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Opinions expressed in the Sports Performance Blog are the authors’. They do not necessarily reflect positions of ACSM.

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  • Active Voice: Does Drink Temperature Matter?

    by Guest Blogger | Dec 14, 2015

    By Dallon Lamarche, B.SC., and Glen P. Kenny, Ph.D.

    Dallon Lamarche, B.SC. Glen P. Kenny, Ph.D.

    Hydration is of particular importance for everyone participating in exercise and/or work-related tasks. This is especially relevant in hot environments when the body will store excess heat. Recently, researchers have considered whether the temperature of ingested water could play a factor in regulating the amount of heat stored and thereby alter core body temperature. Prior to our publication in the June 2015 issue of MSSE, the media has outlined that consuming hot water resulted in a lower amount of heat stored in the body compared to cold waterdue to an over-compensatory increase in sweating. This counterintuitive notion was based on a recent study which suggested that hot water may help cool the body. However, our recent findings show that ingesting hot or cold water does not influence body heat storage, and thus core temperature regulation during exercise. 

    In our study, 10 males (19-32 years) cycled for 75 minutes at normal room temperature (25°C) at 50 percent of their maximal oxygen uptake. The exercise was performed in the Snellen whole-body direct calorimeter, which is a device that precisely measures the amount of heat lost over time (through sweat evaporation and dry heat exchange). During exercise, participants consumed either hot (50°C) or cold (1.5°C) water every 15 minutes. We observed a continuous separation in whole-body sweating such that sweating was higher with hot relative to cold water ingestion. However, this difference in sweating was proportionate to the difference in heat content of the ingested water between the temperature conditions, resulting in similar changes in body heat storage. Therefore, we showed that, during moderate prolonged exercise, the human body adjusts the sweating response to compensate for the heat content of the ingested water—no less and no more—such that heat balance is maintained. 

    Our findings indicate that the temperature of ingested water does not have a direct influence on body temperature during exercise. However, one cannot ignore the different behavioral and psychological effects that water of different temperatures may have on maintaining adequate hydration. For instance, the palatability of cold water is shown to clearly be more favorable during prolonged exercise in comparison to hot water. When provided the option to drink cold water at will in one session and hot water in another, a group of investigators demonstrated several years ago that individuals will ingest much more cold water (by about 37 percent). This has important implications for the athlete and the worker because individuals are more inclined to drink cold water during physical activity which leads to a better maintenance of hydration and core body temperature regulation. In addition, cold water ingestion has been shown to improve performance, as evidenced by extended time to exhaustion and lower perceived exertion in performance based events when compared to ingesting hot water. On the other hand, drinking hot water during exercise is not pleasant as anecdotally reported by the participants in our study and, consequently, may hinder performance through behavioral and psychological modifications. 

    Ultimately, our message is clear: athletes and workers should consume water at cooler (or “more comfortable”) temperatures during physical tasks as opportunities allow. In the end, the consumption of water itself is the most important consideration for hydration status.

    Viewpoints presented on the ACSM blog reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM. 

    Dallon Lamarche is a recent bachelor of science graduate with specialization in human kinetics at the University of Ottawa, Canada. He completed the study highlighted in this commentary at the Human and Environmental Physiology Research Unit as part of his senior year research project requirements under the supervision of Dr. Glen P. Kenny. 

    Glen P. Kenny is a professor of exercise physiology at the University of Ottawa, holds a university research chair in environmental physiology and is a member of ACSM. His research has been directed at characterizing the physiological control mechanisms governing human temperature regulation during heat stress. An area of special focus in his work is the investigation of the physiological effects of heat stress in subpopulations with conditions rendering them particularly vulnerable to heat injury, such as aging, obesity and diabetes. 

    This commentary presents Mr. Lamarche’s and Dr. Kenny’s views on the topic related to a study which they and colleagues recently completed. Their research report appears in the June 2015 issue of
     Medicine & Science in Sports & Exercise® (MSSE)

  • From seed to forest, EIM is positively impacting lives

    by Guest Blogger | Dec 14, 2015

    By Adrian Hutber, PhD, Vice President of Exercise is Medicine

    Exercise is Medicine (EIM) began as a seed of an idea just over eight years ago. As part of a presidential legacy program, ACSM leadership, together with incoming President Ron Davis of the American Medical Association, developed a vision for a global health initiative that would facilitate physical activity as a chronic disease health intervention through physician-patient interactions. Further, EIM would work with the medical community, health systems and exercise professionals to expand the breadth of these interventions by incorporating physical activity into treatment plans.

    The seed took root in December 2007 at the National Press Club when EIM was formally announced, and the initiative has been growing ever since. Consider:

    • EIM is now in more than 40 countries
    • More than 6,000 physicians have been trained
    • 9,000 exercise professionals have been trained to receive patient referrals
    • EIM has been promoted in the Wall Street Journal
    • The EIM Global Research Center has been established in partnership with Emory University to track progress and gain insights for continuous improvement
    • Early in 2016, the first major health system will launch using all the major components of the EIM Solution

    How has so much been done so fast? It took a solid vision that aligns with ACSM’s mission, a passionate advisory board and support staff, and a number of corporate partners who understood the value of promoting physical activity as a means for combatting chronic disease. Soon after the announcement at the National Press Club, ACSM began the process of identifying sponsors who could help fund the implementation of the EIM plan. Over the last eight years, several organizations have provided their support to EIM, including companies representing the fitness, health care, medical equipment, food and beverage, and personal hygiene industries. As is our practice, all of these relationships are transparent and allow total independence in the expansion of physical activity and health worldwide. We’re grateful for this cross-industry collaboration that fertilized that initial seed and helped it grow into a forest of healthy interventions all around the world.

    At the end of the day, it’s about impacting lives. Here are some quotes from real people whose lives were changed through the principals of EIM:

    • “The EIM program has helped motivate me to start exercising regularly.”

         -Samantha, age 31

    • “I just had a call from my doctor after last Friday’s physical. My weight is down, I have been declared free of pre-diabetes and for the first time in 10 years all my cholesterol numbers are as they should be. My blood pressure is 107/71 and I’m coming off the medication, whoo hoo!”

         -Richard, age 60

    • “EIM has completely changed my life. You know what to do to improve your health because a trained professional is now in your corner helping you every step of the way. 

         -Lynn, age 62

    • “The program has been a great resource for my patients. The guidance the program provides gives my patients the confidence to exercise. They have improved their exercise tolerance, feeling of well-being, weight and blood pressure.”

         -Joseph H. M.D.

     
    If you’re not familiar with EIM or would like an update, please visit the EIM website and learn more about this great program. Or read this article about exercise prescription and EIM from The Pharmaceutical Journal. For more about ACSM’s Approach to Partnerships, go here

     

     

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