Frequently Asked Questions

We tried to answer some nagging questions about physical activity. If you can't find an answer to a question you have, write to us!

If I stop my physical activity, will my muscles turn to fat?

No, muscles cannot turn into fat, and fat cannot turn into muscle. If you stop your physical activity program, you will see a loss of fitness and strength. Half of the fitness gains you made will be lost in 1 to 3 months. The longer you trained, the longer it takes to lose the benefits.

Will missing an activity session periodically or reducing training temporarily affect endurance or strength?

No. Studies show that if intensity of training remains the same, fitness can be maintained even when the frequency of the activity is reduced for up to 15 weeks. Similar findings were found when strength training was studied. When strength training was reduced from 3 or 2 days per week to 1 day, strength was maintained for 12 weeks.

If I start a strength training program, how long will it be before I see a change in my strength?

Research shows that changes in the structure of your muscle can occur in as little as two weeks after starting a training program. How fast and how much you increase your strength depends on your initial level of strength and your potential for improvement. Increases in strength ranging from 2-9% per week have been observed.

How much activity is enough?

It depends on what your goals are. If you want to improve your fitness, aerobic activity 3 days per week of a moderate intensity for 20 to 60 minutes (either all at once or broken into segments) will be enough. But a well-rounded program that improves not only your fitness, but also your strength and flexibility is recommended. To improve your strength, add 2 to 3 days of strength training to your aerobic routine. And finish your aerobic and strength training activities with stretches to improve your flexibility.

Can increasing my physical activity alone help me lose weight?

If you don't change your calorie intake, increasing your activity alone can result in weight loss. Most controlled studies show a modest weight loss (usually 4 – 6 pounds) resulting from increasing activity alone. If you increase your activity and decrease the number of calories you take in, you will see a faster loss than with increasing activity alone. Starting an activity program during weight loss is essential, not only for the weight loss phase, but also (and more importantly) to maintain the loss.

I heard that stair climbing will make my rear end bigger. Is this true?

This is not true! Stair climbing does not make your buttocks bigger, especially if you maintain proper form. The exercise focuses mostly on the front of your thighs (quadriceps), as well as on your buttocks.

What does “overload” mean?

The overload principle refers to the workload or demand put on the body. The demand strains the body systems (cardiovascular, muscular, respiratory) in a good way. The body systems respond to the demand by adapting. This means that the heart will pump more blood, the muscles will become firmer and stronger, and the lungs will supply more oxygen. When you want to increase your fitness level or your strength, you have to provide this demand on your body systems to see them improve.

What is the “training-sensitive” zone?

This refers to the training intensity needed for improvement in fitness level. In general, the minimal training intensity threshold is 60% of maximum heart rate. You can calculate an estimate of your minimum threshold by using this formula: (220 - Your Age)  x  0.60 = target heart beats per minute. For example, if you are 30 years old, your minimum heart rate for improvement would be (220 – 30) x  0.60 = 114 beats per minute. This is how fast your heart should beat during activity to improve your fitness level. Initial level of fitness is an important consideration. For individuals who are more fit, an intensity level of 70% of maximum heart rate may be required to see improvements. Also, how long you do the activity can play a role. Improvement is similar for activities performed at a lower intensity if done for a longer period of time, as long as the total energy burned is equal. For example, suppose a person who runs for 30 minutes stimulates a training effect by working out at 70% of maximum heart rate. This person can also get a similar improvement by running at 60% of maximum heart rate for 40 minutes. Generally, lower exercise intensity can be offset by longer duration.

Why is it easier for guys to lose weight than it is for women?

Men have more muscle mass than women, especially in the upper body. Women usually have a greater percentage of body fat. Muscle is more metabolically active than fat, giving men a 5 – 10% higher metabolic rate than women. So men start out at an advantage — they burn more calories, even at rest.

I've heard that it doesn't matter how fat you are as long as you're fit — is this true?

Research has shown that a group of fat men who were fit were more likely to outlive thin men who were out of shape. So being thin is no substitute for being fit. Fat is a threat if it is located in your belly. If you also have other risk factors for disease like high blood pressure, high cholesterol, or high blood sugar, then its time to lose a few pounds in addition to getting fit.

I disagree with your BMI information. I have a BMI of 27 and a low body fat.

BMI (Body Mass Index) is a relationship between weight and height that has been found to correlate well with body fat in most adults. There are exceptions, however. BMI should not be used to assess competitive athletes and body builders because in these individuals, a high BMI can be due to a relatively great muscle mass. It sounds as though you fall into this category.

I have bad knees. What kind of activity is OK for me?

Swimming and other forms of water activity are ideal. You can burn considerable calories in the water without the negative impact on your legs.

I want to lose weight and see some changes in my body composition. What can I do?

Aim to burn between 1000 and 2000 calories per week with your activity program. You can do this by doing your activity on 3 to 4 days a week, burning 300 – 500 calories per session. Or, you may want to do your activity 4 to 5 days a week, burning 200 – 400 calories per session. Don't expect to see changes on the scale right away. Fat weight loss is a slow, steady process that can be obscured by an increase in lean weight.

Can you recommend any exercises to get rid of my sagging chin?

A sagging chin can be caused by a number of factors. Skin loses its elastic nature as we age and tends to sag. Also, your genes, cigarette smoking, and excessive sun exposure can all contribute to sagging skin. Unfortunately, while exercises for the neck will firm and tone the underlying muscles, they will not change the structure of the skin and make it more elastic.