EFFECTS OF PROLONGED AND REDUCED WARM-UPS ON DIURNAL VARIATION IN BODY TEMPERATURE AND SWIM PERFORMANCE

Studies previously conducted suggest a diurnal variation in the performance of physical tasks that may be in part a result of the body temperature curve (Atkinson & Reilly, 1977). This investigation had two purposes: 1) to determine if increasing the volume of the warm-up could eliminate diurnal variation in body temperature as reflected by tympanic temperature and swim performance, and 2) to determine if reduction of the warm up volume in the late afternoon would affect body temperature as reflected by tympanic 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, participants' warm-up was either normal or double the volume in the morning and normal or 33% of the volume in the afternoon. Before entering the water and immediately following warm-up, temperature was taken from the ear. Following the swim performance, participants were asked to rate their perceived exertion (RPE) based on 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 four days. Each swimmer completed one test condition (warm-up) per day. Results revealed a diurnal variation in body temperature between the normal morning warm-up and the afternoon warm-ups (p = .009), however the increased morning warm-up volume eliminated diurnal variation in body temperature (100% volume morning warm-up: 34.79°C ± 0.76; 200% volume morning warm-up: 35.61°C ± 0.72; 100% afternoon warm-up: 35.64°C ± 0.83; 33% volume afternoon warm-up: 35.51°C ± 0.55). Evening-superiority in swimming performance was not eliminated (100% volume morning warm-up: 57.38 s ± 4.77; 200% volume morning warm-up: 58.48 s ± 5.69; 100% afternoon warm-up: 56.88 s ± 5.09; 33% volume afternoon warm-up: 56.86 s ± 4.87; p = .017). The results also indicated that reducing the volume of the afternoon warm-up to 33% of the normal warm-up had no effect on body temperature or swim performance.