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Understanding the Benefits of Aerobic Exercise
by Kathleen Ekdahl
When most of us think of health and fitness, we think first of aerobic fitness, the type of fitness associated with walking or running, swimming, biking or aerobics classes. While it is true that aerobic fitness, or cardiovascular endurance, is essential for an active, healthy life, we must also remember that cardiovascular endurance is but one part of a balanced fitness regimen. Your fitness program should always include strength training, flexibility training and healthy nutrition to safely and effectively reach your goals (see inset of related articles).
However, to include all these aspects of fitness can seem like a daunting task, and for many of us, our busy lifestyles only allow a short amount of time that we can devote to exercise. Consequently, the average American tends to focus primarily on activities that promote cardiovascular health, or the health of the heart and lungs, and this really does make sense given the tremendous health benefits of aerobic exercise.
First of all, we need to clearly define aerobic activities. Aerobic means "with oxygen" and aerobic exercise is defined as any long duration exercise of low to moderate difficulty using the large muscle groups of the body such as the legs, back, gluteals, arms, etc. When we say "long duration" we mean that in order to achieve the many benefits of aerobic exercise, we must usually sustain this activity for 20 minutes or longer. Activities that are very difficult, or "intense" and can only be sustained for brief periods of time (seconds to minutes), are usually anaerobic, or without oxygen, and do not necessarily produce the same benefits of aerobic exercise.
The benefits of aerobic exercise are myriad. They include systemic changes such as reduced cholesterol and blood pressure, improved muscular endurance, reduced body fat, increased metabolism, to name a few. Aerobic activities strengthen the heart and lungs, making them more efficient and durable, improving quality and quantity of life. Exercise not only extends your life, but also gives you more energy to live it to the fullest. Aerobic exercise improves the strength of your bones, ligaments and tendons, allows your body to use fats and sugars more efficiently, burns lots of calories and plays an important role in reducing the onset and symptoms of aging and illness. Aerobic exercise reduces your risk of heart disease, vascular disease and diabetes and can help those trying to quit smoking by relieving cravings and improving lung function. Research has confirmed that aerobic exercise reduces stress and combats depression as it raises self-esteem and physical awareness.
Given these incredible benefits, it’s a wonder that more Americans don’t exercise. Unfortunately, we know that less than 30% of all Americans exercise enough to improve their health and well being. Hundreds of thousands of Americans die each year from diseases that are caused by inactivity and poor cardiovascular health, and yet, even the fear of life threatening diseases is not enough to motivate us to exercise.

This national epidemic overburdens our healthcare system and costs the nation hundreds of millions of dollars each year. In response to this epidemic, the Surgeon General and The U.S. Department of Health and Human Services published a landmark report on the physical activity and health of United States citizens. It urges all Americans to incorporate "at least one half an hour of moderate-intensity physical activity on all, if not most, days of the week." While this may seem like quite a time commitment, the good news is that our definition of what constitutes moderate physical activity has broadened, making it easier for all of us to follow these recommendations. The Surgeon General’s Report lists many daily activities like gardening, cleaning the house, bowling, walking, or playing with the kids, as contributing towards the half-hour goal suggested. Activity can be broken up into shorter segments throughout the day, and we will still achieve many of the great benefits of exercise. The Surgeon General’s Report suggests that the less difficult the activity, the longer the overall duration needs to be, while very strenuous exercise can be shorter in time length. These recommendations give us all many activities to choose from, and there should be no excuse for not starting to exercise.

So now, we know we need to begin exercising. But, how you start, and what you start with depends on many factors such as current fitness level, history of medical problems and what your fitness goals may be. For example, the higher your current fitness level, the more exercise you can begin with, although all new exercisers may want to start with 20 minutes to one half hour of activity and then progress slowly up to 45 minutes or more of activity.

Slow progression is crucial
Slow progression is crucial to avoid the overuse injuries that can plague any fitness participant from the novice to even the most disciplined athlete.

Overuse injuries are injuries that most often occur when exercise progression is too fast or exercise technique is improper. These injuries may include shin splints, muscle tears, tendonitis, joint strain and a host of foot problems such as plantar fascitis and metatarsalgia, which can all sideline a fitness participant. Poor footwear, exercise surface and underlying orthopedic problems can all contribute to an increased likelihood of injury. Adjunct stretching and strength training reduces the risk of long term injuries.

The intensity, of difficulty, of exercise is another factor to consider when choosing an exercise program.  New exercisers should choose a lower intensity exercise like walking, before trying a high intensity exercise like running.   As time progresses, you can begin to increase the intensity of the exercise, for example progressing from walking to walk/run intervals- a great inbetween step before a complete run.  However, as exercise intensity increases, you may now need to decrease the duration of the exercise session or injuries may again arise.

Exercise participants should monitor their heart rates during exercise to make sure they are not exercising too hard or too easy. Exercise heart rates should remain in a "training zone" of between 55-85 % of your Estimated Maximum Heart Rate. The higher your initial fitness level, the higher your heart rate can increase without risk of "overdoing it". "Overdoing it" is a significant problem for new, overzealous exercisers. While we know that the more we exercise and the harder we exercise, the more energy we expend and the greater the potential benefits of exercise, there are without doubt upper limits to exercise. It is never necessary to push these upper limits.
"Rest is essential..." High intensity aerobic exercise performed 6 days a week will eventually lead to burnout, boredom and injury. A day or two of rest is essential so that muscles, tendons and ligaments have time to repair themselves and can continue to perform their important tasks.
Long-term exercise success depends on many factors; time management, injury prevention, inner motivation and realistic goal setting, to name a few. Success also greatly depends on exercise variety. The greater the exercise choices, the more likely you are to continue to find exercise enjoyable and fulfilling. Ultimate success, health and fulfillment only come from exercise that you find enjoyable and motivating. Always choose an exercise that you love!
This article provided courtesy of Kathleen Ekdahl.  Kathleen Ekdahl is an AFAA and ACE Certified Fitness Instructor and Personal Trainer with over 12 years experience in fitness and a background in Clinical Research and Cardiovascular Medicine. Kathy is a consultant and presenter for the fitness industry and fitness professionals.  

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Last Updated: March 5, 2006