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 brain, which goes well beyond helping you feel better a couple of hours after the exercise session. Currently, there are three emerging benefits for the brain that scientists are currently studying.

To begin, the brain can be likened to a computer, with both hardware and software. The brain’s “hardware” consists of the actual cells and structures that form the brain, like cells called neurons, gray and white matter, and different sections to carry out clear-cut functions within the body, much like the medulla oblongata regulates heart rate and breathing rate. The “software” consists of cognition, moods, mental states, memories, and other less tangible qualities. You will be happy to see that physical activity and exercise can aid both the brain’s software and hardware.

The first notable benefit is software related, in that cardiovascular fitness levels have been shown to affect the symptoms of depression in both depressed and non-depressed people. Depression, 1 of the 4 recognized mood disorders, affects roughly 1 in 10 Americans each year. In a twelve-year follow up study published in 2009, researchers measured the depressive symptoms and cardiovascular fitness of eleven thousand men and three thousand women. The results showed that as fitness levels increase, depressive symptoms (i.e. feelings of hopelessness) decreased. The researchers concluded that men and women with the lowest level of cardiovascular fitness were at the highest risk of experiencing depressive symptoms. Additionally, over 25 previous studies show that physically active individuals have a 33% reduction in depressive symptoms, regardless of race, age, or medical condition. Additionally, if depression is already present in a sedentary individual, exercise can be a valuable therapy for decreasing the symptoms, much like antidepressants and talk therapy.

The next benefit is both software and hardware related, in that studies show that physical activity reduces the risk of cognitive decline in adults and older adults. Cognitive decline comes in the form of Alzheimer’s disease and other dementias, which can decrease brain cell number and brain mass, along with negatively impacting thought processes, memories and even moods. While the mechanisms that provide the exercise benefit are still unclear, studies show that cognitive function increases when individuals exercise, with the largest increases coming by way of executive function (i.e. decision making, etc). Dr. Bonita L. Marks, an exercise researcher and neuroscientist at UNC-Chapel Hill and Duke University writes about exercise and the brain: “it seems that physical exercise helps to maintain/preserve the structural integrity of the brain, presumably by facilitating better delivery and uptake of needed hormones, which are responsible for maintaining the existing brain cells and creating new ones. When we have healthy brain cells able to transmit thoughts effectively, we have better memory processes and can remember all the important things, like where you parked your car or where you last put your keys.” Multiple research studies are finding the same effect as Dr. Marks’.

The final benefit to mention is hardware in nature. Neurogenesis is defined as the development of new nervous tissue, and in the case of exercise training, new brain cells. While it was once thought that brain cells could not be replaced once destroyed, MRI and other advanced imaging techniques have proven otherwise. Surprisingly, neurogenesis is a process that takes place throughout life; though the rate slows as age increases. In studies of active and sedentary mice, researchers observed that the sedentary mice experienced normal decreases in neurogenesis and brain size. Exercising mice, however, maintained higher levels of neurogenesis and higher brain sizes, in spite of increasing age. What is also interesting is that there seemed to be higher brain volumes in the mice who exercised early in life, suggesting that the aerobic training may have had an accumulative effect on the brain. Exercise induced neurogenesis has also been observed in humans, and more studies are being conducted on if the new brain cells actually aid in learning, memory, daily function, and the prevention of cognitive decline.

The amount of exercise needed to provide the brain benefit is still under scrutiny. The current exercise recommendation calls for jogging, or an equivalent activity, twenty minutes, 3 days a week, or brisk walking for thirty minutes, 5 days per week. While these recommendations are based primarily on heart health and the prevention of chronic disease, Dr. Marks and other researchers believe this amount of exercise will also apply to brain health.


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 recommendation is based on six decades of observation and research, rather than anecdote.

To go back a bit, the first serious notions of exercise for health in America began in the late 19th and early 20th centuries, when it was a topic of conversation among physicians and health educators. During the early nineteen hundreds, physical hygiene, as it was called at the time, was promoted for performance in prestigious University settings and the military, with no regard to health or the public’s welfare. But Later, in a 1952 landmark study, researchers (Morris et al) showed that when male workers become more sedentary, their risks of heart disease and death increased in a predictable way. From that point the scientific evidence began to emerge, indicating that exercise and fitness had much more to offer than performance.

However, there were some problems associated with telling everyone to exercise in the late 1950’s and 1960’s. Despite emerging benefits, many physicians worried that physical exertion above the normal daily activities may make those with heart disease worse, so they often advised rest rather than exercise. What’s more, cardiovascular disease was still on the rise during the middle of the 20th century, and many health professionals felt that formal exercise may actually cause heart attacks in men above the age of 45. But, at that time there was an incomplete picture of what causes heart disease, as well as a lack of consensus on the finer points of the exercise prescription, namely how difficult an exercise should feel while it’s being performed.

