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Why is exercise good?

Why is exercise good?


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The fact that exercise is healthy is a bit counter intuitive to me. If we have any machine, a car for example, the less we use it the longer it lasts. Then how is it that using our body to do sports, to a reasonable amount, lead to longer or healthier life?

My guess is that lack of activity might resemble starvation no matter how much food we consume. Then the body instead of repairing itself tries to save energy as much as it can. Are there any other ideas to explain why exercise is good?


As jamesqf points out in comment, "the less we use it the longer it lasts" isn't always true even of machines. Sometimes if a machine isn't used, the moving parts start sticking together through rust or other decay processes, which does not happen when the machine is used and the moving parts move regularly against each other.

Another example that comes immediately to mind is a hybrid car, which needs to be driven regularly or the battery runs out. Granted this doesn't affect the car's longevity (I think?), but it is another example where use maintains functionality better than disuse does.

This is even more true when we actively maintain machines, fixing them as they break, replacing parts, oiling, etc.

The key point here is that decay is inevitable. It is a law of thermodynamics, and it doesn't care whether something is in use or not. Granted, things will sometimes decay faster if they're used, but not always, and they'll always decay either way. The only way to forestall decay is active maintenance. This isn't contradictory with decay being inevitable, because you can actively maintain something only for so long (it takes work and energy).

This is relevant to biological system because that is how our body works: it is constantly self-repairing and self-maintaining, for the length of the person's life. One reason we die is that it stops doing so as efficiently as one ages. But as long as we are living, these processes mean our bodies aren't a static object: they are a dynamic system that is constantly reacting to outside and inside stimuli. And that system, including the self-repair mechanisms, are set up such that they work best within a certain range of motion and activities. It so happens that range doesn't include "no motion or activities". Likely because we evolved as an active species, so being able to function efficiently when active is useful, and some of the things that make us able to function efficiently when active can cause some harm when we aren't. For example, we store fat in order to use it when food isn't available and as fuel for effort, but if too much of it accumulates it has effects on hormones and inflammation that our bodies don't deal with well. Another example is how our muscles waste away when we don't use them; this is useful for an active species that needs the muscles it uses and shouldn't waste energy and protein on those it doesn't, but an inactive species might be better off conserving its muscles through periods of inactivity, so that they would still be capable of moving well those rare times they do need or want to.

Having said that, look at high-level athletes getting injured, getting early arthritis, etc… It is possible to exercise more than the body's self-reparation abilities can handle, and that also leads to health problems down the road.


10 Benefits of Exercise for Circulatory and Respiratory System

Doing a regular exercise is a must. Exercise such as running can be the good option for people. This activity can boost the body health including to promote the energy production. Indeed, it cannot be denied that people who do exercise regularly get the healthier life for sure. In this case, exercise also brings benefits to promote the circulatory and respiratory system. Therefore, if you are curious what exercise does to that body system, then you can check the list of information below.

1. Promotes Breathing Rate

The benefits of exercise are numerous. One of them is to promote the respiratory system by promoting the breathing rate. It is due to the ability of exercise to changes in the concentration of CO2 and O2 in the blood. As a result, it will promote the rate of breathing for sure. Not only for that, the muscle will also work harder due to the exercise effect which can promote the inhalation of the air. Such the great benefits, right? You can also check on Health Benefits of Exercising Before Breakfast

2. Promotes Respiratory Health

One of the best benefits of exercise for the circulatory and respiratory system is to promote the higher cardiac output and the respiratory pump as well. Moreover, exercise can promote larger respiratory volumes lead to the more oxygen being diffused into the blood flow. As the consequence, with these abilities, it will bring benefits to promote respiratory system functions. Thus, you can do the regular exercise like running for sure. You can also check on Health Benefits of Clove Bud Tea

3. Promotes Heart Health

The first benefit of exercise for the circulatory and respiratory system is the way it promotes the heart health. It is due to its ability to release the adrenaline that leads to the rising of heart rate. Not only for that, the exercise also improve the amount of lactic acid which acts as stimuli to the cardiac control center. This is also lead to the increased heart rate as well. In fact, exercise can boost your heart rate from 72 to 200 beats per minute, depending on your fitness level and age. This is such a good news for those who want to have such a strong heart.

