Archive for December 2013

This Is What Happens To Your Body When You Exercise

Whether you do it to lose weight, to reach a fitness goal or — dare we say it? — just for fun, exercise changes you. There’s the red face and the sweating, the pounding heart and pumping lungs, the boost to your alertness and mood, the previously nonexistent urges to talk about nothing but splits and laps and PBs. But while we all know that staying physically active is essential to a long, healthy, productive life, we don’t often understand exactly what’s happening behind the scenes.

We asked the experts to take us through — from head to toe — what happens in the body when we exercise. Neuroscientist Judy Cameron, Ph.D., professor of psychiatry at the University of Pittsburgh School of Medicine, Tommy Boone, Ph.D., a board certified exercise physiologist, and Edward Laskowski, M.D., co-director of the Mayo Clinic Sports Medicine Center spill the beans on what gets and keeps you moving.

Muscles

The body calls on glucose, sugar the body has stored away from the foods we eat in the form of glycogen, for the energy required to contract muscles and spur movement.

It also uses adenosine triphosphate, or ATP, but the body only has small stores of both glucose and ATP. After quickly using up these supplies, the body requires extra oxygen to create more ATP. More blood is pumped to the exercising muscles to deliver that additional O2. Without enough oxygen, lactic acid will form instead. Lactic acid is typically flushed from the body within 30 to 60 minutes after finishing up a workout. Tiny tears form in the muscles that help them grow bigger and stronger as they heal. Soreness only means there are changes occurring in those muscles, says Boone, and typically lasts a couple of days.

Lungs

Your body may need up to 15 times more oxygen when you exercise, so you start to breathe faster and heavier. Your breathing rate will increase until the muscles surrounding the lungs just can’t move any faster. This maximum capacity of oxygen use is called VO2 max. The higher the VO2 max, the more fit a person is.

Diaphragm

Like any muscle, the diaphragm can grow tired with all that heavy breathing. Some argue that as the diaphragm fatigues, it can spasm, causing a dreaded side stitch. (Others argue a side stitch is due to spasms of the ligaments around the diaphragm instead, while others believe the spasms to originate in the nerves that run from the upper back to the abdomen and arecaused by poor posture!) Deep breathing and stretching can alleviate the discomfort in the middle of a workout, and preemptive strengthening in the gym can ward off future issues.

Heart

When you exercise, heart rate increases to circulate more oxygen (via the blood) at a quicker pace. The more you exercise, the more efficient the heart becomes at this process, so you can work out harder and longer. Eventually, this lowers resting heart rate in fit people. Exercise also stimulates the growth of new blood vessels, causing blood pressure to decrease in fit people.

Stomach & Intestines

Because the body is pumping more blood to the muscles, it takes some away from the systems and functions that aren’t top priority at the moment, like digestion. That can result in tummy troubles. Movement, absorption and secretion in the stomach and intestines can all be affected.

Brain
Increased blood flow also benefits the brain. Immediately, the brain cells will start functioning at a higher level, says Cameron, making you feel more alert and awake during exercise and more focused afterward.

When you work out regularly, the brain gets used to this frequent surge of blood and adapts by turning certain genes on or off. Many of these changes boost brain cell function and protect from diseases such as Alzheimer’s, Parkinson’s or even stroke, and ward off age-related decline, she says. Exercise also triggers a surge of chemical messengers in the brain called neurotransmitters, which include endorphins, often cited as the cause of the mythical “runner’s high.”  The brain releases dopamine and glutamate, too, to get those arms and legs moving, as well as gamma-aminobutyric acid, or GABA, a prohibitive neurotransmitter that actually slows things down, to keep you moving in a smooth and controlled manner.

You’ll also likely feel better thanks to a bump in serotonin, a neurotransmitter well known for its role in mood and depression.

