Why is power now considered a health-related component of fitness?

A 2012 report by the independent Institute of Medicine (IOM) (Fitness Measures and Health Outcomes in Youth) provides evidence of the link between power and health. The IOM is a branch of the National Academy of Sciences. A panel of experts was selected by the IOM to review the literature on the relationship between health and the components of physical fitness. The report produced by the IOM committee indicates that power is associated with wellness, higher quality of life, reduced risk of chronic disease and early death, and better bone health. In fact, the association between power (and tests of power) and health among youth was judged to be stronger than the relationship between health and other components traditionally considered to be health related.


Fitness for Life previously listed power as a skill-related component of fitness. However, the fifth edition referred to power as a combined fitness component because power = strength × speed. Strength is a health-related component, and speed is a skill-related component. In the sixth edition of Fitness for Life, power has been added as a health-related component. The conclusions of the IOM report are supported by research indicating that power and activities that build power are associated with bone health in youth (Gunter et al., 2012). The authors of a more recent study (Janz, et al., 2015) indicated “…we think muscle power should be viewed as an important health-related physical fitness trait (in addition to a sport performance attribute)…., p. 2206.”  In another article Janz and Francis (2015) noted that they “….found strong and consistent associations as well as direct and indirect pathways, among muscle power, MCSA, and tibia strength. These results support the use of muscle power as a component of health-related fitness…., p.1.”


In 2014, authors from SHAPE America, Physical Best, Fitnessgram, Human Kinetics, and Fitness for Life prepared an article for JOPERD providing information about the inclusion of power as a health-related component of fitness (Corbin et al., 2014). More information on the topic, as well as other information about key fitness concepts, is provided in the JOPERD article and other sources cited in the reference list.



Corbin, C.B., Welk, G.J., Richardson, C., Vowell, C., Lambdin, D., & Wikgren, S. (2014). Youth physical fitness: Ten key concepts. JOPERD, 85(2), 24-31.


Gunter, K.B., Almsteadt, H.C., & Janz, K.F. (2012). Physical activity in childhood may be the key to optimizing lifespan skeletal age. Exercise and Sport Sciences Reviews, 40(1), 13-21.


Institute of Medicine. (2012). Fitness measures and health outcomes in youth. Washington, DC: National Academy of Sciences.


Janz, K. F. & Francis, S. L. (2015). Active voice: It’s a power thing: Muscle function, muscle size, and bone strength. Sports Medicine Bulletin, November 10, 1+.


Janz, K. F., Letuchy, E. M., Burns, T. L., Francis, S. L., & Levy, S. M. (2015). Muscle power predicts adolescent bone strength: Iowa bone development study. Medicine and Science in Sports and Exercise, 47(10), 2201-2206.

Why was cardiovascular fitness changed to cardiorespiratory endurance in the sixth edition of Fitness for Life?

A 2012 report by the independent Institute of Medicine (IOM) (Fitness Measures and Health Outcomes in Youth) recommended the use of the term cardiorespiratory endurance. The IOM is a branch of the National Academy of Sciences. A panel of experts was selected by the IOM to review the literature on the relationship between health and the components of physical fitness, and they chose the term cardiorespiratory endurance for several reasons.


Cardiorespiratory refers to the two systems of the body that are important in sustaining long-term physical activity (cardiovascular and respiratory), whereas cardiovascular refers to only one of the two systems. Endurance refers to the ability to persist in a performance for a long time, whereas fitness is a more general term. Together the terms cardiorespiratory and endurance were considered to be more descriptive than cardiovascular and fitness.


Recently authors from SHAPE America, Physical Best, Fitnessgram, Human Kinetics, and Fitness for Life prepared an article for JOPERD providing information about key fitness concepts. More information is in the JOPERD article cited in the reference list (Corbin et al., 2014). The article discusses the use of the term cardiorespiratory endurance.



Corbin, C.B., Welk, G.J., Richardson, C., Vowell, C., Lambdin, D., & Wikgren, S. (2014). Youth physical fitness: Ten key concepts. JOPERD, 85(2), 24-31.


Institute of Medicine. (2012). Fitness measures and health outcomes in youth. Washington, DC: National Academy of Sciences.

How does the Fitness for Life program fit into a school calendar?

Fitness for Life is adaptable to a variety of schedules, including regular schedules, block, A/B block, accelerated block, and yearly integrated plans. The base plan forFitness for Life uses a regular schedule. All other scheduling options are modifications of the base plan.


The base plan for Fitness for Life takes one semester (five class periods a week every week). That equates to 90 class periods of 40 to 50 minutes each. Some schools, however, integrate Fitness for Life into a one-year plan (approximately 180 class days).

