Tuesday, November 15, 2011

Physical Activity and Heart Health

Physical Activity
Physical activity is any body movement that works your muscles and uses more energy than you use when you’re resting. Walking, running, dancing, swimming, yoga, and gardening are examples of physical activity.According to the Department of Health and Human Services’ “2008 Physical Activity Guidelines for Americans,” physical activity generally refers to bodily movement that enhances health. Exercise is a type of physical activity that’s planned and structured. Lifting weights, taking an aerobics class, and playing on a sports team are examples of exercise. Physical activity is good for many parts of your body. This text focuses on the benefits of physical activity for your heart and lungs.

Types of Physical Activity
The four main types of physical activity are aerobic, muscle-strengthening, bone-strengthening, and stretching. Aerobic activity is the type that benefits your heart and lungs the most.
This chapter contains text excerpted from “Physical Activity,” by the National Heart, Lung, and Blood Institute (NHLBI, www.nhlbi.nih.gov), part of the National Institutes of Health, May 2009, and from “Physical Activity and Weight Affect Coronary Heart Disease Risk,” by the National Institutes of Health (NIH,www.nih.gov), May 12, 2008.
Aerobic Activity
Aerobic activity moves your large muscles, such as those in your arms and legs. Running, swimming, walking, bicycling, dancing, and doing jumping jacks are examples of aerobic activity. Aerobic activity also is called endurance activity.
Aerobic activity makes your heart beat faster than usual. You also breathe harder during this type of activity. Over time, regular aerobic activity makes your heart and lungs stronger and able to work better.
Other Types of Physical Activity
The other types of physical activity—muscle-strengthening, bone-strengthening, and stretching—benefit your body in other ways. Muscle-strengthening  activities improve the strength, power, and endurance of your muscles. Doing pushups and sit-ups, lifting weights, climbing stairs, and digging in the garden are examples of muscle-strengthening activities.
With bone-strengthening activities, your feet, legs, or arms support your body’s weight, and your muscles push against your bones. This helps make your bones strong. Running, walking, jumping rope, and lifting weights are examples of bone-strengthening activities. Muscle-strengthening and bone-strengthening activities also can be aerobic, depending on whether they make your heart and lungs work harder than usual. For example, running is both an aerobic activity and a bone-strengthening activity.
Stretching helps improve your flexibility and your ability to fully move your joints. Touching your toes, doing side stretches, and doing yoga exercises are examples of stretching.
Levels of Intensity in Aerobic Activity
You can do aerobic activity with light, moderate, or vigorous intensity. Moderate- and vigorous-intensity aerobic activities are better for your heart than light-intensity activities. However, even light-intensity activities are better than no activity at all.
The level of intensity depends on how hard you have to work to do the activity. To do the same activity, people who are less fit usually have to work harder than people who are more fit. So, for example, what is light-intensity activity for one person may be moderate-intensity for another.
Light- and moderate-intensity activities:
Light-intensity activities are common daily activities that don’t require much effort. Moderate-intensity activities make your heart, lungs, and muscles work harder than light-intensity activities do.
On a scale of 0 to 10, moderate-intensity activity is a 5 or 6 and produces noticeable increases in breathing and heart rate. A person doing moderate-intensity activity can talk but not sing.
Vigorous-intensity activities:
Vigorous-intensity activities make your heart, lungs, and muscles work hard. On a scale of 0 to 10, vigorous-intensity activity is a 7 or 8. A person doing vigorous-intensity activity can’t say more than a few words without stopping for a breath.
Examples of Aerobic Activities
Below are examples of aerobic activities. Depending on your level of fitness, they can be light, moderate, or vigorous in intensity:
• Pushing a grocery cart around a store
• Gardening, such as digging or hoeing that causes your heart rate to go up
• Walking, hiking, jogging, running
• Water aerobics or swimming laps
• Bicycling, skateboarding, inline skating, and jumping rope
• Ballroom dancing and aerobic dancing
• Tennis, soccer, hockey, and basketball
Benefits of Physical Activity
Physical activity, especially aerobic activity, is good for your heart and lungs in many ways. The benefits of physical activity apply to people of all ages and races and both sexes.
Physical Activity Strengthens Your Heart and Improves Lung Function
Moderate- and vigorous-intensity physical activity done regularly strengthens your heart muscle. This improves your heart muscle’s ability to pump blood to your lungs and throughout your body. As a result, more blood flows to your muscles, and oxygen levels in your blood rise. Capillaries, your body’s tiny blood vessels, also widen. This allows them to deliver more oxygen to your body and carry away waste products, such as carbon dioxide and lactic acid.
Physical Activity Reduces Coronary Heart Disease Risk Factors
Moderate- and vigorous-intensity aerobic activity done regularly can lower your risk for coronary heart disease (CHD), also called coronary artery disease. CHD is a condition in which a fatty material called plaque builds up inside your coronary arteries. These arteries supply oxygen-rich blood to your heart.