In the early seventies studies began to show that structured exercise programs lead to better outcomes in many patient groups, primarily those with a history of heart disease. Since that time thirty plus health and fitness related recommendations have been issued. Most of them issued by organizations like the American Heart Association, the American College of Sports Medicine, and the YMCA. Surprisingly, today’s recommendation has not changed all that much from earlier editions, and for good reason. Put simply, as an individual goes from being sedentary to active the risk of death and disease drop in a predictable manner. Remember 1952?

The graph to the right represents why the physical activity recommendation came into existence, and why it really hasn’t changed too much in the last 50 years. Looking closely, you will see that as minutes of moderate physical activity increase (walking at three to four miles per hour), health risks, namely death and disease decrease.

So, in a world of advertisements, expert opinion, vitamins and supplements, you can rest assured that not everything you hear is taken from anecdote. Being physically active 30 minutes a day, five days a week at a pace that makes you breath harder, has been shown time and again to prolong life and reduce disease. And the best part; it does not have to cost anything.

Mike Clark is an Exercise Physiologist and Personal Trainer at Duke Center For Living’s Health and Fitness Center. He received his BA in Exercise and Sports Science from UNC.


The Skinny on Obesity: Part IV

In the first three installments of this series, Mike Clark and I defined obesity and the risk factors associated with reaching its unfavorable benchmarks. We have also identified the path that leads to obesity and, thank goodness, the path that returns or diverts away from the classification. In this New Year, as many individuals will contemplate, initiate, and, unfortunately, abandon resolutions to be healthier, it is important to understand that knowledge is not enough. While Mike and I may have shared a little more than you already knew about obesity, the fact is we do, for the most part, know the facts. The problem? Action.

Many wise souls have been credited for the quote, “insanity is doing the same thing over and over again, but expecting different results.” No matter who actually said it first, there is a lot of truth in the statement. Knowing now how obesity is either reached or avoided, the “secret” to accomplishing a healthy weight is taking action and applying this knowledge to your lifestyle. If too little exercise, too much food, and too little sleep lead to being overweight, then conversely enough exercise, food and sleep will lead to a healthy weight. So to change your course of action, so that you can truly expect different results, means you must in fact take “sane” action, that is, something different than what added the pounds in the first place.

A healthy weight is not a gimmick, seasonal sale, special event, sales pitch, or figment of your imagination. It does require work, effort and sacrifice, but don’t all worthwhile pursuits? Once you have made up your mind to take appropriate action toward a healthier weight, there are a few things to keep in mind that will help in your effort and sacrifice so you, too, can experience the blessings of health.

  1. Life happens. Kids and dogs make messes, cars break down, illness and injury happen, and sometimes it rains. Your best intentions may be sabotaged by life on occasion, but having some back-up plans in place can help you stay focused and successful when you cannot make it to the gym or your stomach growls while conveniently passing a fast food stop.
  2. It’s called a holiDAY. I love New Year’s, the Super Bowl, Easter, Memorial Day, 4th of July, Labor Day, Thanksgiving, my birthday and Christmas just like many other totally normal, good-food-lovin’ American. But consider for a minute the word “holiday”. Eat your Grandma’s cake, Aunt Jane’s macaroni and cheese, Mom’s sweet potato casserole, and Dad’s ribs with the secret sauce. And enjoy it… on that day. It’s not a holiweek, holimonth, or a holiseason, and it most certainly is not a holiyear. Love the day of celebration, and the people you celebrate it with, for what it is and flip the calendar to the next day.
  3. Partake in (some) trends. The dance craze has hit the fitness scene and it’s not going anywhere anytime soon. Detox diets are running rampant and books are sold by the millions. You can pump iron, maximize reps, run a race every weekend of the year, and you can dance to any beat from any culture that has ever existed. There’s a fitness craze for that! You can purchase food to be delivered to your door, you can count calories, points and sheep, and you can avoid anything or eat anything if you set your mind to it. There’s a diet for that! Find what you enjoy in exercise and food and you will be successful, period. The point of exercise is to move, so move how you choose. Food is fuel so you should eat actual food, not a bunch of processed, manmade ingredients, and if you enjoy it you will keep making it. The concern with trends in both areas is that you have to consider what is safe, realistic, and enjoyable for you. Do not restrict yourself too much, but do not be naïve to the positive and negative consequences.
  4. You deserve health. Your family and friends deserve a healthy you. When all else fails, because we’ve already established that life happens, remind yourself that you deserve to be happy and healthy. If you need more than willpower, find some “why power”. Keep a picture of your loved ones near your gym bag. Write yourself a list of all the events you hope to attend in the future. Find a pair of your old jeans from college and hang them front and center in your closet. Whatever you choose to do, remind yourself regularly that being comfortable in your own skin, and having health to enjoy all that life has to offer, is something you absolutely deserve.

