purpose of maximizing training effectiveness.
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Chun-Yip
authors.initials: CY
authors.lastname: Chin
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong ; Institute of Human Performance, University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Gary Chi-Ching
authors.initials: GC
authors.lastname: Chow
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Kwong-Chung
authors.initials: KC
authors.lastname: Hung
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Lik-Hang
authors.initials: LH
authors.lastname: Kam
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Ka-Chun
authors.initials: KC
authors.lastname: Chan
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Yuen-Ting
authors.initials: YT
authors.lastname: Mok
authors.affiliation: Unit of Associate Degree Studies, Faculty of Liberal Arts and Social Sciences,The Hong Kong Institute of Education, Tai Po, Hong Kong.
authors.forename: Nga-Mei
authors.initials: NM
authors.lastname: Cheng
keywords: Aerobic Exercise; Athlete; Circadian Rhythm; Diurnal Effect; Oxygen; Students