Sweat and Sodium Losses in Professional Ice Hockey Players during a Pre-Season Practice and a Game

Abstract

Many players in the National Hockey League (NHL) are larger than the average-sized athlete. Additionally, they exercise in a micro-environment allowing only the face to be exposed for the evaporation of sweat. The combination of a large body surface area (BSA) and equipment may result in high sweat rates (SwR), sweat losses and sodium (Na+) losses. Replacing large daily sweat losses with hypotonic fluids may predispose these athletes to sodium dilution. PURPOSE: To measure SwR, sweat sodium content and total sodium losses in NHL players during a pre-season practice and compare these data to a pre-season game. METHODS: Ten players consisting of 4 defensemen and 6 line players (age = 27.7 ± 5.7 yr, ht = 188.7 ± 5.8 cm, mass = 96.7 ± 8.5 kg and BSA = 2.24 ± 0.12 m2) participated in the study. Sweat was collected during one of the first pre-season practices and then in a pre-season game the following week. Prior to the practice and game the skin of the right upper forearm of each player was scrubbed what alcohol, washed thoroughly with deionized water and dried with sterile gauze. A sweat patch was applied and secured with impermeable tape. Subjects recorded nude body weights (mass) before and after the practice/game and voided their bladder completely post practice/game for volumetric measurements. SwtR was calculated as change in mass adjusted for fluids consumed and urine produced during the practice and game. All players drank water and/or sports drinks only from their pre-measured and pre-labeled containers. Ambient temperature and wet bulb globe temperatures (WBGT) were recorded inside each arena next to the players' bench. Correlated t-tests were used for statistical analysis. RESULTS: WBG and ambient temperatures were higher during the game (14 and 17.7 °C) versus the practice (10.7 and 12.7 °C). SwR were not different between the practice (1.3 ±.29 1·hr−1) and game (1.22 ±.29 1 hr−1) but gross sweat losses were higher in the game (3.7 ±0.9 l versus 2.6 ±0.6 l). Players consumed more fluids during the game, 2981 ±1010 ml versus 1623 ± 272.7 ml but were not more dehydrated 1.5 ± .66% (game) and 1.2 ± .5% (practice). Sweat sodium was not different between the practice (60.9 ±31 mmol· 1−1 and game (67.4 ±20.5 mmol ·1−1) but players experienced greater total sodium losses in the game (251.5 ± 104 versus 167.6 ±117.6 mmol). CONCLUSIONS: Professional ice hockey players experience greater sweat and sodium losses during games compared to practices. Sodium supplementation may be necessary due to high sodium losses. This could have important implications particularly during post-season playoffs.