Obesity: It’s in your jeans. And your genes.

Have you ever noticed that some people struggle to lose weight while others seem to have no trouble maintaining a healthy body weight? Why is it that some people lack the motivation to exercise while others are can’t seem to stop moving? What about people who appear to have no interest in desserts while others have a “sweet tooth”? Why do overweight parents tend to have children who are also overweight?

The traditional answer is that some people lack willpower which makes it more difficult for them to make healthier eating and activity choices. While motivation and dedicated effort are essential for making healthy choices, genetic research has resulted in the identification of a host of genes that appear to affect physical activity and eating habits, food preferences, and responses to a diet or exercise program.

obese jeans


The link between genetics and obesity is not new. Decades ago researchers found that obesity tends to cluster in families. But is this due to shared genes or a shared environment? The answer is both, but heredity plays an important role. Studies of siblings raised apart show that their body weight and fatness more closely resembled each other than the families they lived with. Other studies show wide variation in body weight among relatives, where some are obese but others are at a healthy weight. This suggests that although genes can predispose people to being overweight, personal behavior can modify this risk.

Genetic variations also explains why people respond to exercise training differently. Much of this knowledge comes from the Heritage Family Study which examined body fatness, fitness, and other health factors in over 700 individuals from 130 families. After completing the same exercise program, some people improved their fitness significantly while others experienced only a minor improvement. The prevailing explanation was that varying degrees of compliance accounted for these differences, but the Heritage study showed that genetic factors were at responsible for 40–50% of the variation in both initial fitness and improvement in fitness.

Your genes can also influence what you eat. Eating habits, including how much you eat as well as food preferences, are at least partly under the control of certain genes. Two separate genes that regulate appetite and the type of food people eat, have been identified. This might explain why some people say they always feel hungry while others are satisfied after a small meal or why  some people crave foods that are high in sugar and fat while others do not. Of course, what you eat is a behavior that you can control—you are putting the food in your own mouth, right?—but it is interesting to know that there are genetic factors that make these decisions more challenging for some.

Does this mean that healthy behaviors including eating and exercise are out of your control? Does it give you an excuse for being unhealthy? Absolutely not! Your genes may predispose you to certain health conditions, meaning you are at higher risk, but they do not predetermine your health. The expression of these genes is modifiable by your environment and your behavior. Even though you may be at higher risk for obesity, you still need to eat too much and not be active enough to gain weight. Be aware that “too much” varies greatly among people, so there is no single eating and activity pattern that applies to everyone. But knowing that you have a family history should give you even more motivation to eat a healthy diet and get regular exercise.


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School gets out, weight goes up: Why summer time is the right time to worry about childhood obesity.

Obesity is a major concern for adults, linked to several leading causes of death and numerous other health problems. What you may not know is that obesity is also a serious health issue for children. It is troubling to note that nearly one-third of school-aged children and teenagers are over a healthy body weight and nearly 20% are considered obese. Remarkably, 10% of infants, toddlers, and preschoolers, are also considered obese.

This is important because the common combination of poor nutrition, physical inactivity, and obesity has physical, psychological, and social consequences for children that frequently persist into adulthood. There are many reasons why childhood obesity occurs and much that can be done to prevent it. Now that school is almost out for the summer, this is a critical time of year to focus on good nutrition and activity to help prevent unhealthy weight gain in kids. This is the topic of my Health & Fitness column in the Aiken Standard this week.

kids-jumping


Overweight and obese children are at increased risk for type 2 diabetes, high blood pressure, heart disease and even stroke – conditions usually associated with adulthood. Even if an overweight child does not have these conditions now, he or she is likely on that path. Many experts predict that children born today will be the first generation in history to have a shorter lifespan than their parents due to obesity-related diseases that begin in childhood.

Children who are overweight are also more likely to suffer other consequences including lower self-esteem, social functioning, and academic performance. Overweight children are also less likely to play sports or participate in other forms of physical activity. Considering that the consequences of obesity are made worse by low levels of activity, this creates a cycle leading to poorer and poorer health.