In the base (one-semester) plan, students study one chapter per week. The program has 21 chapters, so schools may choose to use only 18 chapters or include two chapters a week for three weeks during the semester. While the one-chapter-per-week schedule provides the basis for planning, local schools may alter the plan based on local standards (focusing on content most appropriate for local standards) or modify the plan based on local school schedules. For example, schools using a one-year integrated plan typically cover one chapter every two weeks and integrate Fitness for Life content with traditional physical education content. The introduction available on the Teacher Web Resource provides information about a variety of scheduling options forFitness for Life programs.

What’s the difference between the test package and the premade quizzes available on the Teacher Web Resource?

In preparing the Teacher Web Resource for the sixth edition of Fitness for Life, the authors wanted to provide teachers with as many assessment options as possible. As noted in the evaluation section of the introduction on the Teacher Web Resource, constructing tests by using premade quizzes and constructing tests by using the test package each offer advantages, as described here:


Premade quizzes. A major advantage of premade lesson, chapter, and unit quizzes is that they evenly sample all content to be tested. Because they are already prepared, they can easily be printed or copied and require no extra work on the teacher’s part. Finally, teachers have several options when using the premade quizzes. It is not expected that all options will be used with all students. Teachers can decide which quizzes work best for each situation. Note that premade quizzes can be modified so that teachers can add, omit, or change questions as desired.


Tests constructed using the test package. The test package (TP) is for building custom quizzes or integrating quizzes with your learning management system (questions can be imported into the system). Custom tests created using the TP allow teachers to sample selected chapters and prepare a final exam that covers all chapters. Teachers who use chapters in an order other than the order presented in the book can create custom tests for the selected chapters. The TP is also useful for creating makeup tests with different questions than were on the original test.


Both premade quizzes and custom tests using the TP will test program outcomes, as outlined in the Teacher Web Resource.

Is a syllabus available for Fitness for Life?

Use the following link to download a sample syllabus for Fitness for Life. This editable sample is for a one-semester course that meets five days a week. However, it can be adapted for use in full-year or block classes. Syllabus preparation guidelines are included to allow instructors to customize the syllabus based on local standards and schedules.

Click here to view the syllabus.

How do I find the interactive iBook in the iBook store or iTunes?

The Fitness for Life interactive iBook works on iPads, so it’s best to use an iPad when searching for the book. Open the iBooks app, tap the Store button, and enter “fitness for life” in the search box. The first results should include the Fitness for Life interactive iBook (released July 15, 2014). Note that the results will include the updated fifth edition (released March 31, 2006), which is not interactive.

If you search the iBook store on a phone or other mobile device, the results might not include the interactive iBook because the product can’t be used on those devices.


You might be able to find the interactive iBook by searching iTunes on a laptop or desktop computer (or use this direct link:, but results may depend on whether you’re using a Mac or Windows system. Again, the best method is to search from your iPad, because that’s the device that will run the interactive iBook.

What is the difference between cardiorespiratory endurance and aerobic capacity?

The Institute of Medicine (2012), in its report titled Physical Fitness and Health Outcomes in Youth, recommended the term cardiorespiratory endurance for use in assessing health-related fitness with youth. Consistent with that report, Corbin and colleagues (2014, p. 28) noted the following:


Cardiorespiratory endurance is the recommended term for the fitness component frequently described as cardiovascular fitness, aerobic fitness, cardiorespiratory fitness, or cardiovascular endurance. Numerous terms are used to describe the component of fitness associated with functioning of the cardiovascular, respiratory, and muscular systems. However, there are subtle differences in meaning and interpretation among these different terms. For field measures, the IOM (2012) recommends the definition by Saltin (1973); cardiorespiratory endurance is “the ability to perform large-muscle, whole body exercise at a moderate to high intensity for extended periods of time” (IOM, 2012, p. 1-2). The term cardiorespiratory endurance, and its definition, is appropriate for use in fitness education because it reflects the ability of a person to perform functional fitness activities of daily life associated with the three principal systems supporting performance (cardiovascular, respiratory, muscular).


Corbin and colleagues (2014, pp. 28-29) further indicated the following:


Performance on the commonly used PACER test, for example, reflects cardiorespiratory endurance since it directly relates to the ability to sustain aerobic activity over an extended period. Lap scores on the PACER provide baseline information for both health information (where you stand in terms of health) and functional information (how much you can do and if you are getting better) and are useful in personal program planning. Lap scores can also be converted to estimates of aerobic capacity, but the raw lap scores provide unique meaning about functional fitness. The mile run test also can reflect cardiorespiratory endurance, but it is not as widely used (or endorsed) due to the issues with motivation and pacing. The walk test, a test option offered in FG, provides an alternative assessment of cardiorespiratory endurance that has particular utility for youth with low fitness, special needs, and those who are just beginning physical activity.


