Tag Archives: fitness

Exercise, Part 9: Realistic Goals If You’re New to Exercise

FITNESS

Sustained physical activity requires that your heart pump blood to the lungs and to the exercising muscles.  The muscles extract oxygen, sugar, and other nutrients for use in chemical reactions that enable the muscle to keep moving (contracting).  To say that someone is physically fit simply means that the heart easily pumps a large volume of blood and the muscles extract and use nutrients very efficiently.  The heart, after all, is just a hollow muscle that pumps blood.  If you stimulate your heart muscle through exercise, it will become more powerful and able to pump more blood.  Regular sessions of physical activity increase the metabolic efficiency and power of your other muscles, too.  There are various degrees of fitness, with professional and Olympic athletes at the extreme upper end.

GETTING STARTED

I’ve had otherwise healthy overweight patients so “out of shape” that walking 20 yards to the mailbox was a real chore.  They were tired and panting when they got to the mailbox and had to rest a bit before returning to the house.  These folks are habitually sedentary and dramatically overweight.  But you need not feel too sorry for them.  After starting and maintaining an exercise program, these unfit people achieve the greatest degree of improvement in fitness level.  They make more progress, and faster, than those who begin with a greater level of fitness.

The way to achieve aerobic fitness is to regularly challenge your large muscles to perform sustained physical activity.  “Regularly” means at least four days a week, if not daily.  Left alone, your muscles don’t want to do much other than just get you through your day comfortably, without effort or aching or cramps.  You must challenge them to do more, work a bit harder, tolerate a little aching.  You’ll know you’re challenging them during exercise when you perceive that mild to moderate effort is required to keep the activity going.  You should be mildly short of breath, perhaps even perspiring lightly, yet still able to converse.  “Sustained” physical activity means at least 30 minutes in a day.  Most people find it a better use of their time to exercise for 30 minutes continuously rather than break it up into five or 10 minutes here and there.

Discontinuous activity (e.g., 10 minutes thrice daily) probably is just as good. If you think about it, there are many easy ways to increase your discontinuous physical activity. Consider taking the stairs instead of the elevator, parking far from the supermarket or workplace doors, walking the golf course instead of riding a cart.

(The exercise model above is “old school,” which isn’t necessarily good or bad.  Some newer scientific studies suggest that you can achieve comparable levels of fitness with much less time exercising, if you do it intensely.  An example is high-intensity interval training (HIIT).  That’s worth a blog post or two by itself.  I also leave strength training—also an important aspect of fitness—for another day.)

If you’re starting out in poor shape, you won’t be able to do 30 minutes of any exercise without adverse effects.  Don’t even try.  The worst thing you could do at this point is injure yourself or have such a horrible experience that you give up entirely.  Thirty minutes of daily activity is your goal to achieve over the next four to 12 months.  Moderate to high levels of fitness will take you six to 24 months.  The most important thing when getting started is to exercise at least a little, five to 10 minutes, on most days of the week.  And don’t overdo it in terms of intensity. Start low, go slow.  After three months, exercise will be a habit.  Prolongation of your exercise sessions will be easy as your amazing body responds gradually to the workload through the process called physical conditioning.

If walking 30 minutes daily is too hard for you at first, try walking just an extra 10 or 20 minutes daily.  If you can do that but it’s a bit of a strain, gradually (every two weeks) increase your walking time by five minutes daily until you are up to 30 minutes.  Average walking pace is 2 mph (3.2 km/h).  Once you can comfortably handle 30 minutes daily, the next step is to increase your walking pace to 3 or 4 mph (4.8–6.4 km/h) for the entire 30 minutes.  Four mph (6.4 km/h) is definitely a brisk walk.  It’s difficult for many people to sustain over 30 minutes until they work up to it gradually.  This is often done by walking at two paces, normal and brisk, during an exercise session.  You might walk five minutes at normal pace, then five minutes briskly, alternating every five minutes until the session is over.  Every two to four weeks, you can increase the minutes of brisk pace and taper off the normal pace.  You’re able to do this easily because your level of fitness is increasing.

I’m asking you to walk briskly (3–4 mph or 4.8–6.4 km/h) for 30 minutes most days of the week.  This brisk pace burns roughly 200 calories per session, in case you’re wondering.  If you eat a 400-calorie muffin, it provides enough energy for a one-hour brisk walk.  If you don’t burn the muffin calories as exercise or basal metabolism, they’ll turn into body fat.  (But you’re not eating muffins anymore, are you?!)