We wish you only the best in your future endeavors and pursuit of a healthy weight. Now go be active!

Ellen Thornburg is an Exercise Physiologist and Personal Trainer at Duke Center For Living’s Health and Fitness Center. She received her BA in Exercise and Sports Science and Psychology from UNC.

image by Filimonas via flickr


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 and how many calories we burn. Simply put, you can lose weight on a cheesecake diet, as long as you burn more calories than you consume. To elaborate, think of your adipose tissue (fat cells) as a bank account. If we want a big bank account we spend less and save more. The opposite occurs when we go broke; we spend more money than we put in. This same intuition applies to our bodies. If we want to lose weight we must expend more calories than we take in.

On to some application. To find out how many calories you body needs daily go to this calculator and enter the required information. This tool will give you two numbers, the Basal Metabolic Rate (BMR), which is about how many calories your body would consume during the day if you were at rest, and a daily energy expenditure estimate, which will be the higher of the two numbers and takes into account the caloric cost of your physical activity plus your BMR. To lose weight, eat enough calories to match the BMR number, and let the energy for physical activity come from your adipose tissue.

For example, a sedentary 6 foot 175 lbs male would need roughly 1842 calories to meet the BMR, and 2579 to meet the energy needs for physical activity. Instead of eating 2579 calories per day, eat enough calories to match the BMR of 1842. Doing this will create a caloric deficit that will lead to losing weight at about 1.5 pounds per week. Numbers will vary for different body sizes and ages, but the most important thing to remember about losing weight is to burn more calories than we take in. This method is safe, effective, and ensures that your body is getting enough calories to function properly, unlike many low calorie diets. For the best result, pack in those BMR calories with whole foods, such as fruits, vegetables, whole grains, and lean meats. In doing this you will find that you can eat higher volumes of food, which can lead to satisfaction and fullness.

Adding formal exercise into the equation will lead to a greater caloric deficit at the end of the day. The American College of Sports Medicine recommends 150 minutes per week of moderate aerobic activity. This time must be thought of as extra physical activity done with the intention of improving your health, thus gardening, house cleaning, and running back and forth to the copier does not count. If all we need is 150 minutes per week of extra physical activity, dividing 150 by 7 days per week equals roughly 20 minutes of brisk walking per day. Additionally, these 20 minutes can be broken into five or 10-minute segments, so working in your daily exercise does not have to be the time drain you think.

You can expect to burn anywhere from 100 to 200 calories per day by doing the extra time. Though the numbers seem small compared to eating less, they add up over time and contribute to your calorie deficit. What’s more, exercise leads to a longer healthier life, lower blood pressure, better cholesterol, and feeling of well-being. In short, it’s free medicine.

According to the National Sleep Foundation, exercise, diet, and sleep are interrelated. Thus, not catching you Zz’s can feed into the downward spiral of obesity. For instance, a tired person is less likely to eat well and exercise, although these are the key ingredients to a better night’s sleep. In turn, being overweight or obese can increase the risk of sleep apnea, or the temporary cessation of breathing while sleeping, which, in and of itself makes weight loss more difficult. Visit this site to read more about how exercise, sleep, and diet are interrelated, and to learn more tips that will help you get a better night’s sleep.

In short, remember that weight loss is not rocket science, yet popular media complicates the issue to make money. Eating less, moving more, and getting adequate rest works for weight loss and will prevent and cure obesity. Stay tuned for the fourth and final installment of this series by Ellen Thornburg.

Mike Clark is an Exercise Physiologist and Personal Trainer at Duke Center For Living’s Health and Fitness Center. He received his BA in Exercise and Sports Science from UNC.

image by Filimonas via flickr


The Skinny on Obesity: Part II

How did we get here?

Reports on the ever-increasing obesity epidemic in our country are running rampant, so we should all know that the issue is a reality and is crippling us. In the first part of this series, my colleague Mike Clark defined what obesity is and how it can be measured. After acknowledging what obesity is, the next step is to clarify how we got here.

Why are Americans packing on the pounds? What decisions are we continuing to make that increase the likelihood of so many health risks and diseases? There are three categories to explore this week, including a lack of general movement and physical activity, poor diet choices and inadequate sleep.