Apart from this benefit, exercise can help to build stronger heart walls and promoting the larger heart volumes. Then, the blood will be pumped greatly and the oxygen will be delivered to the body muscle. Thus, as you know that exercise offers the great benefit of this, then you will have no doubt to do it regularly. You can also check on Health Benefits of Potatoes

4. Improves Blood Pressure

By doing exercise regularly, the level of blood pressure increased as well as improving its flow rate. As a result, the delivery of oxygen to the body parts promotes as well. Then, this will enable the nutrients to improve the working muscle for sure. Besides, the more you do exercise, then your arterial walls will become more elastics which improves greater tolerance of changes in blood pressure. Indeed, this benefit is very important as it can increase the body functions. Thus, are you interested to do regular exercise such as running?

5. Prevents Certain Diseases

By promoting the circulatory and respiratory system, then exercise can actually prevent certain related diseases. In this case, you can prevent the heart disease as you can control the level of blood pressure by doing a regular exercise. What is even greater for exercise, it can help to prevent the type 2 diabetes, certain types of cancer, stroke, arthritis, and depression as well. Great, isn’t it?

6. Promotes Metabolism

By doing exercise regularly, then it will be valuable to promote the higher rate of muscle contraction. As a result, it will improve energy production and stimulated the higher rate of energy metabolism as well. Hence, it is recommended to do regular exercise like running in the morning to keep the good body metabolism.

To get the best benefits of exercise for the circulatory and respiratory system, then you need to do the right workout. In this case, aerobic can be the good option. It can help to boost the heart pumping and improve breathing rate as well. Another option you can have is by doing a regular exercise such as running, swimming, and practices in soccer.

After knowing the benefits of exercise for the circulatory and respiratory system, then let’s check other benefits of exercise below.

7. Helps to Lose Weight

he next benefit of exercise is to help losing weight. If you are the one who wants to manage the body weight, then you can count on the regular exercise. The exercise can burn calories and that will help to make your body fit as well. For the tips, if you want to lose the body weight effectively, then it is recommended to consume healthy foods including fruits and vegetables for sure. You can also check on Health Benefits of Drinking Diet Tonic Water

8. Boosts Energy

It cannot be denied that exercise can help to boost energy. It is due to the increased blood flow and promotes the nutrients absorption to the body parts. Thus, you can do exercise for having your body energized everyday. You can also check on Health Benefits of Whipped Cream

9. Promotes Bone and Muscle Health

As a matter of fact, exercise can promote the strong bone and muscle as well. The exercise can promote the muscle building by releasing hormones to absorb amino acids. Then, you need to do regular exercise together with consuming healthy foods which have the high source of minerals to promote the bone and muscle health.

10. Promotes Good Sleep

As the consequence, exercise can be beneficial to promote the good sleep quality. It is based on a study shown that you can get 65% improvement in sleep quality by doing 150 minutes of moderate-to-vigorous activity per week. As a result, it will prevent insomnia and make you feel more energized in the next morning.

To conclude, you can do regular exercise like running, swim, and aerobic to promote the circulatory and respiratory health. It will help you to promote heart health by increasing the blood flow. Then, it is recommended to do kind of exercise regularly to get the best benefits of it. Stay healthy, there!


Other mental health benefits of exercise

Even if you’re not suffering from a mental health problem, regular physical activity can still offer a welcome boost to your mood, outlook, and mental well-being.

Exercise can help provide:

Sharper memory and thinking. The same endorphins that make you feel better also help you concentrate and feel mentally sharp for tasks at hand. Exercise also stimulates the growth of new brain cells and helps prevent age-related decline.

Higher self-esteem. Regular activity is an investment in your mind, body, and soul. When it becomes habit, it can foster your sense of self-worth and make you feel strong and powerful. You’ll feel better about your appearance and, by meeting even small exercise goals, you’ll feel a sense of achievement.

Better sleep. Even short bursts of exercise in the morning or afternoon can help regulate your sleep patterns. If you prefer to exercise at night, relaxing exercises such as yoga or gentle stretching can help promote sleep.

More energy. Increasing your heart rate several times a week will give you more get-up-and-go. Start off with just a few minutes of exercise per day, and increase your workout as you feel more energized.