Hippocampus
This part of the brain is highly involved in learning and memory, and it’s one of the only sections of the brain that can make new brain cells. Exercise facilitates this, thanks to the extra oxygen in the brain. Even when you stop exercising, those new brain cells survive, whereas many other changes in the brain during exercise eventually return to their normal state should you become less active.

Hypothalamus
The hypothalamus is responsible for body temperature, as well as salt and water balance, among other duties. As your body heats up, it tells the skin to produce sweat to keep you cool.

Pituitary Gland
This control center in the brain alerts the adrenal glands to pump out the hormones necessary for movement. It also releases growth hormones. As the body searches for more fuel to burn after using up your glycogen stores, it will turn to either muscle or fat, says Cameron. Human growth hormone acts as a security guard for muscle, she says, telling the body to burn fat for energy instead.

Kidneys

The rate at which the kidneys filter blood can change depending on your level of exertion. After intense exercise, the kidneys allow greater levels of protein to be filtered into the urine. They also trigger better water reabsorption, resulting in less urine, in what is likely an attempt to help keep you as hydrated as possible.

Adrenal Glands
A number of the so-called “stress” hormones released here are actually crucial to exercise. Cortisol, for example, helps the body mobilize its energy stores into fuel. And adrenaline helps the heart beat faster so it can more quickly deliver blood around the body.

Skin

As you pick up the pace, the body, like any engine, produces heat — and needs to cool off. The blood vessels in the skin dilate, increasing blood flow to the skin. The heat then dissipates through the skin into the air.

Eccrine Glands
At the hypothalamus’s signal, one of two types of sweat glands, the eccrine glands, get to work. These sweat glands produce odorless perspiration, a mixture of water, salt and small amounts of other electrolytes, directly onto the skin’s surface. When this sweat evaporates into the air, your body temp drops.

Apocrine Glands
This second type of sweat gland is found predominantly in hair-covered areas, like the scalp, armpits and groin. These sweat glands produce a fattier sweat, typically in response to emotional stress, that can result in odor when bacteria on the skin begin to break it down, according to the Mayo Clinic.

Face

The capillaries close to the skin’s surface in the face dilate as well, as they strain to release heat. For some exercisers, this may result in a particularly red face after a workout.

Joints
Exercising puts extra weight on the joints, sometimes up to five or six times more than your bodyweight, says Laskowski. Ankles, knees, hips, elbows and shoulders all have very different functions, but operate in similar ways. Each joint is lined with cushioning tissue at the ends of the bones called cartilage, as well as soft tissue and lubricating fluid, to help promote smooth and easy motion. Ligaments and tendons provide stability.

Over time, the cushioning around the joints can begin to wear away or degenerate, as happens in people with osteoarthritis, the most common type of arthritis.

Staying active all day linked to healthy aging

Staying active all day linked to healthy aging

by Kathryn Doyle

NEW YORK (Reuters Health) – A generally active life, even without regular exercise sessions, was tied to better heart health and greater longevity in a study of older Swedes. Based on nearly 3,900 men and women over age 60 in Stockholm, the study adds to evidence suggesting that just sitting around may be actively harmful, researchers say.”We have known for 60 years that physical activity is important for the heart,” said lead author Elin Ekblom-Bak, of the Åstrand Laboratory of Work Physiology of the Swedish School of Sport and Health Sciences in Stockholm. But until recently the research has mainly focused on exercise and has “forgotten” about the background activity that we do during daily life, she told Reuters Health. Whether someone exercises vigorously or not, it still usually only takes up a small fraction of the day. That leaves the rest of the time for either sitting still or engaging in non-exercise activities, like home repairs, lawn care and gardening, car maintenance, hunting or fishing. For older people, who tend to exercise vigorously less than younger people, spending more time doing low-intensity activities like these could help cut down on sitting time, Ekblom-Bak and her colleagues write in the British Journal of Sports Medicine.

