Core Temperature in Professional Football Players during practice

Abstract

0369 Heat related deaths have been documented in football players at all levels of competition. Ingestible temperature sensors now allow accurate measurements of core temperature (Tc) in these athletes while they participate in football activity. Core temperatures of professional players in the National Football League (NFL) while they participate in football practice have never been reported. PURPOSE: To measure the rise in Tc during practice in professional football players and compare the Tc of larger interior lineman (LM) to those of backs and receivers (BKS). METHODS: Eight LM, age = 26.5 ± 2 yr, height = 191.8 ± 4.5 cm, body weight (BW) = 134.8 ± 10.7 kg and body surface area (BSA) = 2.61 ± 0.12 m2 and six BKS (wide receivers, half backs, defensive backs, tight ends) age = 27 ± 4.2 yr, height = 185 ± 6.3 cm, BW = 95.6 ± 11.1 kg and BSA = 2.19 ± 0.16 m2 participated in the study. All players were NFL first or second team veterans. Subjects ingested a sensor at 11:00 PM prior to the day of data collection during pre-season training camp in July. Resting Tc were recorded in an air-conditioned area 1 h prior to the morning practice. Tc was then recorded in each player approximately every 15 min during two hours of football practice in full equipment. The practice consisted of three distinct periods including individual drills, 7 on 7 team and live scrimmage. Tc was also measured during the afternoon practice in shells. BW was recorded before and after practices for determination of percent dehydration. Changes in Tc over time were analyzed using repeated measures ANOVA and group differences in Tc and percent dehydration were analyzed using independent t-tests. RESULTS: The highest wet bulb temperatures were 22.8°C and 20.6°C during the morning and afternoon practices, respectively. Height (p < 0.05), BW (p < 0.0001) and BSA (p < 0.001) were all higher in LM compared to BKS. A significant linear trend was found for Tc in both groups, p < 0.0001. During the AM practice Tc rose from 37.07 ± 0.13 °C to 38.81 ± 0.48 °C in LM and 36.99 ± 0.09 °C to 38.36 ± 0.44 °C in BKS. When the highest two Tc recorded in each subject were compared, Tc were higher in LM (38.65 ± 0.48 °C, range = 37.47 to 39.29 °C) than BKS (38.44 ± 0.32 °C, range = 37.81 to 39.08 °C). As measured by change in BW during practice the LM were less dehydrated compared to BKS (−0.94 ± 0.6 % versus −1.3 ± 0.7 %), p < 0.05. CONCLUSIONS: NFL LM reached higher Tc during football practice compared to smaller BKS. The highest Tc in all subjects were generally obtained during live scrimmaging. Level of dehydration as measured by BW loss was not associated with Tc. LM had higher Tc but were less dehydrated compared to BKS. Supported by a faculty development grant from West Chester University.