Stronger resilience. When faced with mental or emotional challenges in life, exercise can help you build resilience and cope in a healthy way, instead of resorting to alcohol, drugs, or other negative behaviors that ultimately only make your symptoms worse. Regular exercise can also help boost your immune system and reduce the impact of stress.


Weight Management

Looking to get to or stay at a healthy weight? Both diet and physical activity play a critical role in maintaining a healthy body weight, losing excess body weight, or maintaining successful weight loss. You gain weight when you consume more calories through eating and drinking than the amount of calories you burn, including those burned during physical activity. It&rsquos important to balance calories. When it comes to weight management, people vary greatly in how much physical activity they need. You may need to be more active than others to reach or maintain a healthy weight.

Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits. Learn more from the Physical Activity Guidelines for Americans, 2nd Edition pdf icon [PDF-15.2MB] external icon .

To maintain your weight: Work your way up to 150 minutes a week of moderate-intensity aerobic activity (for example, 30 minutes a day, 5 days a week). Strong scientific evidence shows that physical activity can help you maintain your weight over time. However, the exact amount of physical activity needed to do this is not clear since it varies greatly from person to person. It&rsquos possible that you may need to do more than 150 minutes of moderate-intensity activity a week to maintain your weight.

To lose weight and keep it off: You will need a high amount of physical activity unless you also adjust your diet and reduce the amount of calories you&rsquore eating and drinking. Getting to and staying at a healthy weight requires both regular physical activity and a healthy eating plan. For more information about nutrition, physical activity, and weight loss, visit Healthy Weight.


Research has shown that exercise is not only good for your physical health, it also supports emotional and mental health. You can exercise with a friend and get the added benefit of emotional support. So, next time you’re feeling down, anxious, or stressed, try to get up and start moving!

Read and share this infographic about the emotional benefits of exercise.

Physical activity can help:

  • Reduce feelings of depression and stress, while improving your mood and overall emotional well-being
  • Increase your energy level
  • Improve sleep
  • Empower you to feel more in control

In addition, exercise and physical activity may possibly improve or maintain some aspects of cognitive function, such as your ability to shift quickly between tasks, plan an activity, and ignore irrelevant information.

Here are some exercise ideas to help you lift your mood:

  • Walking, bicycling, or dancing. Endurance activities increase your breathing, get your heart pumping, and boost chemicals in your body that may improve mood.
  • Yoga. This mind and body practice typically combines physical postures, breathing exercises, and relaxation.
  • Tai Chi. This "moving meditation" involves shifting the body slowly, gently, and precisely, while breathing deeply.
  • Activities you enjoy. Whether it’s gardening, playing tennis, kicking around a soccer ball with your grandchildren, or something else, choose an activity you want to do, not one you have to do.

Biology - Exercise and Health (AQA)

Students of GCSE Science will look at the requirements of staying healthy. This is the second of six quizzes on that topic and it looks in particular at the effect that exercise has on our health.

Eating a balanced diet is an important factor in staying healthy, but so is exercise which has a positive effect on our health in many ways. During exercise your body's metabolic rate increases which means you burn more calories. Exercise also builds muscle mass. The metabolic rate of muscle cells is greater than that of other cells even at rest. Exercise therefore helps your body to control its weight more easily.

Exercise increases your heart and breathing rate which improves your circulation. The capacity of your blood to carry oxygen and get rid of waste from your cells is also improved. Being active boosts high-density lipoprotein (HDL), or "good," cholesterol and decreases the levels of unhealthy triglycerides. This double effect helps to reduce the clogging of your arteries and keeps your blood flowing smoothly, reducing your risk of heart disease, diabetes and strokes.

Returning blood to the heart from lower parts of the body (such as the feet and legs) is hard work for your circulatory system since this blood has to be pushed upwards against the force of gravity. Exercise gives your circulatory system some help from muscles that surround veins. When you walk or run, muscles in your feet and legs help squeeze the veins, pumping blood upwards. Improving your circulation helps your hands and feet keep warmer in winter.

Regular exercise also makes you stronger and fitter so you will be less tired during the day. Muscles become more toned and, over time, exercise becomes easier. Many vigorous activities help you build strong bones too, such as sports like gymnastics, martial arts and football which involve running and jumping. Exercise doesn't need to be vigorous all of the time! Moderate exercise, like going for a walk or gentle cycling, is also beneficial - and remember to include resistance exercise like push-ups, pull-ups, squats and lunges.