Between 1997 and 1999, more than 5,000 60-year-olds were invited to participate in the study, which began with a questionnaire about health history, lifestyle and daily activities, as well as medical tests and measurements.At the study’s outset, people who were more active on a daily basis, regardless of their exercise levels, tended to have smaller waists and healthier cholesterol levels. The participants were followed for the next 12.5 years. During that time nearly 500 people had a first-time heart attack or stroke, and nearly 400 people died from any cause. People who had reported high levels of daily non-exercise activity were less likely to suffer a heart-related event and less likely to die than those who were the least active. For every 100 people reporting low activity levels who had a heart attack or stroke, for example, only 73 highly active people experienced such events. For every 100 of the least active who died, only 70 of the most active did.

“These are fascinating findings,” said David Dunstan, of the Baker IDI Heart & Diabetes Institute in Melbourne, Australia, “but not really surprising since other studies that have looked at this from a different angle – that is, describing the detrimental relationship between excessive sitting and mortality outcomes – are essentially showing the same thing but in reverse because there is such a high correlation between sitting time and nonexercise physical activity behaviors.”

While sitting, muscles do not contract and blood flow decreases, which reduces the efficiency of many body processes, like absorbing glucose from the blood, said Dunstan, who studies heart health and exercise. Non-exercise activity likely prevents the general slowing-down associated with sitting, he told Reuters Health. “In addition to engaging in regular health enhancing exercise, people should be encouraged to also think what they do during the long periods in the day in which they are not exercising,” he said in an email. “Engaging in regular exercise is still important,” Ekblom-Bak said. “We saw that those who exercised regularly and that also had a daily physically active life had the lowest risk profile of all.” Moderate-to-vigorous exercise helps strengthen the heart muscle and other body muscles, and may help regulate blood pressure more than general activity, Dunstan said.

But it is important for doctors and society in general to promote daily activity, not just exercise, she said.

“Human beings are designed to move,” said Phillip B. Sparling, a professor of Applied Physiology and Health Behavior at the Georgia Institute of Technology in Atlanta who was not involved with the new study. “Ideally, we should have a mix of all levels of activity,” he said. “But, regardless of whether one exercises or not, the new message is to move more and sit less throughout the day.”

SOURCE: http://bit.ly/1gmmyCe British Journal of Sports Medicine, online October 28, 2013.

Endurance Exercise and Life Span

Is life expectancy affected if you do “extreme” exercise like ultramarathons and Ironman races?

“The short answer is, we don’t know,” said Dr. James O’Keefe Jr., the director of preventive cardiology at the St. Luke’s Mid-America Heart Institute in Kansas City, Mo., who has been studying the impact of long-term endurance training on longevity.

The relevant science is perplexing. A 2011 study of male, lifelong, competitive endurance athletes age 50 or older found that they had more scarring in their heart muscles than men of the same age who were active but not competitive athletes. None of the athletes had died young, however, and in a 2011 study of Tour de France riders, who train ferociously, those who had competed between 1930 and 1964 lived, on average, about eight years longer than age-matched men.

The pool of extreme, long-term endurance athletes available for scientific study is, however, tiny. So to gauge the impact of various amounts of training on life span, it is necessary, Dr. O’Keefe said, to turn to the rest of us, who exercise recreationally, if at all.

In the largest such study to date, involving more than 50,000 adults and presented at the 2012 annual meeting of the American College of Sports Medicine, participants who ran between 1 and 20 miles per week had almost 20 percent less risk of dying prematurely than people who didn’t exercise. But those who ran more than 20 miles per week enjoyed no such benefit. They had about the same risk of premature death as those who were sedentary.

Of course, individual genetics and lifestyle factors, such as a history of smoking and carousing, can play an outsize role in life span, Dr. O’Keefe said. Some 70-year-olds compete in repeated Ironman races with no apparent ill effects while some 40-year-olds suffer cardiac arrest during a marathon.

Over all, “my professional opinion is that if you are exercising to improve life expectancy and long-term cardiovascular health, be moderate about it,” Dr. O’Keefe said. “More,” for most people, “is not better.”