Cardio Exercise vs. Weight Lifting - Which is better for my health?

Back in the early 70's, Kenneth Cooper, M.D popularized the term "aerobics", which referred to the types of exercise that focused on cardiorespiratory fitness. This spurred on the jogging, cycling and walking craze which continues today. Aerobic exercise, also known as "cardiovascular" or "cardio" exercise, utilizes major muscles such as those in the arms and legs walking while increasing heart and respiratory rate. Examples of this type of exercise include jogging, aerobic dancing, rowing and bicycling. Since then Dr. Cooper's Aerobics Center and numerous other researchers have confirmed the health benefits of aerobic exercise which range from increased longevity to reduction in the risk of developing certain types of cancer and heart disease.  At the outset of the aerobics boom, resistance training or weight lifting was thought of as a means to building muscle mass, increasing strength or enhancing sports performance, but it took a back seat in terms of promoting general health. Over the past several years, this previously held perception is being reevaluated, with clear benefits being reported with resistance training in the literature.  This has led to a great deal of confusion among many people who want to do what is best for their health.   Additionally, for those with busy schedules, it is important to be able to get the "most bang for the buck" in terms of their time commitment to exercise.  In today's health tip, I'll try to point out some of the confirmed benefits of aerobic (cardio) and resistance exercise and also dispel some of myths surrounding each.


Effect on hypertension
Studies have shown that regular cardio exercise can reduce systolic blood pressure (the top number) anywhere from 4 to 9 mm (points).  The greatest benefit appears to come from a moderate-intensity exercise as compared to higher intensity workouts.  Some studies have also shown sustained improvement, although not as great as with cardio activity, in people participating in a resistance training program.  When lifting weights, systolic and diastolic blood pressures can actually increase temporarily, indicating the need for caution among individuals with uncontrolled hypertension or heart disease.  Resistance training does not, however, lead to the development of hypertension.

Effect on blood lipids
For some time it has been known that cardio exercise can increase the level of "good cholesterol" (HDL cholesterol) and lower blood triglycerides in those with elevated levels.  More recently it has been found that resistance training can bring about similar results.  It appears that the resistance programs that use lower weights with higher repetitions are the ones that are best at improving lipid profiles.  Combining aerobics with resistance training appears to be the optimal way to address elevated blood lipids.

Effect of oxygen uptake
In numerous studies, aerobic exercise has been confirmed to improve maximum oxygen uptake (VO2 max).  In sedentary persons, an improvement in VO2 max of 10-20% will occur with a minimum of 20 minutes of moderate-intensity aerobic exercise done at least 3 days a week.  Exercising at higher intensities will improve VO2 max even more. Typical resistance training programs that utilize "sets" of weight lifting with rest periods between have not demonstrated this same degree of improvement in VO2 max.  "Circuit training" programs, however, in which the individual moves rapidly between resistance exercises with minimal rest, have been shown to produce modest improvement in VO2 max.  These programs may be performed with exercise machines, hand-held weights, elastic resistance, calisthenics or any combination.

Effect on calorie burning
Exercise is an essential component of an effective weight loss program.  Aerobic activity alone, keeping caloric intake at the same level, causes weight loss primarily by "burning" body fat.  With diet alone, reduction in weight may occur, but this can be at the expense of lean body tissue (muscle).  A number off studies have shown that sustained weight loss is more likely when a reduced calorie diet is coupled with a regular exercise program. Resistance training programs (particularly those using circuit methods) have shown improvements in body weight and fat mass comparable to aerobic programs.

Effect on strength
This is one area where resistance training clearly stands out.  By pitting muscles against resistance, such as  a barbell or weight machine, the muscle cells eventually become larger and stronger.  When beginning resistance training, the initial increase in strength is due to a phenomenon called "neural adaptation." This means that the nerves servicing the muscles "fire" more frequently and more muscle fibers are recruited to perform the contraction.  Through neural adaptation, you become stronger, but the muscles remain the same size. With continued resistance training, the muscle cells eventually increase in size (hypertrophy).  While aerobic exercise does work the larger muscles of the arms and legs, its primary benefit is to improve heart and lung function.
 