If you prefer physical activity other than walking, the general rule is to start slowly and gradually increase your effort (intensity) until you’re up to about 30 minutes of moderate-intensity exercise most days of the week.  Start low, go slow.

Steve Parker, M.D.

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Exercise, Part 2: The Fountain of Youth and Other Metabolic Effects

Part 1 of the Exercise series focused on how regular physical activity prevented or postponed death. Onward now to other benefits.

Waist Management

Where does the fat go when you lose weight dieting? Chemical reactions convert it to energy, water, and carbon dioxide, which weigh less than the fat. Most of your energy supply is used to fuel basic life-maintaining physiologic processes at rest, referred to as resting or basal metabolism. Basal metabolic rate (BMR) is expressed as calories per kilogram of body weight per hour.

The major determinants of BMR are age, sex, and the body’s relative proportions of muscle and fat. Heredity plays a lesser role. Energy not used for basal metabolism is either stored as fat or converted by the muscles to physical activity. Most of us use about 70 percent of our energy supply for basal metabolism and 30 percent for physical activity. Those who exercise regularly and vigorously may expend 40–60 percent of their calorie intake doing physical activity. Excess energy not used in resting metabolism or physical activity is stored as fat.

Insulin, remember, is the main hormone converting that excess energy into fat; and carbohydrates are the major cause of insulin release by the pancreas.

To some extent, overweight and obesity result from an imbalance between energy intake (food) and expenditure (exercise and basal metabolism). Excessive carbohydrate consumption in particular drives the imbalance towards overweight, via insulin’s fat-storing properties.

In terms of losing weight, the most important metabolic effect of exercise is that it turns fat into weightless energy. We see that weekly on TV’s “Biggest Loser” show; participants exercise a huge amount. Please be aware that conditions set up for the show are totally unrealistic for the vast majority of people.

Physical activity alone as a weight-loss method isn’t very effective. But there are several other reasons to recommend exercise to those wishing to lose weight. Exercise counteracts the decrease in basal metabolic rate seen with calorie-restricted diets. In some folks, exercise temporarily reduces appetite (but others note the opposite effect). While caloric restriction during dieting can diminish your sense of energy and vitality, exercise typically does the opposite. Many dieters, especially those on low-calorie poorly designed diets, lose lean tissue (such as muscle and water) in addition to fat. This isn’t desirable over the long run. Exercise counteracts the tendency to lose muscle mass while nevertheless modestly facilitating fat loss.

How much does exercise contribute to most successful weight-loss efforts? Only about 10 percent on average. The other 90 percent is from food restriction.

Fountain of Youth

Regular exercise is a demonstrable “fountain of youth.” Peak aerobic power (or fitness) naturally diminishes by 50 percent between young adulthood and age 65. In other words, as age advances even a light physical task becomes fatiguing if it is sustained over time. By the age of 75 or 80, many of us depend on others for help with the ordinary tasks of daily living, such as housecleaning and grocery shopping. Regular exercise increases fitness (aerobic power) by 15–20 percent in middle-aged and older men and women, the equivalent of a 10–20 year reduction in biological age! This prolongation of self-sufficiency improves quality of life.

Heart Health

Exercise helps control multiple cardiac (heart attack) risk factors: obesity, high cholesterol, elevated blood pressure, high triglycerides, and diabetes. Regular aerobic activity tends to lower LDL cholesterol, the “bad cholesterol.” Jogging 10 or 12 miles per week, or the equivalent amount of other exercise, increases HDL cholesterol (“good cholesterol”) substantially. Exercise increases heart muscle efficiency and blood flow to the heart. For the person who has already had a heart attack, regular physical activity decreases the incidence of fatal recurrence by 20–30 percent and adds an extra two or three years of life, on average.

Effect on Diabetes

Eighty-five percent of type 2 diabetics are overweight or obese. It’s not just a random association. Obesity contributes heavily to most cases of type 2 diabetes, particularly in those predisposed by heredity. Insulin is the key that allows bloodstream sugar (glucose) into cells for utilization as energy, thus keeping blood sugar from reaching dangerously high levels. Overweight bodies produce plenty of insulin, often more than average. The problem in overweight diabetics is that the cells are no longer sensitive to insulin’s effect. Weight loss and exercise independently return insulin sensitivity towards normal. Many diabetics can improve their condition through sensible exercise and weight management.

