Apply this infographic as the basis for your hydration performance plan.

What does a good hydration plan look like? It is an approach that takes your unique sweat rate (fluid loss and sweat composition) and uses this information as a guide for what kind of fluid you should consider consuming, how much, and how often to maximize your performance.
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BONUS: Take the continuing education course, based on the article.

ACSM's Health & Fitness Journal®: July – August 2019 CEC Course #3: Individualized Hydration Plans for Ultra-Distance Endurance Athlete. Available ACSM CECs: 2.0

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This is part five of a series of blogs from attendees at ACSM's Conference on Integrative Physiology of Exercise. The following blog is a reflection on the symposium "Metabolic Flexibility in Health and Disease" by Ayland Letsinger. 

Carbohydrate and fat are the dominant fuel sources for energy production in our bodies. Everyone needs energy – from the most sedentary individual to the most elite athletes. On the one hand we often have trouble getting athletes to eat enough food given their high daily energy needs, while on the other hand many sedentary people who do not move much are consuming more energy than they need.

In a world where individuals crave the best diet for their needs, Lawrence Spriet, Ph.D., FACSM, of the University of Guelph led a symposium on metabolic flexibility at ACSM’s Conference on Integrated Physiology of Exercise. The discussion provided science-based advice for elite athletes, sedentary people and individuals with obesity and type II diabetes. 

Dr. Spriet opened with a complex image outlining the major pathways that allow the tissues in the human body (i.e. skeletal muscle) to use fat and carbohydrate to produce energy. He commented that, “My students hate when I show this diagram, but it is important to see the whole picture of fat and carbohydrate metabolism in order to make informed choices. They call it the ‘Dreaded Metabolic Pathway Diagram.’”

The key point was clear: the impressive and tremendous “flexibility” to alternate between carbohydrate or fat utilization to meet the energy demands of the body is critical for optimal performance and health. And this is most impressive when responding to single and repeated bouts of exercise. The following impressive cast of scientists supported this point with elegantly performed studies.

"the impressive and tremendous “flexibility” to alternate between carbohydrate or fat utilization to meet the energy demands of the body is critical for optimal performance and health."

Carbs: Friends or Foe? 

The high fat/low carbohydrate diet is being touted as a game changer for improving endurance performance and has become common among non-athletes. Louise Burke, Ph.D., FACSM, presented very convincing evidence showing that low carb/high fat diets had no clear benefit for low intensity exercise and simultaneously ruined high intensity performance in endurance athletes.

She let the audience know her studies were followed by a barrage of angry Twitter warriors calling her work poor and claiming the studies were not long enough for the athletes to adapt to the diet. However, Dr. Burke and others have shown humans on a low carb/high fat diet DO in fact adapt and have increased ability to utilize energy from fat.

Although, primarily using fat as fuel is less metabolically efficient than using glucose (the total energy yield is lower), glycogen (stored glucose) utilization is impaired, and certain high intensity points in endurance races (think of uphill portions or the final sprint to the finish line) requires carbohydrate usage for optimal performance.  In other words, the improved utilization of fat for fuel means losing vital efficiency in glucose utilization. 

"the improved utilization of fat for fuel means losing vital efficiency in glucose utilization."

 

The work of Bret Goodpaster, Ph.D., in studying individuals with type 2 diabetes, has revealed a decreased ability to store fuel (fat and carbohydrate) after a meal and severely impaired metabolic flexibility in utilization of fat and glycogen.  Simple exercise and weight loss programs, individually and together, restored much of the lost ability to store fuel and the flexibility to use it in skeletal muscle and the whole body. The messages were clear: you have to move more, and don’t overeat.  

Deb Muoio, Ph.D., closed the symposium by giving a great illustration of how important the mitochondria are for maintaining metabolic flexibility and health. These are the organelles in all of our cells where the majority of our energy is produced. The mitochondrial volume in cells increases when you are physically active and shrink when you are not. She showed that metabolic inflexibiliy is like a traffic jam in the common carbohydrate and fat utilization pathways that exist in the mitochondria. In simpler terms, a high fat/low carb diet is not the secret to health improvement, as exercise is proven to improve optimal metabolic function.

Finding the “perfect diet” for everyone is likely fleeting, but all four presenters agreed on a similar theme: the body’s ability to utilize both carbohydrates AND fats is critical for optimal performance and health. If you decide to remove either substrate, your body will miss that critical fuel.

Read part 1 of this series: "Can Exercise Fill the Reductionist Gap? Reflections on Dr. Michael Joyner's Keynote."
Read part 2 of this series: "Are Exercise 'Mimetics' a Realistic Substitute for Exercise Training? Reflections on the Debate." 
Read part 3 of this series: "Exercise and Energy Restriction to Improve Health: Recent Research." 
Read part 4 of this series: "Molecular Transducers of Physical Activity (MoTrPac) Update." 