Final thoughts
This Health Tip only touches on the many benefits of these two types of exercise.  The "take home" message is that there are clear and undeniable reasons to incorporate exercise into your life.  An ideal program should include elements of each type.  The American College of Sports Medicine recommends that all Americans should try to receive "30-60 minutes of moderate-intensity exercise (five days per week) or 20-60 minutes of vigorous-intensity exercise (three days per week) and perform strength training on two non-consecutive days each week."  From the above discussion, it is clear that there are complimentary benefits from participation in both types of exercise.

Sources for article:
Hypertension and weight training: secrets for success from The Cooper Institute
Exercises to Control Your Cholesterol from WebMD
How much am I burning? From Mayo Clinic
ACSM Issues New Recommendations on Quantity and Quality of Exercise from the American College of Sports Medicine

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Along Came a Spider...

Black widow spider (Latrodectus mactans)   The female black widow spider is a shiny, inky black spider that measures (including its legs) anywhere from one-half to one inch in length.  The male is much smaller and does not cause envenomation in humans.  The most distinguishing characteristic is a red to orange-colored marking on the underside of its abdomen in the shape of an hourglass.  Black widow spiders are found throughout the U.S. and prefer to live in undisturbed areas such as woodpiles, sheds, crawl spaces, basements and garages.  The venom of a black widow is a type of neurotoxin, meaning it attacks the nervous system. The bite is said to feel like a pinprick and sometimes the two fang marks can be seen.  Within a few hours, though, intense pain at the site of the bite begins. Systemic (affecting the entire body) symptoms of black widow envenomation include nausea, restlessness, sweating, increased blood pressure, severe abdominal pain, muscle spasms and fever. 

Brown recluse spider (Loxosceles reclusa) The brown recluse is named for its habit of hiding in dark locations such as attics, closets, and woodpiles.  Their range is primarily in the Midwest and South Central United States.  They are sometimes called "fiddle back" spiders due to a violin-shaped marking on their backs (cephalothorax).  This spider is golden brown in color and its size ranges from one-quarter to three-quarters inches in length. The bite produces a mild stinging, followed by local redness and intense pain within eight hours. The wound may take on a bull's-eye appearance, with a center blister surrounded by an angry-looking red ring and then a blanched (white) ring. Tissue at the site of the bite and the surrounding area dies and eventually sheds. Systemic symptoms include fever, chills, nausea, vomiting, and muscle aches.

What to do if bitten by a spider.  If it can be done safely, identification or collection of the spider can assist the doctor in managing the bite. First-aid measures for black widow or brown recluse bites include cleaning the wound, applying cool compresses and taking a mild pain reliever, such as acetaminophen (Tylenol).  Since the extent or seriousness of the envenomation may not be apparent shortly after the bite, it is a good idea to seek medical attention.  Development of systemic symptoms clearly warrants medical evaluation.
Most black widow spider bites do not cause serious complications and can be managed with pain medications, benzodiazepines (e.g. Valium) for muscle spasms and, administration of tetanus prophylaxis.

For more severe symptoms, such as increasingly severe pain, dangerously high blood pressure, and generalized muscle spasms, black widow antivenom is available. This should only be administered under the careful supervision of a physician since severe allergic reactions, including anaphylaxis, have occurred.
Rather than being toxic to the nervous system, the venom of the brown recluse primarily causes tissue destruction at the site of the bite.  With careful wound care, sometimes including treatment with antibiotics, most of these bites heal without complications. Often, weeks of treatment are necessary until the skin is completely healed.  Occasionally, because of severe tissue damage, surgical debridement or skin grafting may be required.

In spite of the general perception that spiders are dangerous, they are actually quite beneficial in controlling insects.  Most envenomations occur as a defensive measure when humans encroach upon the spider's habitat.  Spider-related fatalities are rare, usually only occurring in small children, the severely ill, or in the elderly. In fact, most people who go to the doctor because of a "spider bite" actually have some other skin problem.  Particularly in the areas of the country that venomous spiders are not known to live, a more likely explanation for a "spider bite" is a methicillin-resistant Staphylococcus aureus (MRSA) skin infection.

