Mike Clark

Getting In The Zone

Many treadmills, elliptical trainers, and bikes employ the notion that different exercise training intensities, like exercising at lower heart rates can elicit superior “fat burning,” or exercising at higher heart rates will elicit superior “cardiovascular training.” But, given the vast amount of exercise information, or misinformation available, you probably have some skepticism over claims like this. So…is it true? The answer is undoubtedly yes. Exercising at higher and lower heart rates does in fact prioritize the usage of fats over carbohydrates, or vice versa, depending on how high the heart rate goes. But, please read on to understand why...

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Exercise & The Brain: New Benefits

Mike Clark is an Exercise Physiologist and Personal Trainer at the Duke Center for Living at Fearrington. He received his BA in Exercise and Sports Science from UNC. It is well established that a structured exercise program can help prevent heart disease, stroke, cancer, and obesity. But what about the brain? When I was in the exercise science program at UNC we talked about endorphins, and how they increase with exercise to provide that “runner’s high” after a vigorous exercise session. But that was about it. Today there is a lot of research into how physical activity benefits the...

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A Brief History of the Exercise Recommendation

It’s interesting how we take health information for granted. Anecdotes are everywhere, most with little to no science backing them. Take water consumption for example; the long-standing recommendation is 8 eight-ounce glasses per day. Many, including some health practitioners, believe this recommendation is totally accurate. While I am sure it is/was well intended, the daily eight is anecdotal; handed down from who knows where. Currently, the Institute of Medicine (IOM) and the only institution with an actual dietary recommendation for water suggest that men consume the equivalent of 13 eight-ounce glasses a day, or roughly 40% more than the daily eight. For women, the IOM suggests the equivalent of 9 glasses or 15% more than the old standard. And while this article is not about water consumption, the above example does illustrate how health myths can become public fact. I think the everyday exercise recommendation, classically described as thirty minutes, five days a week, is a lot like the water recommendation concerning its presence in everyday life. It’s the “go to” for CNN’s chief medical correspondent Sanjay Gupta, first lady Michelle Obama, and others who try to promote exercise as part of a healthy lifestyle. But where does it come from, and why does it exist in the first place? And is it, like the old “Daily Eight,” based on nothing? Fortunately for us, the past and current exercise...

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The Skinny on Obesity: Part III

Low carb and high fat diets, high carb low fat diets, exercise programs named with mental illness monikers, shoes designed to tone and firm the bottom, pillows designed to keep us cool while we sleep… What’s next for a nation of consumers who got into trouble consuming too much in the first place? In the second of this four part obesity series, my friend and coworker Ellen Thornburg identified and discussed increases in portion sizes, decreases in physical activity, and faulty sleeping patterns as causes for obesity. And while obesity, like other chronic diseases, is complex in its nature, it is hard for any expert to argue that eating less, moving more, and sleeping better would not remedy the problem for most Americans. As the first paragraph suggests, finding our way out of this massive problem can seem complicated, though it need not be this way. Now, I know the mind loves novelty, but all the fads in the world can’t replace a healthy lifestyle that includes a nutrient rich diet, physically active lifestyle, and adequate time to rest. To discuss how exercise and diet can influence weight, we must discuss the concept of energy balance. This concept is governed by the Law of Conservation of Energy/Mass (given that Einstein is right), and thus weight loss, weight gain, and weight maintenance are governed by how many calories we consume...

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The Skinny on Obesity: Part I

According to the latest data provided by the Centers for Disease Control, nearly 4 out of 10 adults and 2 out of every 10 adolescents in the United States are now considered obese. While we certainly all know at this point that obesity is bad, what exactly does it mean to be obese? Hopefully this article, being the first of a four part series, will provide some clarification into this ever increasing weight epidemic. To define obesity, we must first consider the Body Mass Index, more commonly referred to as BMI, and how it is used to assign an individual’s weight status. BMI is defined by dividing an individual’s weight in kilograms by their height in centimeters squared. The equation itself was derived in 1832 by Adolphe Quetelet, a brilliant mathematician who submitted it as part of a greater investigation into the normal physical attributes of man. Don’t fret however, it’s not important that we know how to do the calculation, just that we know BMI is a ratio of weight and height, and that any internet calculator will yield the same results Once we have done the math we arrive at one number that represents an individual’s BMI. Since this BMI number accounts for an individual’s height and weight, their BMI can classify them as obese, overweight, normal or even underweight. The BMI to Weight Status categories are...

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