title: Morning versus evening power output and repeated-sprint ability.
abstract: We investigated the effect of time-of-day on both maximal sprint power and repeated-sprint ability (RSA). Nine volunteers (22+/-4 yrs) performed a RSA test both in the morning (07:00 to 09:00 h) and evening (17:00 to 19:00 h) on different days in a random order. The RSA cycle test consisted of five, 6 sec maximal sprints interspersed by 24 sec of passive recovery. Both blood lactate concentration and heart rate were higher in the evening than morning RSA (lactate values post exercise: 13+/-3 versus 11+/-3 mmol/L(-1), p<0.05). The peak power developed during the first sprint was higher in the evening than morning (958+/-112 vs. 915+/-133 W, p<0.05), but this difference was not apparent in subsequent sprints, leading to a higher power decrement across the 5x6 sec test in the evening (11+/-2 vs. 7+/-3%, p<0.05). Both the total work during the RSA cycle test and the power developed during bouts 2 to 5 failed to be influenced by time-of-day. This suggests that the beneficial effect of time-of-day may be limited to a single expression of muscular power and fails to advantage performance during repeated sprints.
authors.affiliation: Laboratoire ACTES, UPRES-EA 3596, UFR STAPS-U.A.G., Campus de Fouillole, Pointe-à-Pitre Cedex, Guadeloupe, France. racinais_seb@hotmail.com
authors.forename: Sébastien
authors.initials: S
authors.lastname: Racinais
authors.forename: Philippe
authors.initials: P
authors.lastname: Connes
authors.forename: David
authors.initials: D
authors.lastname: Bishop
authors.forename: Stephen
authors.initials: S
authors.lastname: Blonc
authors.forename: Olivier
authors.initials: O
authors.lastname: Hue
mesh_terms: D000328:Adult; D000339:Affect; D001143:Arousal; D001696:Biomechanical Phenomena; D002940:Circadian Rhythm; D005080:Exercise Test; D006801:Humans; D008297:Male; D009042:Motivation; D009043:Motor Activity / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012420:Running / Q000502:physiology*