Abstract
CONTEXT: Slips, trips, and falls are leading causes of musculoskeletal injuries in firefighters. Researchers have hypothesized that heat stress is the major contributing factor to these fireground injuries. OBJECTIVE: To examine the effect of environmental conditions, including hot and ambient temperatures, and exercise on functional and physiological outcome measures, including balance, rectal temperature, and perceived exertion. DESIGN: Randomized controlled clinical trial. SETTING: Laboratory environmental chamber. PATIENTS OR OTHER PARTICIPANTS: A total of 13 healthy, active career firefighters (age = 26 ± 6 years [range = 19-35 years], height = 178.61 ± 4.93 cm, mass = 86.56 ± 16.13 kg). INTERVENTION(S): Independent variables consisted of 3 conditions (exercise in heat [37.41°C], standing in heat [37.56°C], and exercise in ambient temperature [14.24°C]) and 3 data-collection times (preintervention, postintervention, and postrecovery). Each condition was separated from the others by at least 1 week and lasted a maximum of 40 minutes or until the participant reached volitional fatigue or a rectal temperature of 40.0°C. MAIN OUTCOME MEASURE(S): Firefighting-specific functional balance performance index, rectal temperature, and rating of perceived exertion. RESULTS: Exercise in the heat decreased functional balance, increased rectal temperature, and altered the perception of exertion compared with the other intervention conditions. CONCLUSIONS: A bout of exercise in a hot, humid environment increased rectal temperature in a similar way to that reported in the physically active population and negatively affected measures of functional balance. Rather than independently affecting balance, the factors of exercise and heat stress appeared to combine, leading to an increased likelihood of slips, trips, and falls.