Plaque narrows the coronary arteries and reduces blood flow to the heart. It also makes it more likely that blood clots will form in your arteries. Blood clots can partly or completely block blood flow. This can lead to a heart attack.
Certain traits, conditions, or habits may raise your risk for CHD. Physical activity can help control some of these risk factors:
• Physical activity can lower blood pressure.
• Physical activity helps improve and manage levels of cholesterol and other fats in the blood. Physical activity can lower triglyceride levels. Triglycerides are a type of fat. Physical activity also can raise high-density lipoprotein (HDL), or “good,” cholesterol levels.
• Physical activity improves your body’s ability to manage blood sugar and insulin levels. This lowers your risk for type 2 diabetes.
• Physical activity reduces levels of C-reactive protein (CRP) in your body. This protein is a sign of inflammation. High levels of CRP may raise your risk for CHD.
• Physical activity helps reduce overweight and obesity when combined with reduced calorie intake. Physical activity also helps you maintain a healthy weight over time.
• Physical activity may help people quit smoking. Smoking is a major risk factor for CHD. Inactive people are nearly twice as likely to develop CHD as people who are physically active. Studies suggest that like high blood cholesterol, high blood pressure, and smoking, inactivity is a major risk factor for CHD.
Physical Activity Reduces the Risk of Heart Attack
In people who have CHD, aerobic activity done regularly helps the heart work better. It also may reduce the risk of a second heart at- tack in people who already have had a heart attack. Vigorous aerobic activity may not be safe for people who have CHD. Talk to your doctor about what type of activity is safe for you.
Risks of Physical Activity
In general, the benefits of regular physical activity far outweigh risks to the heart and lungs.
Rarely, heart problems, such as arrhythmia, sudden cardiac arrest, or heart attack, occur during physical activity. These events generally happen to people who already have heart conditions. In youth and young adults, the risk for heart problems due to physical activity is higher in people who have underlying congenital heart problems. These are heart problems that have been present since birth. Congenital heart problems include hypertrophic cardiomyopathy, congenital heart defects, and myocarditis (inflammation of the heart muscle). People who have these conditions should talk to their doc-tors about which physical activities are safe for them. In middle-aged and older adults, the risk for heart problems due to physical activity is related to coronary heart disease (CHD). People who already have CHD are more likely to have a heart attack when they’re exercising vigorously than when they’re not.
The risk for heart problems due to physical activity is related to your fitness level and the intensity of the activity you’re doing. For example, someone who doesn’t do physical activity regularly is at higher risk for heart attack during vigorous activity than a person who is physically fit and regularly active.
If you have a heart problem or chronic (ongoing) disease, such as heart disease, diabetes, or high blood pressure, talk to your doctor about what types of physical activity are safe for you. You also should talk to your doctor about safe physical activities if you have symptoms such as chest pain or dizziness. Discuss ways that you can slowly and safely build physical activity into your daily routine.  
Recommendations for Physical Activity
The U.S. Department of Health and Human Services (DHHS) has released new physical activity guidelines for all Americans aged 6 and older. The “2008 Physical Activity Guidelines for Americans” explains that regular physical activity improves health. They encourage people to be as active as possible.
The guidelines provide specific recommendations about the types and amounts of physical activity that children, adults, older adults, and other groups should do. The guidelines also provide suggestions for how to fit physical activity into your daily life. The information in this portion of text is based on the new guide-lines from DHHS.
Guidelines for Children and Youth For children and youth, the guidelines advise the following:
• They do 60 minutes or more of physical activity every day. These activities should vary and be a good fit for their age and physical development. Children are naturally active, especially when they’re involved in unstructured play (like recess). Any type of activity counts toward the advised 60 minutes or more.
• Most physical activity should be moderate-intensity aerobic activity. Examples include walking, running, skipping, playing on the playground, playing basketball, and biking.
• Vigorous-intensity aerobic activity should be included at least 3 days a week. Examples include running, doing jumping jacks, and fast swimming.
• Muscle-strengthening activities should be included at least 3 days a week. Examples include climbing trees, playing tug-of war, and doing pushups and pull-ups.
• Bone-strengthening activities should be included at least 3 days a week. Examples include hopping, skipping, doing jumping jacks, playing volleyball, and working with resistance bands. Children and youth who have disabilities should work with their doctors to find out what types and amounts of physical activity are safe for them. When possible, these children should meet the recommendations in the guidelines.
Some experts also advise that children and youth reduce screen time because it limits time for physical activity. They recommend that children aged 2 and older should spend no more than 2 hours a day watching television or using a computer (except for school work).
Guidelines for Adults
For adults, the guidelines advise:
• Some physical activity is better than none. Inactive adults should gradually increase their level of activity. People gain some health benefits from as little as 60 minutes of moderate intensity aerobic activity per week.