Sources for article:

Black widow spider from Medline Plus
Spider bites: First aid from Mayo Foundation for Medical Education and Research
Black Widow Spider Bite from WebMD
Brown Recluse Spider Bite from eMedicineHealth

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What is the difference between heart attack and heart failure?

The terms heart attack and heart failure are often confused.  While there is some overlap in both their symptoms and underlying cause, they are really two distinct entities.

Heart attack
A heart attack occurs when the flow of blood to an area of the heart is blocked.  Without a supply of oxygen-rich blood, the heart muscle dies.  Also known as myocardial infarction or MI, the Centers for Disease Control reports that 735,000 Americans experience heart attacks each year.

Most heart attacks develop in conjunction with coronary artery disease (CAD).  In CAD, a substance known as plaque gradually builds up in the arteries that supply the heart.  This disease process is known as atherosclerosis.  The combination of plaque formation along with a blood clot is the typical reason for blockage of the coronary artery causing the heart attack.

Prior to the complete blockage of a coronary artery, most people with narrowed coronary arteries will experience a symptom known as angina.  Angina occurs when the heart muscle is not being supplied with enough oxygen. It is usually described as a pressure or squeezing discomfort in the chest. This discomfort can also be felt in the arms (usually left), neck, or jaw.   Usually, this pain goes away with rest or after taking a medication to help improve blood flow to the heart muscle.

With complete blockage and death of the heart muscle (he
art attack) more severe symptoms typically occur. These symptoms include:

• Chest discomfort in the center of the chest that lasts for more than a few minutes, or goes away and comes back. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain.
• Discomfort in other areas of the upper body including one or both arms, the back, neck, jaw, or stomach.
• Shortness of breath, often occurring along with chest discomfort.
• Other symptoms may include breaking out in a cold sweat, nausea, or light-headedness.

A heart attack is a medical emergency causing over 370,000 deaths in the U.S. each year.

Heart Failure

When the term "failure" is applied to specific organs, e.g. kidney failure, liver failure, heart failure, etc., it conjures up thoughts of a final or terminal phase in the function of the organ.  In the case of heart failure, however, it does not mean that the heart has stopped working altogether; instead, it means that the heart's pumping power is weaker than normal. To compensate, the main pumping chambers of the heart (ventricles) become larger and the heart muscle thickens in order to maintain normal blood flow to the body. According to the American Heart Association, around 7.5 million Americans have some degree of heart failure which is one of the most common reasons for hospitalization among those over the age of 65.

One of the most common symptoms of heart failure is the buildup of fluid in various parts of the body. When this occurs, it is called congestive heart failure (CHF).   Symptoms of CHF vary, depending on whether the left or right chamber of the heart is primarily involved. With left sided heart failure, blood and fluid back up into the lungs causing shortness of breath, difficulty breathing when lying flat, and fatigue. With predominant right sided failure, blood and fluid back up causing swelling in the abdomen (ascites) and in the legs and feet (edema).

The most common reasons for developing heart failure include:

• Coronary artery disease which results in diminished blood flow to the heart muscle and heart damage.
• Heart attack with the development of "scar tissue" which interferes with the normal pumping action of the heart.
• High blood pressure which causes the heart to have to pump against higher resistance. Uncontrolled high blood pressure increases the risk of developing heart failure by two to three times.
• Disease or deformity of the heart valves. When the valves do not function normally, the heart muscle has to pump harder to keep the blood flowing as it should.
• Heart muscle disease (cardiomyopathy).  There are a number of causes for heart muscle disease including infections (e.g. viral myocarditis), alcohol abuse, and the toxic effect of certain medications including chemotherapy drugs.
• Congenital heart defects. These are problems affecting the heart's chambers or valves that are present at birth. If the heart and its chambers don't form correctly, the healthy parts have to work harder, which in turn may lead to heart failure.

In most instances, a heart attack is a life-threatening condition requiring emergency medical treatment. Likewise, when heart failure results from an acute event, such as a heart attack, immediate treatment is usually required.  More often, however,  heart failure, such as when it occurs in association with chronic hypertension, becomes more of a chronic, long-term condition.

Sources for article:
What is heart failure? from the American Heart Association
What is heart attack? from the National Heart, Lung, and Blood Institute

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