American Medical Association Family Medical Guide - American Medical Association [39]
The most important thing to remember when you are exercising or competing in an athletic event is to drink enough fluids. Water loss from breathing and perspiration can quickly dehydrate you, especially in hot or humid weather. Drink liquids before exercising, every 15 minutes during your workout, and for about 2 hours afterward. Water is the best thirst-quenching liquid, although sports drinks can replace the electrolytes lost during vigorous exercise. But be aware that many sports drinks contain a lot of sugar.
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Exercise, Fitness, and Health
If doctors could prescribe only one treatment to ensure a long, healthy life, it would be exercise. Regular exercise provides many health benefits, including a reduced risk of heart disease, high blood pressure, diabetes, some cancers, and most of the other common chronic diseases that can affect us as we age. The sedentary lifestyle of increasing numbers of Americans is a serious public health problem in this country. Even if you have been sedentary for years, it’s never too late to gain health benefits from exercise.
The Health Benefits of Physical Activity
The human body is designed for movement. We inherited the same efficient mechanisms our primitive ancestors needed for hunting food, traveling long distances on foot, and building shelter. Today, however, most of us drive our cars to the grocery store and sit in offices or classrooms for a large part of the day. Our lack of exercise triggers the processes that lead to common chronic diseases, including osteoporosis, heart disease, high blood pressure, type 2 diabetes, and cancer. Physical activity can help prevent these debilitating chronic diseases and keep you healthy in the following ways:
• Increases the efficiency of your heart and lungs.
• Raises the level of helpful HDL cholesterol and lowers the level of harmful LDL cholesterol in your blood.
• Helps you control your weight.
• Improves sleep.
• Reduces stress, improves your mood, and lowers your risk of depression.
• Boosts the strength and tone of your muscles.
• Builds strong bones.
• Increases the flexibility of your joints.
• Improves your self-image.
• Increases your energy level and endurance.
• Improves your posture.
• Slows the aging process.
• Improves your quality of life as you age.
Exercise also has beneficial effects on the brain. Physical exercise seems to stimulate the growth of brain cells, especially in an area of the brain called the hippocampus, which plays an important role in memory and learning. Physical activity also may improve the brain’s defenses against infection.
The Institute of Medicine has established exercise guidelines that set a goal of 1 hour a day of activity, including both low-intensity activities of daily life (such as walking or housecleaning) and more vigorous exercise (such as jogging, swimming, or cycling). If your job is sedentary, you can achieve this goal by, for example, walking at a pace of 4 miles per hour for a total of 60 minutes every day, or by engaging in a high-intensity activity such as jogging for 20 to 30 minutes 4 to 7 days a week. These guidelines are recommended for all children over age 6 and for all adults.
If you have been largely sedentary and start on a moderate exercise program, you can cut your risk of premature death in half. Spread short exercise sessions throughout your day, as long as the total adds up to about 60 minutes. For example, walk your dog briskly for 20 minutes in the morning and 10 minutes more at night. Add a 20-minute walk and a 10-minute stair-climbing session during your lunch hour and you’ve met your goal.
All types of physical activity are good for you and will lower