And for the days when you are feeling a bit down in the dumps - do some exercise! It stimulates the release of certain chemicals in the brain that are associated with relaxation and happiness. Exercise improves not only our health, but also our mood!


How Exercise Affects Your Brain

You have probably heard people say something along the lines of &ldquoyour brain is like a muscle.&rdquo That comparison certainly supports the brain training industry (by that I mean school) and keeps millions of youth around the world sitting at desks, doing math problems, writing essays, and dissecting unsuspecting amphibians - but is it true?

Interestingly, the brain-as-a-muscle comparison isn&rsquot all that accurate. If you want to build your glutes, you have to flex your glutes but when it comes to your brain, a more coincidental approach is more accurate. Getting busy working your glutes will also directly benefit your grey matter. Yes, exercising your butt will make you smarter!

Exercise affects the brain in many ways. It increases heart rate, which pumps more oxygen to the brain. It aids the release of hormones which provide an excellent environment for the growth of brain cells. Exercise also promotes brain plasticity by stimulating growth of new connections between cells in many important cortical areas of the brain. Research from UCLA even demonstrated that exercise increased growth factors in the brain which makes it easier for the brain to grow new neuronal connections.

From a more feel-good perspective, the same antidepressant-like effects associated with the "runner's high" has been correlated with a drop in stress hormones. A study from Stockholm showed that the antidepressant effect of running was also associated with more cell growth in the hippocampus, an area of the brain responsible for learning and memory. The study went as far as to say &ldquoThus, suppression of cell proliferation in the hippocampus could constitute one of the mechanisms that underlie depression, and physical activity might be an efficient antidepressant.&rdquo


Go with the flow

"The idea is that when you have a coronary blockage and you exercise, the area of heart beyond the blockage is starved for blood supply — more so than when you're at rest," says cardiologist Dr. Meagan Wasfy of the Cardiovascular Performance Program at Harvard-affiliated Massachusetts General Hospital. "That sets up a number of molecular and metabolic pathways that help the heart adapt to that inadequate blood flow," she explains.

Ischemic (or exercise) preconditioning is similar to something Dr. Wasfy and her colleagues hear about routinely from patients with heart disease who exercise. They start out on a run but feel tired or have angina fairly quickly, so they walk for a few minutes. "But once they start running again, it feels remarkably easier on the second try," Dr. Wasfy says. Known as "warm-up angina," this phenomenon was first described some 200 years ago.

The exact biological mechanism of ischemic preconditioning remains elusive. One theory points to a factor found in the blood involved in opioid receptor activation, according to the authors of the review article. More importantly, the benefits may extend beyond making exercise easier. Animal studies suggest that ischemic preconditioning seems to protect the heart if a heart attack does occur later on, reducing damage by as much as 50%.


The Science of Weight Loss

The Department of Health and Human Services (HHS) late this year released its new Physical Activity Guidelines for Americans, calling for adults between the ages of 18 and 64 to exercise moderately (such as brisk walking or water aerobics) for at least two hours and 30 minutes or vigorously (running, swimming, or cycling 10 mph or faster) for at least an hour and 15 minutes weekly.

The longer, harder and more often you exercise, the greater the health benefits, including reducing the risk of diseases such as cancer and diabetes, according to the recommendations, which were based on a decade of scientific research.

Studies have shown that people who engage in the amount of exercise recommended by the feds live an average of three to seven years longer than couch potatoes, according to William Haskell, a medical professor at Stanford University who chaired the HHS advisory committee. But how exactly does exercise accomplish this? And what about claims by naysayers that exercise not only isn't healthy but may actually be bad for you? Is there any truth to them?

Good for the heart and blood vessels
In the past decade or so, various studies involving thousands of participants have shown that workouts lower the risk of heart disease. "Exercise has a favorable effect on virtually all risk factors of cardiovascular disease," says Jonathan Meyers, a health research scientist at the Palo Alto Veterans Affairs Health System in California. The reason, he says: when a person exercises, the heart muscle contracts forcefully and frequently, increasing blood flow through the arteries. This leads to subtle changes in the autonomic nervous system, which controls the contraction and relaxation of these vessels. This fine-tuning leads to a lower resting heart rate (fewer beats to pump blood through the body), lower blood pressure and a more variable heart rate, all factors that lower the risk of developing cardiovascular disease, he says.