There are numerous potential causes of obesity in children, but the most likely suspects are too little activity and excessive calorie intake, largely because of added sugars. Fewer than half of all kids meet the minimum recommendation of 60 minutes of activity each day and many children spend as much time watching television or playing video games as they do in school. We shouldn’t be surprised that we have a childhood obesity problem!

While poor nutrition and a lack of activity in schools is thought to contribute to the problem, many children get more activity and eat better at school than they do at home. A recent report suggests that children gain more weight over the summer than during the rest of the year. Furthermore, for many kids, fitness gains made during the school year are frequently lost over the summer. Since summer vacation is rapidly approaching, this is a critical time to help our children stay fit and healthy.

The good new is there is much we can do. Ensuring that children get plenty of healthy foods such as fruits and vegetables, reducing the consumption of added sugars, and eating appropriate portion sizes will go a long way to addressing the diet aspect of obesity. Making sure that kids of all ages have opportunities to be active while limiting time spent sitting, especially in front of a screen, are equally important.

Since children don’t make most of the decisions about their activity and diet, it is important to recognize the role that parents, grandparents, and other caregivers play. More often than not, obesity is a family issue. This means that  solving the problem is a family issue, too. Adults should model healthy behaviors by making diet and activity changes themselves. A good place to start is by turning off the TV and going outside to play or for a walk. It’s something all of us—adults and children—will benefit from.


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Is it true that you burn 100 calories when you walk or run a mile? Yes!

 

Walking and running are widely used modes of exercise to improve fitness and promote weight loss. The energy expended (calories burned) during walking or running can be directly measured in a lab or estimated based on speed and body weight. It can also be determined using one of many wearable devices and mobile apps. A commonly used estimation is that walking or running one mile elicits an energy expenditure of 100 calories.

This estimation, while crude, is interesting because of its wide use and apparent acceptance, even though it hasn’t been tested for accuracy. Research we did in the Exercise Science Lab at USC Aiken and presented at the American College of Sports Medicine annual meeting last week examined the accuracy of the 100 calories per mile estimate across a wide range of walking and running speeds. This is the topic of my Health & Fitness column in the Aiken Standard this week

100 kcals


To do this we asked subjects ranging in age from 20 to 44 years to walk or run one mile at a speed they selected on a treadmill while energy expenditure was determined. Some of the subjects walked and some ran, so the speeds ranged from 3 to 7 mph. For accuracy, we measured the air they breathed to measure how much oxygen they consumed to calculate how many calories they burned.

We found that the measured energy expenditure across all speeds was 108 calories per mile. It was higher (115 calories) during running and lower (98 calories) during walking. None of these were significantly different from the 100 calories per mile estimate.

There was a high degree of variability among subjects in energy expenditure, even at similar walking or running speed. This was due to body weight, with heavier people burning more calories when they walked or ran.

These findings are consistent with previous studies that compared the measured energy expenditure of walking and running one mile at set speeds. In our study, we allowed subjects to select their own walking or running speed, so it more closely reflects how people would exercise outside of a research setting. Research also shows that the energy expenditure during treadmill exercise was almost exactly the same as walking or running on a track, so our findings would also be applicable to walking or running on level ground.

In conclusion, the widely used estimate of 100 calories per mile appears to be accurate across a wide range of walking and running speeds. This supports using the 100 calories per mile value for estimating energy expenditure for fitness or weight loss purposes. For example, some exercise programs prescribe exercise based on calories burned rather than time or distance. And people who are trying to lose or maintain weight can use the 100 calories per mile estimate to help balance their energy intake and expenditure.

It is important to note that the 100 calories per mile estimate does not replace more accurate measurements or calculations that are done in a research or clinical setting. And wearable devices and apps are easy ways to get a good idea of how your energy expenditure during a wider range of activities. But, if you want to know how many calories you burn during a run or how long you need to walk to offset what you eat, the 100 calories per mile estimate will give you a pretty good idea.