Author: Ayland Letsinger is a Doctoral Student at Texas A&M University. Ayland was presented with an award for poster presentation at ACSM's Conference on Integrative Physiology of Exercise in 2018 for the abstract titled: A High Fat/High Sugar Diet Alters the Gastrointestinal Metabolome in a Sex Dependent Manner.

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We all know that you are busy and have unique needs. This is why we created a certification exam prep infographic for you:

Build Your Personal Certification Exam Prep Plan

If you’re considering an ACSM certification, you may be asking, “what do I need to do to prepare?” The short of it is that there is no one-size-fits-all study plan. Every person has a different way of learning and level of experience with the material.

One of the best ways to get started is to use the exam content outline. The exam content outline will give you an idea of the breadth and depth of content that will be addressed on an exam. In addition, the exam content outline provides a list of job tasks that are related to each content area.

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Let this infographic be your guide to setting up your customized exam prep plan!
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That which was old is new again. High-intensity interval training (HIIT) has been a common component of exercise regimens designed to improve fitness and performance for many generations. In recent years, research interest has surged. A simple search of PubMed for the term “high-intensity interval training” reveals a more than 20-fold increase in the number of hits between 2005-09 and 2015-2019. The increase is due to the possibility, rather likelihood, that HIIT provides health benefits in addition to fitness benefits. The July 2019 issue of Medicine & Science in Sports & Exercise (MSSE) alone included four articles reporting investigations of the relationship between HIIT and health indicators.

The 2018 Physical Activity Guidelines Advisory Committee (PAGAC) recognized the importance of the relationship between HIIT and health and included an umbrella review in its final Report. The search was updated, and the write up was revised and included in a Special Communications section of the June 2019 issue of MSSE as High-Intensity Interval Training for Cardiometabolic Disease Prevention. The PAGAC Report and the article conclude that HIIT improves insulin sensitivity, blood pressure, and body composition equivalent to the improvements provided by moderate-intensity continuous training.

 

The basic structure of HIIT is generally understood – short periods of high intensity exercise alternating with usually longer but still brief periods of lower intensity exercise. In practice, however, the format varies considerably. The duration of bouts of high intensity, the duration of periods of recovery, the specific intensity of high intensity, the specific intensity of the recovery periods and the number of cycles vary.

HIIT deserves the resurgence of interest because HIIT-related research, using device-measured physical activity, can refine our understanding of the relative importance of frequency, duration and intensity of physical activity. The prevailing conclusion, based largely upon self-reported physical activity, is that total volume of moderate-to-vigorous physical activity (MVPA) – the product of frequency, duration, and intensity – is more closely related to health benefits than any of the three components. The prevailing conclusion may, indeed, prevail. But HIIT research in which frequency, duration, and intensity are varied may provide new insights. HIIT research may even be able to contribute to our understanding of the health benefits of light intensity physical activity as well as very short episodes of MVPA.

The acceptability of HIIT regimes also deserves more study. The best physical activity regimens are the ones that people can and will continue to do over the years. Adherence to HIIT over time, as well as when and for whom HIIT is appropriate remains to be determined. In addition, the rates of musculoskeletal injuries and other activity-related adverse events are likely to be higher than for activity at lower intensities. Risk of injury is directly related to size of the physiologic overload, that is, the size of the increase in volume or intensity. Although the reputed injury and drop-out rates from HIIT have been small, the populations have been small and selective, and follow-up periods have been short.

The currently high level of interest in HIIT provides us with opportunities to explore many important and interesting physical-activity related questions. I’m glad it’s back! 

Learn more about the Physical Activity Guidelines for Americans, 2nd Edition 

Kenneth Powell, M.D., MPH. FACSM, was an epidemiologist with the CDC for 25 years and with the Georgia Department of Human Resources for 8 years. He is now retired and lives in Atlanta. The relationship between physical activity and health has been an important theme during his career. He planned, chaired, and edited the papers from the first national workshop on the epidemiologic and public health aspects of physical activity and exercise in 1985. Dr. Powell served on the Institute of Medicine Committee on Physical Activity, Health, Transportation, and Land Use (2005); Committee on Progress in Preventing Childhood Obesity (2008); and Committee on Physical Activity and Physical Education in the School Setting (2013). He was a member of the 2008 Physical Activity Guidelines Advisory Committee and a co-chair of the 2018 Physical Activity Guidelines Advisory Committee. He is a graduate of Harvard College, Northwestern University School of Medicine, and the Harvard School of Public Health.