Ice hockey is a contact sport played in a cold environment which leads to assumptions that players are not exposed to a thermal challenge. The purpose of this study was to test the hypothesis that the wearing of hockey protective equipment during an exercise protocol designed to simulate a hockey game would induce a thermal challenge and lead to decrements in performance. In order to test this hypothesis and qualify the physiological responses, subjects performed a standardized protocol performed on a stationary cycle ergometer in an environmental chamber set at typical (12ºC) ice hockey ambient conditions. The simulation was performed twice; once while wearing cotton undergarments only (NP), and once while wearing cotton undergarments and the typical protective equipment worn during a hockey game (P). Work intensity during each trial was held constant and was evaluated by examining mean power output, which was similar under both P and NP conditions (348.2 W vs 352.08 W, P > 0.05) P vs NP, respectively. Body (37.18 ºC vs 36.58 ºC) and skin temperatures (34.12 ºC vs 28.85 ºC) were elevated in P vs NP, respectively (P<0.05). Core temperatures (37.50 ºC vs 37.41ºC) displayed a trend towards being higher in P vs NP particularly during the third period of simulation (P = 0.053). Sweat loss as a percent of body mass was greater in P vs NP (2.57% vs 1.18%, respectively P<0.05), which led to an increase in plasma osmolality (287 vs 283 mosmol/kg H2O, respectively P<0.05) working heart rate (83.7% vs 78.8% of maximum heart rate), resting heart rate (63.4% and 55.9% of maximum heart rate), and urine specific gravity (1.026 vs 1.017) for P vs NP respectively (each P<0.05). The drop-off in power from pre to post simulated game was examined in both conditions by the use of five repeated maximal six second sprints interspersed with 24 seconds of recovery. The drop-off in both peak (12.0% vs 0.2%) and mean power (14.5% vs 2.7%) was greater in P versus NP (P<0.05). Plasma lactate concentration was higher following the simulated game in P vs NP (9.64 vs 5.96 mmol/L, P<0.05) as was plasma norepinephrine (2274.0 vs 1366.9 pg/ml, P<0.05). Rating of Perceived Exertion increased by 30-53% in the P condition (P<0.05) even though power outputs were equivalent. The elevated body temperature and increased water loss appeared to increase glycolytic flux, which when coupled with the consequences of thermal stress, reduced power output and led to the perception of elevated work intensities during the simulated game.