 


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Hunger games

One of the most powerful motivators we have is hunger. Seeking food when we are hungry is what allowed our ancestors to survive. For most of human history, finding the next meal could be arduous or even dangerous, so a strong physiological drive was necessary to make it happen. Now, though, the problem isn’t usually finding food, it’s having access to too much food. Unfortunately, the regulation of hunger in our brains hasn’t changed.

The physiology behind why and when we eat is the topic of my Health & Fitness column in the Aiken Standard this week.

hungry child


Hunger is an internal physiological drive to seek and eat food and is usually experienced as a negative sensation. When you are hungry you may be distracted when your stomach growls. Since most of us have a supply of food that is readily accessible, severe hunger is uncommon. But when people diet to lose weight, especially a restrictive diet, hunger can be a powerful signal to eat.

 

Often when we think we are hungry, it isn’t hunger at all—it’s our appetite. Appetite is a psychological, as opposed to physiological, sensation that drives us to eat. Hunger and appetite can work together, but not always. The sight or smell of food can trigger can increase our appetite even if we aren’t hungry. Appetite tends to be more specific, too. While hunger will drive you to eat pretty much any food, appetite usually pushes you to eat a certain food.

 

One of the reasons we overeat is because we confuse appetite with hunger. We may think we need to eat when we see a food advertisement on television or smell someone cooking, but we really don’t have a physiological need for nourishment. Think about eating dessert after dinner. You just ate a full meal, so you can’t possibly be hungry. But when you see the dessert tray you develop an appetite for something sweet, even though you don’t need it.

 

Satiation and satiety are two other factors that influence what you eat. Satiation is the feeling of satisfaction or fullness that signals the end of a meal. Satiety is the effect of one meal, including the amount and type of food you eat, on how much you eat later. You can use these biological factors to your advantage to help you eat less.

 

For example, if you eat quickly you will eat more food (and calories) before satiation occurs. If you eat more slowly, you may actually eat less before that same feeling of fullness occurs. Additionally, what you eat for breakfast will impact when you feel ready for lunch and how much you eat when you do. It turns out that protein has a greater effect on satiety that either carbohydrates or fat. If your breakfast is juice and a donut you are likely to feel hungry sooner compared to having something with protein, like yogurt or eggs.

 

Genetics also play an important role in what we eat. Research suggests that how much we eat and even our food preferences are controlled, at least to some extent, by genes. Of course, some of this has to do with learned behavior, too. Maybe you prefer certain foods because you have a strong positive association with them developed throughout childhood.

 

One important point to remember is that no matter how strong the effect of genetics on food preferences, eating is a behavior that you can control. Your genes give you a predisposition, not a predetermination, meaning that even though you can’t change your genes, you can make an extra effort to not let them define you.


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A two-hour marathon is possibly possible now.

Earlier this month a runner attempted to complete a marathon (26 miles and 385 yards) in under two hours. For distance runners and sports scientists, a sub two-hour marathon is a bit like the four-minute mile once was—an arbitrary, but significant, goal. The current world record for the marathon is just under 2 hours and 3 minutes (2:02:57). To cut 3 minutes off that time would be a remarkable feat considering that it took almost 20 years to lower the record three minutes from 2:06 to 2:03. The continued quest for a sub-two hour marathon is the topic of my Health & Fitness Column in the Aiken Standard this week.

 

running feet


First, let’s put a two-hour marathon in perspective. To do it would require sustaining a running speed of over 13 miles per hour for two hours. Most runners I know would be hard pressed to complete the 385 yards at that pace…forget about the 26 miles that come before it! It is also more than twice as fast as the average marathon time of over 4 hours. If you are brave you can experience how fast this is yourself by getting on a treadmill and cranking the speed up to 13 miles per hour. Hang on, though, because you won’t last long!

