title: Effects of prolonged and reduced warm-ups on diurnal variation in body temperature and swim performance.
abstract: Previous studies have suggested a diurnal variation in the performance of physical tasks. The theoretical basis for the effect of time-of-day on performance centers on the circadian rhythms of many physiological variables and especially the body temperature curve. This investigation had two purposes: (a) to determine if increasing the volume of the warm-up could eliminate diurnal variation in body temperature and swim performance, and (b) to determine if reduction of the warm-up volume in the late afternoon would affect body temperature and swim performance. Participants for this investigation included 6 male and 4 female competitive swimmers (mean age = 15 +/- 1 years). Before the swim performance trials in the morning, participants warmed up with either standard volume (2,011.68 m) or 200% of that volume. Before the afternoon swim performance trials, warm-up volumes were either 33% or 100% of the standard warm-up volume. Before entering the water and immediately after the warm-up, temperature was taken from the ear. After the swim performance, participants were asked to rate their perceived exertion on the basis of Borg's CR-10 rating scale. The order of test administration for time of day and warm-up condition was balanced and with tests carried out over 4 days. Each swimmer completed 1 test condition (warm-up) per day. Results indicated that increased morning warm-up time eliminated diurnal variation in body temperature; however, evening superiority in swimming performance was not eliminated. The results also indicated that reducing the volume of the afternoon warm-up to 33% of the standard warm-up had no effect on body temperature or swim performance.
authors: Physical Education Program, University of Arizona, Tucson, Arizona 85721, USA. marnett@u.arizona.edu
authors: Mark G
authors: MG
authors: Arnett
mesh_terms: D000293:Adolescent; D001831:Body Temperature / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010806:Physical Education and Training / Q000379:methods; D005082:Physical Exertion / Q000502:physiology; D013550:Swimming / Q000502:physiology*; D013647:Task Performance and Analysis; D013997:Time Factors