Meyers says that exercise also limits inflammation associated with heart trouble, such as arteriosclerosis or hardening of the arteries around the heart, which may lead to heart attacks. Many recent studies have focused on C-reactive protein, a marker of inflammation. Meyers says that research showed that sedentary folks who embarked on three- to six-month exercise programs, on average, experienced a 30 percent dip in their C-reactive protein levels &ndash about the same drop as someone given a statin (a cholesterol and inflammation-lowering drug). In other words, in many people, exercise might be as effective as an Rx in tamping down inflammation, one of the key risk factors for cardiovascular disease.

Exercise also boosts cardiovascular health by decreasing the amount of plasma triglycerides&mdashfatty molecules in the blood that are associated with plaque build-up in the arteries&mdash notes Haskell. What's more, he adds, physical activity helps reduce the particle size of low-density lipoprotein (LDL) or so-called bad cholesterol in the blood, and increase amounts of high-density lipoprotein (HDL), aka good cholesterol, which translates to less artery clogging.

But exercise may not have the same effect on every person's cardiovascular system, notes Arthur Leon, chief cardiologist at the University of Minnesota's Heart Disease Prevention Clinic in Minneapolis. "On average, there is a response but there is great variability, and that variability runs in families," he says. Take, for example, HDL cholesterol. Most broad studies show physical exercise leads to up to a 5 percent increase in HDL levels, but a closer examination shows that the percentages vary from zero to 25 percent, depending on the study subject, he says, noting that only about half of the population seem to experience HDL increases as a result of exercise.

Less cancer
Several studies (including the ongoing federal National Health and Nutrition Examination Survey) following thousands subjects for several years, show that regular exercise lowers the risk for certain cancers, particularly breast and colon cancer, says Demetrius Albanes, a researcher at the National Cancer Institute in Bethesda, Md. Scientists have yet to pinpoint the mechanisms involved but have come up with several plausible explanations.

"Physical activity beneficially affects body weight," says Albanes, noting that leaner people have lower circulating levels of insulin, a hormone produced by the pancreas that helps cells absorb glucose, their primary energy source. Obese and overweight people, are more likely to develop insulin resistance, a condition in which the cells no longer respond to the hormone and absorb glucose. When this happens, the pancreas produces greater amounts to compensate, flooding the bloodstream with insulin high levels of insulin in the blood have been linked to [some types of] cancer. "Insulin is essentially a growth hormone," Albanes says. "Insulin could create new tumors by increasing rates of cell division, or it could just make small tumors grow."

Albanes says that exercise may also ward off cancer and other diseases because it appears to beef up the body's immune system. Exercise may also help reduce levels of the female hormones estrogen and progesterone in the blood, potentially also lowering the risk of developing breast and uterine cancers linked to high levels of those hormones.

Despite the apparent link between physical exercise and lower odds of cancer, Albanes acknowledges that there could be other factors at work. "[Because] most of these studies are not controlled trials, it could be some other lifestyle factor [that helps explain the lower cancer risk], " he says, noting that people who exercise may also eat healthier diets.

Builds strong bones
Robert Recker, an endocrinologist and current president of the National Osteoporosis Foundation in Washington, D.C., says research indicates that moderate exercise increases and maintains bone mass and reduces the risk of osteoporosis. "The most compelling evidence," he says, "is that if you don't do anything, your fracture risk is much greater."

Like muscles, bones become stronger when forced to bear more weight than normal. "The skeleton is a smart structural organ and knows how much load [force] is being put on it," Recker says. "Pick up a pail of water, and you're loading your arm, your shoulder, your spine, your legs and your hips." That means muscles are contracting, exerting forces on the bones supporting those body parts. This force stimulates the bone to maintain or even build new tissue. But scientists have yet to figure out why. "That's a focus," he says, "of incredibly aggressive research."

Recker says that researchers speculate, however, that it has to do with exercise triggering osteocytes (the most mature bone cells) to instruct bone-building cells called osteoblasts to increase bone formation.

Wards off diabetes
According to Gerald Shulman, a cellular and molecular physiologist at Yale University School of Medicine in New Haven, Conn., exercising may prevent and even reverse type 2 diabetes.

