Context: Cooling the neck region can improve the ability to exercise in a hot environment. It might improve performance by dampening the perceived level of thermal strain, allowing individuals to override inhibitory signals.
Objective: To investigate whether the enhanced ability to exercise in a hot environment observed when cooling the neck region occurs because of dampening the perceived level of thermal strain experienced and the subsequent overriding of inhibitory signals.
Design: Crossover study.
Setting: Walk-in environmental chamber.
Patients or other participants: Eight endurance-trained, nonacclimated men (age = 26 ± 2 years, height = 1.79 ± 0.04 m, mass = 77.0 ± 6.2 kg, maximal oxygen uptake [V˙O(2max)] = 56.2 ± 9.2 mL·kg(-1)·min(-1)) participated.
Intervention(s): Participants completed 4 running tests at approximately 70% V˙O(2max) to volitional exhaustion: 2 familiarization trials followed by 2 experimental trials (cooling collar [CC] and no collar [NC]). Trials were separated by 7 days. Familiarization and NC trials were performed without a collar and used to assess the test variability.
Main outcome measure(s): Time to volitional exhaustion, heart rate, rectal temperature, neck skin temperature, rating of perceived exertion, thermal sensation, and feeling scale (pleasure/displeasure) were measured.
Results: Time to volitional exhaustion was increased by 13.5% ± 3.8% (CC = 43.15 ± 12.82 minutes, NC = 38.20 ± 11.70 minutes; t(7) = 9.923, P < .001) with the CC, which reduced mean neck skin temperature throughout the test (P < .001). Participants terminated exercise at identical levels of perceived exertion, thermal sensation, and feeling scale, but the CC enabled participants to tolerate higher rectal temperatures (CC = 39.61°C ± 0.45°C, NC = 39.18°C ± 0.7°C; t(7) = -3.217, P = .02) and heart rates (CC = 181 ± 6 beats/min, NC = 178 ± 9 beats/min; t(7) = -2.664, P = .03) at the point of termination.
Conclusions: Cooling the neck increased the time taken to reach volitional exhaustion by dampening the perceived levels of thermal strain.