While cardiorespiratory endurance and aerobic capacity are commonly considered to be synonyms, for educational purposes it is appropriate to differentiate between the two. Cardiorespiratory endurance is measured by field tests and reflects both health and functional fitness. Aerobic capacity, in contrast, reflects the overall capacity of the cardiovascular and respiratory systems, but not necessarily functional fitness.


Aerobic capacity reflects the maximal amount of oxygen that can be taken in and used by the body. It is typically expressed as maximal oxygen uptake (VO2max) and VO2max is generally considered to be the best measure of aerobic capacity. Because differences in body size can influence oxygen uptake (i.e., bigger people have more body tissue and use more oxygen), the measure of aerobic capacity is most commonly expressed relative to body weight or milliliters O2 consumed per kilogram of body weight per minute (ml/kg/min or mL/kg-1/min-1).


In summary, cardiorespiratory endurance is the preferred term for use in health-related fitness field testing of youth when referring to the ability to sustain aerobic exercise for a long period.  Aerobic capacity refers to the amount of oxygen that can be used in maximal exercise.  Tests of aerobic capacity are typically done in a laboratory setting. Aerobic capacity scores are used to validate tests of cardiorespiratory endurance; these scores can be estimated from scores on field tests (see the next question in this FAQ).




Corbin, C.B., Welk, G.J., Richardson, C., Vowell, C., Lambdin, D., & Wikgren, S. (2014). Youth physical fitness: Ten key concepts. JOPERD, 85, 2, 24-31.


Institute of Medicine. (2012). Fitness measures and health Outcomes in youth. Washington, DC: National Academies Press.

How do you convert cardiorespiratory fitness scores (PACER laps and time for the mile run) into aerobic capacity scores?


Several formulae have been developed for converting field test scores of cardiorespiratory endurance into aerobic capacity scores. Until recently, Fitnessgram used a formula that included field test scores, age, gender, and BMI to determine aerobic capacity (VO2max).


Fitnessgram now uses a more recently developed formula for converting PACER laps (cardiorespiratory endurance scores) into aerobic capacity scores. Tables have been developed to simplify the conversion (they use a table rather than a formula). These tables are available at



The new PACER conversion tables (FG 10.0) do not use BMI. This solves problems associated with the previous tables related to BMI. Now youth of the same age use the same lap scores to convert to aerobic capacity. The tables for FG9 are still used for converting mile run scores to aerobic capacity. A new formula for converting mile run scores to aerobic capacity is under development.



Current equation for converting PACER laps to aerobic capacity:


VO2max = 45.619 + (0.353 * PACER laps) − (1.121 * age)

I read that physical exercise protects against cognitive decline and improves brain function. Do you agree? Why or why not ?

I agree that exercise protects against cognitive decline and improves brain function. A recent report from the Centers for Disease Control and Prevention (CDC) provides ample evidence that for people of all ages, including middle school students, exercise benefits cognitive performance. School-aged youth who get regular physical activity and physical education score better on academic tests, and adults who exercise are at lower risk of diseases such as Alzheimer's than adults who do not exercise. The link to the CDC report and other references to support this point of view are provided below.

Do you know of any negative effects of exercise on the brain ?

I do not know of any negative effects of exercise on the brain.

I read in the newspaper that the government has rules for how much exercise teens should do. Is this true?

You are correct. Physical activity guidelines (rules) for Americans were published on October 7, 2008. These guidelines were published by the United States Department of Health and Human Services (DHHS). The new guidelines are especially important because they are the first guidelines to cover all age groups from children through senior adults. They include guidelines for teens.

Fortunately, the authors of Fitness for Life planned ahead, and the information in your textbook is consistent with the new guidelines. So if you use the information in your textbook when you plan an activity program, you will meet the new guidelines for teens. The new guidelines for teens are included in the following table. You can learn more about them at

Physical Activity Guidelines for Children and Teens (Ages 6-17)

Amount of time One hour (60 minutes) or more each day
Aerobic activity Moderate activity (such as brisk walking) should be done daily, and vigorous activity (that makes your heart beat faster such as jogging or playing active games) should be done at least 3 days a week. Moderate and vigorous activity can be combined to earn the 60 minutes of daily activity.
Muscle fitness activity, including exercises to strengthen muscles and bones Exercises to build the muscles and bones (such as elastic band resistance exercises or fitness calisthenics) should be performed at least 3 days a week.

U.S. Department of Health and Human Services. 2008. Physical activity guidelines for Americans. Available at

Is plyometric exercise such as jumping over smaller boxes (roughly 12 inches high) appropriate for middle school children after they have been in PE for 8 weeks or more?