Lack of movement

Our society has become sedentary. There is no question or denial of this statement. The latest report from the American College of Sports Medicine (ACSM) recommends at least 150 minutes of cardiovascular exercise each week, both resistance training and flexibility to include exercises for all major muscle groups two to three times per week and neuromotor exercises to maintain or improve balance, agility and the likes at least twice per week. Not only has the Centers for Disease Control and Prevention (CDC) indicated that only 20% of American adults are actually meeting these recommendations, ACSM has indicated that the failure to meet these recommendations is not the entire problem. Most Americans live such a sedentary lifestyle, defined as sitting at desks, in the car or in front of a television frequently and for long periods of time, even the 20% who are making a point to fit physical activity into their weekly routine may still be at risk for heart disease, diabetes and other complications.

Poor diet choices

There is also no question or denial that we eat far more than we used to. The National Heart, Lung and Blood Institute (NHLBI) issued some staggering comparisons of how our portion sizes have changed over the years. In the 1970’s, two slices of pizza totaled 500 calories whereas now two slices would pack 350 extra calories for a whopping total of 850 calories. A standard cup of coffee was 8 ounces and your additive choices were milk and sugar. The norm for a purchased cup of coffee now is at least 16 ounces with milk, sugar and whipped topping for a total of 330 calories. Bagels have gone from a 3-inch diameter with 140 calories to 5- or 6-inch diameter with 350 calories. And another unfortunate truth to our portion woes is that dinner plates have gone from a 10-inch standard diameter to 12 inches. Americans are simply sitting too long and eating far too much.

Inadequate sleep

Sleep is a critical component to overall health and wellbeing. Your brain is able to process information and store memories, cells can recover and regenerate, to name a few theories. Based on sleep research, adults require seven to nine hours of sleep every night, yet the CDC says one in three adults are sleeping less than five hours. The School of Public Health at Harvard University claims that so few hours of sleep results in a 15% increased risk of being obese. This link between lack of sleep and obesity may be due to altered hormones that regulate hunger, more hours awake to eat extra calories, decreased ability to make good decisions regarding food choice, and lack of energy for adequate exercise.

In summary, this sounds like an article from Negative Nancy herself. The sky may be falling over the USA to some degree, but there are answers and there is hope! Stay tuned for Mike Clark’s next article in this series that addresses why we need to correct our patterns and exactly how to do so.

Ellen Thornburg is an Exercise Physiologist and Personal Trainer at Duke Center For Living’s Health and Fitness Center. She received her BA in Exercise and Sports Science and Psychology from UNC.

image by Filimonas via flickr


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 as follows:

BMI Weight Status
<18.5 Underweight
18.6-24.9 Normal
25.0-29.9 Overweight
>30 Obese
> 40 Morbidly Obese

Now that we can see where the number comes from and what it means, let’s take a closer look with a few examples. Using this calculator we can see that anyone who is 5’10 and 210 pounds would have a BMI of 30.1, and would thus fall into the Obese category. So the same individual would need to weigh about 174 pounds to fall into the more desirable “Normal” category.

While the BMI may be quick, convenient, and good at classifying an individual’s weight status, it very often does not tell the whole story. The biggest problem being that BMI only accounts for the ratio of height to weight, and says nothing of density. Take for example basketball star LeBron James, who ESPN.com reports as being 6’8, 250 pounds. Via the calculation, James’ BMI comes in at 27.5, placing him squarely in the overweight category, only 2.5 BMI points away from obesity! This is possible because, even with his immense height and lean frame, James has so much muscle mass that his BMI comes out too high; so clearly the BMI falls short this case.

The BMI measurement can also fall short for individuals with too little muscle mass. Take, for example, an elderly individual with a height of 5’10, a weight of 170, and a waist circumference of 40 inches. While this individual looks to be overweight, he or she could have so little muscle mass and so much fat mass, hence the 40 inch belly, that the BMI comes up in the normal range. Individuals like this often have difficulty with activities of daily living, as these activities require a certain amount of muscular strength and endurance. Long story short, BMI should only be taken definitively when other measures of body composition are known, like waist circumference and percent body fat.

To conclude, the Body Mass Index is a good tool for researchers, clinicians, and the public to classify an individual’s weight status. Yet, as we have seen from a few examples, the BMI should be taken along with other measures of body composition to get a better picture of an individual’s weight status. Please expect more from this topic from the Duke Center for Living at Fearrington over the following weeks.


Mike Clark is an Exercise Physiologist and Personal Trainer at Duke Center For Living’s Health and Fitness Center. He received his BA in Exercise and Sports Science from UNC.


image by Filimonas via flickr