title: Core temperature changes and sprint performance of elite female soccer players after a 15-minute warm-up in a hot-humid environment.
abstract: Warm-up session should be modified according to the environmental conditions. However, there is limited evidence regarding the proper soccer warm-up time for female players in the heat. The purpose of this study was to examine the rise in core body temperature and the sprint performance after a 15-minute warm-up in a hot-humid environment using female soccer players during the different phases of their menstrual cycle. Thirteen eumenorrheic national female soccer players (aged 18.8 ± 1.3 years, (Equation is included in full-text article.)53.05 ± 6.66 ml·kg·min) performed a 15-minute warm-up protocol at an ambient temperature of 32.5 ± 1.6° C with a relative humidity of 53.6 ± 10.2% during their early follicular and midluteal phases of their cycle. The warm-up protocol is composed of jogging, skipping by moving the legs in various directions, and sprinting alternated with jogging, followed by a 45-minute recovery period. Rectal temperatures were recorded during the rest period and every 5 minutes throughout the warm-up and recovery phases of the study. Heart rate was monitored at rest and every 5 minutes during the warm-up. Forty-yard sprint time was assessed immediately after the completion of warm-up, which was later compared with the time at baseline. The value for the baseline was obtained at least 2 days before the experiment. During the early follicular and midluteal phases, the rectal temperatures obtained at the end of the warm-up period were significantly (p < 0.05) higher by 1.26° C (95% confidence interval [CI] = +0.46 to +2.06° C) and 1.18° C (95% CI = +0.53 to +1.83° C), whereas the heart rates increased to 153.67 ± 20.34 and 158.38 ± 15.19 b·min, respectively. After 20 minutes of the recovery period, the rectal temperature decreased by approximately 50%. The sprint times were significantly (p < 0.05) faster post-warm-up during both the early follicular (5.52 seconds; 95% CI = 5.43-5.60 seconds) and midluteal phases (5.51 seconds; 95% CI = 5.41-5.60 seconds) compared with the baseline time (5.66 seconds; 95% CI = 5.58-5.74 seconds). There were no significant differences in any parameters assessed after warm-up between the 2 phases. In conclusion, a 15-minute warm-up increased the core temperature by approximately 1° C and improved the 40-yd sprint time for elite female soccer players in a hot environment regardless of menstrual phase.
authors.affiliation: 1Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; and 2Sports Medicine Program, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Juraiporn
authors.initials: J
authors.lastname: Somboonwong
authors.forename: Ladawan
authors.initials: L
authors.lastname: Chutimakul
authors.forename: Sompol
authors.initials: S
authors.lastname: Sanguanrungsirikul
mesh_terms: D000293:Adolescent; D054874:Athletic Performance / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007590:Jogging / Q000502:physiology; D008597:Menstrual Cycle / Q000502:physiology; D012420:Running / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D063996:Warm-Up Exercise / Q000502:physiology*; D055815:Young Adult