Diabetes type 2 is a disease in which the body begins to ignore or fails to produce enough insulin (a condition called insulin resistance). If muscles and other tissues cannot absorb glucose from the blood, nerve and blood vessel damage ensues, paving the way for heart disease, stroke and infections.

"We've shown that in insulin-resistant individuals&hellip build up of fat leads to biochemical reactions that interfere with the glucose-transport mechanism [leading cells to block the activity of insulin]," Shulman says. But physical activity helps reverse this process. He notes that when someone runs, cycles or does other vigorous exercise, muscle contractions ramp up production of adenosine monophosphate-activated protein kinase (AMPK), an enzyme that promotes the breakdown of the fats interfering with the cells' glucose transporters.

"It is very likely that there are differences in the extent to which individuals respond to exercise, just as there are in responses to medications," says Ronald Sigal, a clinical epidemiologist at the Ottawa Health Research Institute in Canada. Leon agrees, pointing to research demonstrating that exercise leads to varying decreases on visceral body fat (the fat surrounding organs), one of the key risk factors for developing type 2 diabetes.

Makes you smarter

Researchers have long believed that exercise boosts smarts but there was not any hard scientific evidence until a few years ago. Now, says Fernando Gomez-Pinilla, a neurosurgery professor at the University of California, Los Angeles, it's known that exercise increases levels of some molecules in the brain that are very important for cognition.

One such chemical is brain-derived neurotrophic factor (BDNF), a molecule that promotes the growth and survival of brain cells as well as communication between them. Studies in rats show that physical exercise boosts BDNF levels in the hippocampus, a brain structure critical for learning and memory formation, which in turn helps them remember how to navigate their way through underwater mazes. "The more exercise, the more changes in the brain we found almost a linear relationship," Gomez-Pinilla says. "If we block the BDNF gene, we block this capacity of exercise to help learning and memory."

Numerous studies suggest that fitness enhances cognition in humans as well. A randomized clinical trial published recently in the Journal of the American Medical Association found that people 50 years and older with memory problems scored higher on cognitive tests after a six-month workout regimen. Those study participants assigned to exercise programs scored 20 percent higher than their sedentary peers at the end of the six months, and maintained a 10 percent edge one year after the trial ended.

But skeptics warn that not enough research has been done to confirm a link between exercise and human brain power. A recent review of studies on cognition in older adults (primarily those age 65 and older) by Dutch scientists published in the Clinical Journal of Sport Medicine concluded that "beneficial effects of various exercise programs on aspects of cognition have been observed in studies among subjects with and without cognitive decline. The majority of the studies, however, did not find any effect."

Weight Loss
The relationship between exercise and weight loss is complicated. Contrary to popular belief, working out at the gym every day will not necessarily lead to weight loss. "It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures," write the authors of the American College of Sports Medicine (ACSM) and the American Heart Association's (AHA) 2007 guidelines. "So far, data to support this hypothesis are not particularly compelling."

"Increasing physical activity&mdashif people control caloric intake&mdashwill lead to weight loss," says William Haskell of Stanford University who helped craft the HHS, ACSM and AHA guidelines. But he cautions that exercise alone is unlikely to lead to the instant results most people want, leading them to become frustrated and give up. "[Suppose I do] 30 minutes of brisk walking five days per week," says Haskell. "If you say walking a mile expends 100 calories, and if I walk at 3 miles per hour, I burn an extra 150 calories per day," he says. "[Since one pound of fat is equivalent to about 3,600 calories], it could take three weeks to lose one pound. For most people, they are going to find this disappointing, [and] probably won't stick with it."

So for the average person, caloric intake&mdashrather than calorie burning from exercise&mdashappears to be the most important factor in weight loss. But even if calorie intake trumps exercise, this does not mean exercise does not play a key role in helping people stay trim.

"If you talk about energy balance [when calories consumed equal calories burned], definitely there is evidence that exercise contributes to energy balance," says David Stensel, an exercise physiologist at the School of Sport & Exercise Sciences at Loughborough University in Leicestershire, England. A study published this month by Stensel's team suggests that vigorous exercise suppresses the key hunger hormone, ghrelin, for up to 30 minutes after workouts and increases levels of the appetite-suppressing hormone peptide YY for as long as three hours after exercise.