 

The recent attempt to break the two-hour mark featured the accomplished Kenyan marathoner Eliud Kipchoge, whose personal record was just over 2:03. The effort was as much about running technology as it was about human performance. The shoes he wore were designed by Nike to be exceptionally light and provide extra recoil to propel the runner forward. The race was run on a Formula One track in Italy that was smooth and flat and was completed early in the morning when the weather was cool with low humidity.

 

During the race, a group of runners ran in front of Kipchoge to break the wind so he could draft much like race cars do. These runners also acted as pacers, keeping him at the right speed to break the record. There was even a pace car that projected a line on the road for the runners to follow. Water and sports drinks were provided by assistants on bikes so the Kipchoge didn’t need to slow down to replenish fluid and carbohydrates. In all, it was a perfect scenario to run a sub-two-hour marathon.

 

Despite all the preparation and efforts during the race, Kipchoge just missed the goal, finishing in 2:00:25—less than one second per mile off the mark! This suggests that breaking the two-hour barrier for a marathon is achievable, but is still a significant challenge. In fact, because of the pacing strategy used, this run is not considered a world record.

 

Other groups are also working to get a runner past the two-hour mark. One, led by sports scientist Yannis Pitsiladis, is taking the approach of enhancing training and to promote better performance. I have written about the physiological foundations of running performance related to the sub two-hour marathon previously.

 

While the two-hour marathon is still a goal for many, the sports science, technology, and training advances currently being explored exciting. Like the “shark skin” suits worn by swimmers and aerodynamic bikes used by cyclists, improvements in running technology are likely to be both beneficial and controversial. None of these advances can offset the physiological adaptations that result from years of dedicated training, so the best way to prepare for your next race is to put in time running, whether you are wearing the newest, fastest shoes or not!


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Exercise musicology

There are many tools, or ergogenic aids, athletes use to improve exercise performance. These include nutrients like carbohydrates, drugs like caffeine, steroids, and techniques like blood doping. Some of these performance-enhancing substances are illegal or banned, so ergogenic aids often have a negative image. Furthermore, many only work for highly trained athletes. But there is one ergogenic aid that has been shown to enhance performance in everyone. In fact, there is a good chance you use it when you exercise. That ergogenic aid is music. This is the topic of my Health & Fitness column in the Aiken Standard this week.

Exercise music

Music is a psychological ergogenic aid is known to affect mood, emotion, and cognition. More and more research also shows that music can also enhance exercise performance. In most gyms, there is music playing in the background and many people listening to music using headphones while they exercise. A practical reason, of course, is that listening to music makes the exercise more enjoyable by providing a mental distraction. It turns out that music has additional psychological and physiological effects that can improve exercise performance.

Not only can listening to music make exercise more enjoyable, it can also help you get a better workout. Research suggests that when exercise is coupled with motivational music, people tend to exercise at a higher intensity. They also tend to fatigue at a slower rate leading to longer exercise sessions. This is also associated with a lower rating of perceived exertion, meaning the exercise might feel easier!

Tempo is an important aspect of music that contributes to performance. People tend to prefer a tempo that matches the exercise intensity. Fast tempo music fits well with higher intensity exercise, like running, and music with a slower tempo is suited for lower intensity exercise, like yoga. But music tempo can also influence the intensity of exercise. Music with a faster tempo can promote more vigorous exercise, as measured by a higher heart rate, and a longer distance covered when running or cycling.

Listening to music before exercise can also affect performance. Studies have shown that listening to music prior to exercise can improve motivation, arousal, and focus. This is probably why you see athletes warming up before games and races wearing headphones. Research also suggests that listening to music during cool down can decrease recovery times, as measured by blood lactate levels.