Miscellaneous Benefits

In case you need more reasons to start or keep exercising, consider the following additional benefits: 1) enhanced immune function, 2) stronger bones, 3) preservation and improvement of flexibility, 4) lower blood pressure by 8–10 points, 5) diminished premenstrual bloating, breast tenderness, and mood changes, 6) reduced incidence of dementia, 7) less trouble with constipation, 7) better ability to handle stress, 8) less trouble with insomnia, 9) improved self-esteem, 10) enhanced sense of well-being, with less anxiety and depression, 11) higher perceived level of energy, and 12) prevention of weight regain.

People who lose fat weight but regain it cite lack of exercise as one explanation. One scientific study by S. Kayman and associates looked at people who dropped 20 percent or more of their total weight, and the role of exercise in maintaining that loss. Two years after the initial weight loss, 90 percent of the successful loss-maintainers reported exercising regularly. Of those who regained their weight, only 34 percent were exercising.

 Part 3 of this series gets into specific exercise recommendations.

Steve Parker, M.D.

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Exercise, Part 1: Exercise Postpones Death

Earlier this month, many folks made New Years’ resolutions to start exercising in conjunction with their other resolution to lose excess weight. I’ve got bad news for them.

Exercise is overrated as a pathway to major weight loss.

Sure, a physically inactive young man with only five or 10 pounds (2 to 4 kg) to lose might be able to do it simply by starting an exercise program. That doesn’t work nearly as well for women. The problem is that exercise stimulates appetite, so any calories burned by exercise tend to be counteracted by increased food consumption.

"Should I go with aerobic or strength training....?"

On the other hand, exercise is particularly important for diabetics and prediabetics in two respects: 1) it helps in avoidance of overweight, especially after weight loss, and 2) it helps control blood sugar levels by improving insulin resistance, perhaps even bypassing it.

Even if it doesn’t help much with weight loss, regular physical activity has myriad general health benefits. First, let’s look at its effect on death rates.   

EXERCISE PREVENTS DEATH

As many as 250,000 deaths per year in the United States (approximately 12% of the total) are attributable to a lack of regular physical activity. We know now that regular physical activity can prevent a significant number of these deaths.

Exercise induces metabolic changes that lessen the impact of, or prevent altogether, several major illnesses, such as high blood pressure, coronary artery disease, diabetes, and obesity. There are also psychological benefits. Even if you’re just interested in looking better, awareness of exercise’s other advantages can be motivational.

Exercise is defined as planned, structured, and repetitive bodily movement done to improve or maintain physical fitness.

Physical fitness is a set of attributes that relate to your ability to perform physical activity. These attributes include resting heart rate, blood pressure at rest and during exercise, lung capacity, body composition (weight in relation to height, percentage of body fat and muscle, bone structure), and aerobic power.

Aerobic power takes some explanation. Muscles perform their work by contracting, which shortens the muscles, pulling on attached tendons or bones. The resultant movement is physical activity. Muscle contraction requires energy, which is obtained from chemical reactions that use oxygen. Oxygen from the air we breathe is delivered to muscle tissue by the lungs, heart, and blood vessels. The ability of the cardiopulmonary system to transport oxygen from the atmosphere to the working muscles is called maximal oxygen uptake, or aerobic power. It’s the primary factor limiting performance of muscular activity.

Aerobic power is commonly measured by having a person perform progressively more difficult exercise on a treadmill or bicycle to the point of exhaustion. The treadmill test starts at a walking pace and gets faster and steeper every few minutes. The longer the subject can last on the treadmill, the greater his aerobic power. A large aerobic power is one of the most reliable indicators of good physical fitness. It’s cultivated through consistent, repetitive physical activity.

Physical Fitness Effect on Death Rates

Regular physical activity postpones death.

Higher levels of physical fitness are linked to lower rates of death primarily from cancer and cardiovascular disease (e.g., heart attacks and stroke). What’s more, moving from a lower to a higher level of fitness also prolongs life, even for people over 60.

Part 2 of this series will cover all the other health benefits of exercise. Part 3 will outline specific exercise recommendations, such as the type and duration of activity.

Steve Parker, M.D.

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