Physiological and Perceived Effects of Forearm or Head Cooling During Simulated Firefighting Activity and Rehabilitation.

CONTEXT:  Cooling devices aim to protect firefighters by attenuating a rise in body temperature. Devices for head cooling (HC) while firefighting and forearm cooling (FC) during rehabilitation (RHB) intervals are commonly marketed, but research regarding their efficacy is limited.

OBJECTIVE:  To investigate the physiological and perceived effects of HC and FC during firefighting drills and RHB.

DESIGN:  Randomized controlled clinical trial.

SETTING:  Firefighter training center.

PATIENTS OR OTHER PARTICIPANTS:  Twenty-seven male career firefighters (age = 39 ± 7 years; height = 169 ± 7 cm; weight = 95.4 ± 16.8 kg).

INTERVENTION(S):  Firefighters were randomly assigned to 1 condition: HC (n = 9), in which participants completed drills wearing a cold gel pack inside their helmet; FC (n = 8), in which participants sat on a collapsible chair with water-immersion arm troughs during RHB; or control (n = 10), in which participants used no cooling devices. Firefighters completed four 15-minute drills (D1-D4) wearing full bunker gear and breathing apparatus. Participants had a 15-min RHB after D2 (RHB1) and D4 (RHB2).

MAIN OUTCOME MEASURE(S):  Change (Δ) in gastrointestinal temperature (TGI), heart rate (HR), physiological strain index, and perceived thermal sensation.

RESULTS:  The TGI increased similarly in the HC and control groups, respectively (D1: 0.57°C ± 0.41°C, 0.73°C ± 0.30°C; D2: 0.92°C ± 0.28°C, 0.85°C ± 0.27°C; D3: -0.37°C ± 0.34°C, -0.01°C ± 0.72°C; D4: 0.25°C ± 0.42°C, 0.57°C ± 0.26°C; P > .05). The ΔHR, Δ physiological strain index, and Δ thermal sensation were similar between the HC and control groups during drills (P > .05). The FC group demonstrated a decreased TGI compared with the control group after RHB1 (-1.61°C ± 0.35°C versus -0.23°C ± 0.34°C; P < .001) and RHB2 (-1.40°C ± 0.38°C versus -0.38°C ± 0.24°C; P < .001). The physiological strain index score decreased in the FC group compared with the control group after RHB1 (-7.9 ± 1.3 versus -2.6 ± 1.7; P < .001) and RHB2 (-7.9 ± 1.6 versus -3.6 ± 1.1; P < .001), but no differences between groups were demonstrated for ΔHR or Δ thermal sensation (P > .05).

CONCLUSIONS:  The HC did not attenuate rises in physiological or perceptual variables during firefighting drills. The FC effectively reduced TGI and the physiological strain index score but not HR or thermal sensation during RHB. Clinicians and firefighters should not recommend the use of HC during firefighting but can consider using FC during RHB intervals in the field.