While listening to music may increase exercise performance, the benefits vary based on the type of music. First of all, music that a person does not like is unlikely to elicit any positive impact on performance, so pick something you enjoy listening to. Another factor of music that can influence performance is whether it is synchronous or asynchronous. Synchronous is when a person matches their movements with the music they are listening to. This is particularly effective for running, cycling, and rhythmic exercises like aerobics. Asynchronous is when the music and the movements of a person do not match, which may still provide ergogenic benefits for certain types of exercise.

Listening to music during exercise can make your workouts more effective and enjoyable. Music you like can distract you from sensations of intensity and fatigue and lead to longer training sessions. Music played at a fast tempo can make you exercise harder and slower tempo music can help you relax. But you probably knew that already—sometimes sports science makes sense!

What if you prefer to exercise without music or other distractions? Like all ergogenic aids, the additional effect of music is small compared to the great benefits of the exercise itself, so keep doing what you are doing.


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After the ouch: New ways to treat minor sports injuries.

If you play sports or exercise regularly you probably have experienced some sort of injury. Hopefully yours was just a minor muscle strain, joint sprain, or soreness that didn’t prevent you from continuing your exercise program. It is always best to address minor injuries before they progress to cause more lasting damage.

If you do sustain a muscle or joint injury you will probably ice the affected area to help it heal. But there are also several newer techniques that can help speed recovery. This is the topic of my Health & Fitness column in the Aiken Standard this week.

Kinesio tape


The most common recommendation for treating a minor exercise injury is to use ice to reduce swelling and speed healing. For example, an ankle sprain might be treated by sitting with the injured leg elevated while applying ice; later the joint might be wrapped with athletic tape to provide support and further reduce inflammation. This combination is called RICE—rest, ice, compression, elevation—and makes intuitive sense.

Several other treatments for sports injuries have become more commonly used thanks in part to their use by professional and Olympic athletes. This is also due to the realization that inflammation is a key component in tissue repair and reducing it with ice therapy might actually interfere with healing. More and more sports medicine professionals are using modalities— voodoo flossing, cupping, and kinesio taping—other than (or in addition to) RICE to treat many injuries.

The benefits of compression for injury healing can be achieved by tightly wrapping an injured area with a rubber band, called “floss,” for a short time, usually less than a minute. This technique, commonly called voodoo flossing, is used to increase joint mobility and speed healing of minor injuries. Tightly wrapping a joint does has several potential effects by which it can improve movement and reduce pain. This includes allowing tissues to move more freely and increasing blood flow to the injured area.

Cupping gained much attention when swimmer Michael Phelps appeared at a race in the 2016 Olympics with large red welts on his back. He wasn’t hurt, as many feared. Rather, he was using cupping as a technique to treat injury and improve performance. Cupping literally involves the application of glass or plastic cups to the skin for several minutes, typically 5–15 minutes. Using either vacuum or heat, the cups pull the skin away from the underlying muscle tissue, increasing blood flow and improving movement. While cupping may be new to most of us, it has been used since ancient times and factors prominently in traditional Chinese medicine.

While voodoo flossing and cupping have a role in treating injuries and improving performance in the training room, there is a relatively new modality that can be used during exercise to enhance performance. Kinesio tape, also called K-tape, is applied over specific muscles to reduce pain and improve movement. The tape pulls the skin away from the underlying muscle, which increases blood flow and enhances movement, much like cupping. The difference is that kinesio tape can be used during exercise, as many people first saw on the shoulders of beach volleyball players in the 2008 Olympics.

While many sports medicine professionals still recommend RICE as a first line treatment for minor injuries, they are increasingly utilizing these alternative treatments. With a little training, people can use these techniques at home to treat some of their own minor injuries. Obviously, it is important to learn how to properly do these treatments and evaluate whether they are working. Improper treatment can delay healing and may make some injuries worse, so these treatments might be best done by trained professionals. And some injuries do require attention by sports medicine professionals. That said, if you are looking for an injury treatment beyond RICE, voodoo flossing, cupping, and kinesio tape might be worth trying.


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