• For major health benefits, do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity or 75 minutes (1 hour and 15 minutes) of vigorous-intensity aerobic activity each week. Another option is to do a combination of both. A general rule is that 2 minutes of moderate-intensity activity counts the same as 1 minute of vigorous-intensity activity.
• When doing aerobic activity, do it for at least 10 minutes at a time. Spread the activity throughout the week.
• For more health benefits, do 300 minutes (5 hours) of moderate- intensity aerobic activity or 150 minutes (2 hours and 30 minutes) of vigorous-intensity activity each week (or a combination of both). More physical activity will increase your health benefits.
• Muscle-strengthening activities that are moderate or high intensity should be included 2 or more days a week. These activities should work all of the major muscle groups (legs, hips, back, chest, abdomen, shoulders, and arms). Examples include lifting weights, working with resistance bands, doing sit-ups and push- ups, doing yoga, and doing heavy gardening.
Guidelines for Older Adults
For older adults, the guidelines advise:
• All older adults should avoid inactivity. Older adults who do any amount of physical activity gain some health benefits. If inactive, older adults should gradually increase their activity levels and avoid vigorous activity at first. You should follow the guidelines for adults, if possible.
• Older adults should do a variety of activities, including walking. Walking has been shown to provide health benefits and a low risk of injury.
• If you can’t do 150 minutes (2 hours and 30 minutes) of activity each week, be as physically active as your abilities and condition allow.
• You should do balance exercises if you’re at risk for falls. Examples include walking backward or sideways, standing on one leg, and standing from a sitting position several times in a row.
• If you have a chronic (ongoing) condition, such as heart disease, lung disease, or diabetes, talk to your doctor about whether you can do physical activity. Ask your doctor which activities are safe for you.
Guidelines for Women during Pregnancy and Soon after Delivery
For pregnant women and women who have recently given birth, the guidelines advise:
• You should talk to your doctor about safe physical activities to do during pregnancy and after delivery.
• If you’re healthy but not already very active, do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity each week. If possible, spread this activity across the week.
• If you’re already very active, you can continue being active as long as you stay healthy and talk to your doctor about your activity level throughout your pregnancy.
• After the first 3 months of pregnancy, you shouldn’t do exercises that involve lying on your back.
• You shouldn’t do activities in which you might fall or hurt yourself, such as horseback riding, downhill skiing, soccer, and basketball.
Guidelines for Other Groups
The guidelines also have recommendations for other groups, including people who have disabilities and people who have certain chronic conditions, such as osteoarthritis, diabetes, and cancer.
Physical Activity and Weight Affect Coronary Heart Disease Risk
Researchers have long known that both physical activity and excess weight affect the risk of coronary heart disease. However, it’s been hard to tease apart how much each contributes. A study found that being physically active can considerably, but not completely, lower the risk of cardiovascular disease associated with being overweight or obese. The research stems from the Women’s Health Study, begun in 1992 by NIH’s National Cancer Institute (NCI) and National Heart, Lung, and Blood Institute (NHLBI). Its original goals were to evaluate the effects of vitamin E and low-dose aspirin on cardiovascular disease and cancer in healthy women. Recognizing the value of the data they were collecting, the researchers extended the study to do more follow- up and evaluate other cardiovascular risk factors.
Dr. Amy Weinstein at the Beth Israel Deaconess Medical Center in Boston and colleagues at Brigham and Women’s Hospital analyzed data collected in the Women’s Health Study on almost 39,000 women who were 45 and older. They compared the participants’ body mass index (BMI—a ratio of weight to height) and physical activity levels at the start of the study with cardiovascular outcomes (such as heart attacks) over an average of 11 years of follow-up. In the April 28, 2008, issue of Archives of Internal Medicine , the researchers reported that the group had 948 cases of coronary heart disease during the follow-up period. The risk of coronary heart dis-ease, they found, increased as BMI increased. Obese women were over twice as likely to have a coronary event as women in the normal weight category.
Overall, the women who were physically active were 31% less likely to have coronary heart disease than those who weren’t active. After the researchers adjusted the data to account for other known influences—such as alcohol use, smoking, and diet—the physically active women still had an 18% lower risk of coronary heart disease. In particular, the researchers found that physical activity significantly reduced the risk of coronary heart disease in the overweight and obese women.
The researchers also looked at the time the women spent walking and found that the more the women walked, the lower their risk for coronary heart disease. The greatest drop, for each weight category, was between those who didn’t walk for exercise or recreation and those who walked 1–1.5 hours per week.
This study adds to a growing body of evidence showing that physical activity can help you live longer, regardless of whether you have excess weight. A half hour of moderate physical activity every day significantly reduces your risk of chronic disease, and more than 30 minutes further reduces the risk. Although walking and physical activity significantly reduced the risk of coronary heart disease among the overweight and obese women in this study, their risk didn’t drop as low as normal-weight women. Both weight control and physical activity are important for preventing coronary heart disease.

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