Stensel also points to studies showing that exercising may encourage people to crave healthier fare, such as unrefined foods (like fiber-rich beans and veggies) rather than foods loaded with refined sugar (such as cookies and cakes).

Some past researchers claimed that exercise would lead to weight gain in the long run because it ups one's appetite. But Arthur Leon of the University of Minnesota says that theory has been shot down over the past decade. Some research suggests that it might lead to greater caloric intake, Stensel notes, but that does not necessarily translate into extra pounds. The increased calories, he says, are not enough to offset the calories burned&mdashor energy consumed&mdashduring exercising.

The bottom line: couch potatoes may applaud the exercise naysayers but the bulk of research suggests that workouts make us physically and perhaps mentally healthier.


7. EXERCISE TRAINING: IMPACT ON HEALTHY PEOPLE AND PEOPLE WITH TYPE 2 DIABETES

Regular physical activity leads to numerous adaptations in skeletal muscle which allow the muscle to more efficiently generate ATP and become more resistant to fatigue. 102 In regards to carbohydrate metabolism, some of the key adaptations that occur in skeletal muscle with exercise training include enhanced glucose uptake and increased expression of GLUT4. 103,104 Trained muscles are also characterized by increased concentrations of glycogen, which is an important factor in the decreased rates of fatigue with prolonged exercise. Exercise training causes muscle fiber type transformation to a more oxidative and perhaps slow phenotype, 105� and an increase in mitochondrial activity and content. 108� In addition, exercise training can increase insulin sensitivity and improve overall glucose homeostasis, 111� which are of particular importance for individuals with metabolic diseases such as type 2 diabetes.

Type 2 diabetes arises from a combination of genetic susceptibility and environmental factors including physical inactivity and poor nutrition. 114 Thus, type 2 diabetes typically develops as individuals become more obese and less active, leading to insulin resistance, impaired glucose tolerance, and eventually, the onset of full blown type 2 diabetes. While type 2 diabetes is a multifactorial disease, it is a disease of altered carbohydrate metabolism on many levels. In people with type 2 diabetes, insulin levels are normal or high, but tissues such as liver, skeletal muscle, and adipose tissue become resistant to insulin. The pancreas compensates by producing large amounts of insulin, but this stress can eventually lead to pancreatic failure and the need for exogenous insulin treatment. The hyperinsulinemic state can result in impaired glucose transport into the liver, skeletal muscle, and adipose tissue. 115 While type 2 diabetes is usually adult-onset, the number of children and adolescents afflicted by this disease is dramatically increasing. In fact, there are currently 23.6 million people in the United States, which reflects approximately 8% of the population that have diabetes, a number that has doubled over the last 15 years and is continuing to increase at epidemic rates. 116

Although these statistics are discouraging, the good news is that regular physical exercise can delay or prevent the onset of type 2 diabetes. 117� Studies using randomized trials have found that lifestyle interventions, which included

150 min of physical activity per week, combined with diet-induced weight loss, reduced the risk of type 2 diabetes by 58% in an at-risk population. 91,117 Exercise interventions, independent of diet, have also been shown to be effective for the prevention and the progression of type 2 diabetes. 118 Exercise training in people with type 2 diabetes can improve blood glucose concentrations, body weight, lipids, blood pressure, cardiovascular disease, mortality, and overall quality of life. 121� The Look AHEAD study has demonstrated that combined weight loss and physical activity in people with type 2 diabetes causes modest weight loss of approximately 6%, improved glycolated hemoglobin, improved mobility, and improved kidney function but no improvement in cardiovascular disease over a 10-year period. 121,123,124,126 However, since the level of fitness was only assessed through year 4 of the study, conclusions on the effects of fitness level on cardiovascular disease cannot be made. 121,123,124,126 Increasing physical activity in adults with type 2 diabetes has been shown to result in partial or complete remission of type 2 diabetes in 11.5% of subjects within the first year of intervention, and an additional 7% had partial or complete remission of type 2 diabetes after 4 years of exercise intervention. 122 Taken together, all of these data show that the effects of exercise on carbohydrate metabolism have profound effects on metabolic health, and this knowledge is important as we work to address the epidemic of type 2 diabetes.