MAXIMUM HEAT LOSS POTENTIAL IS LOWER IN FOOTBALL LINEMEN DURING AN NCAA SUMMER TRAINING CAMP BECAUSE OF LOWER SELF-GENERATED AIR FLOW

摘要

The purpose of this study was to compare the maximum potential for heat loss of football linemen (L) and non-linemen (NL) during a National Collegiate Athletic Association (NCAA) summer training camp. It was hypothesized that heat loss potential in L would be lower than NL because of differences in self-generated air flow during position-specific activities. Fourteen NCAA division 1 football players {7 L (mass: 126 +/- +/- kg; body surface area [BSA]: 2.51 +/- 0.19 m(2)) and 7 NL (mass: 88 +/- 13 kg; BSA: 2.09 +/- 0.18 m(2))} participated over +/- days in southern Florida (T-db: 31.2 +/- 1.6 degrees C, T-wb: 27.0 +/- 0.7 degrees C, T-r: 38.4 +/- 2.8 degrees C). Simultaneous on-field measurements of self-generated air velocities (v(self)) and mean skin temperatures (T-sk) were performed throughout practice, which included 4 drill categories (special teams, wind sprints, individual drills, and team drills). The resultant net potential for heat loss through convection, radiation, and evaporation (H-total) was calculated. Values for Tsk were similar between L and NL for all drills (L: 35.4 +/- 0.8 degrees C; NL: 35.4 +/- 0.4 degrees C; p = 0.92). However, v(self) was greater in NL during wind sprints, individual drills, and team drills (p <= 0.05). Consequently H-total) was significantly greater in NL for all drills except special teams (p <= 0.05). The mean estimated rate of oxygen consumption needed to exceed H-total) was 8.6 +/- 1.3 ml.kg(-1).min(-1) (2.5 +/- 0.4 METs) for NL but only 5.6 +/- 1.4 ml.kg(-1).min(-1) (1.6 +/- 0.4 METs) for L. A lower heat loss potential occurs in L because of the more static nature of their position-related activities and not because of differences in Tsk. The practical relevance of these findings is that potential interventions that increase convective and evaporative heat loss (i.e., mechanical fans) should specifically target L, particularly while they are participating in static on-field drills and during rest intervals.