Until the 1990s strength and power training was typically not recommended for youth (children or adolescents) because of fear of injury. Research conducted in recent years indicates that most injuries occur as a result of inappropriate use of equipment and lack of qualified supervision. In 2009 the National Strength and Conditioning Association published a position paper on youth resistance training. The reference to this position paper is at the end of this answer.

Plyometrics is one of many types of resistance training. It involves the use of an eccentric muscle action in which the muscle lengthens followed by a concentric muscle action in which the muscle shortens. Think about a basketball player who attempts to block a shot during a game. The player bends her knees and hips as she lowers her body (eccentric phase) and then jumps up as quickly as possible to block the shot (concentric phase). Children do plyometrics when they jump rope or play hopscotch. Plyometrics is not limited to jumping; it can be done with the arms as well as the legs and is most effective for improving power (strength × speed). Done properly, resistance training, including plyometrics, can be safe and beneficial for children and adolescents (see reference).

So is jumping over small boxes (about 12 inches high) appropriate for middle school youth who have been in physical education for several weeks? The position paper on youth resistance training suggests “that you begin with a light load and progress the training program depending on needs, goals, and abilities. Listening to the needs and concerns of individuals is essential” (page S62).

Avery Faigenbaum, senior author of the position paper on youth resistance training, indicates, “While plyometric training that is sensibly progressed over time has been found to enhance movement biomechanics and improve functional abilities in school-age youth, injuries can occur if the intensity, volume, or frequency of training exceed the abilities of the child. The key is proper instruction on both jumping and landing mechanics, which should be part of PE.”

So what is appropriate for one youth might not be for another. If power is a goal, plyometric exercise such as jumping over 12-inch obstacles (preferably not boxes) could be appropriate for some young athletes who have participated in a progressive plyometric training program, but this type of exercise will likely be too intense for most middle school students in PE. It depends on individual abilities, training experience, and the quality of the movement. The use of elastic cords set at varying heights or different-sized cones would be safer, and the height could be adapted to the needs of the individual.

Reference: Faigenbaum, A.D., et al. 2009. Youth resistance training: Updated position statement paper from the National Strength and Conditioning Association. Journal of Strength and Conditioning Research 23(supplement): S60-S79.

Skateboarding is my favorite activity. Is skateboarding a good activity for building physical fitness?

Skateboarding can be a very good activity for building physical fitness and for meeting national physical activity guidelines. Skateboarding requires balance, agility, and coordination, all parts of skill-related physical fitness. Depending on how you do it, it can build different parts of health-related physical fitness, too. For example, if skateboarding increases your heart rate into the target zone and keeps your heart rate elevated (see page 41 of the Fitness for Life: Middle School text or page 165 of the Fitness for Life, Sixth Edition high school text), it builds cardiorespiratory fitness. It can also contribute to muscle fitness and flexibility. To build muscle fitness in both legs, you should alternate the pushing leg.

We pictured skateboarding on the cover of Fitness for Life: Middle School because it can be a good activity for teens. Meg Greiner, a National Physical Education Teacher of the Year, now teaches skateboarding at her school in Oregon. Many others teach skating activities as well. However, skateboarding can be dangerous if safety precautions are not taken. Proper safety equipment such as a helmet, knee pads, and wrist and hand pads should be used. Finding a safe place to do boarding activities is also important. Many communities are now building special skateboard facilities so that teens have a safe place for skateboarding.

Can girls build big muscles if they do muscle fitness exercises?

Sometimes girls worry about doing exercises for muscle fitness because they are afraid that they will build big muscles. It is true that muscle fitness exercises cause muscles to get bigger for both boys and girls. But it is also true that most girls will not be able to build muscles as big as boys can. During the teen years and into adulthood, the body produces more of the hormone that causes the body to build muscle than it does during childhood. But males get much more of that hormone than females. That is why males develop bigger muscles than females do. Most experts, and most girls and women who have done regular exercise, agree that building muscles helps you look your best because muscles keep your abdomen from protruding and help you to look firm and fit. Muscle fitness provides many benefits other than feeling and looking your best.

I read that physical exercise protects against cognitive decline and improves brain function. Do you agree? Why or why not?

The authors agree that exercise protects against cognitive decline and improves brain function. A report from the Centers for Disease Control and Prevention (CDC) provides ample evidence that for people of all ages, including middle school students, exercise benefits cognitive performance. School-aged youth who get regular physical activity and physical education score better on academic tests, and adults who exercise are at lower risk of diseases such as Alzheimer's than adults who do not exercise. Use this link to access the CDC report:

Do you know of any information that would support or oppose my hypothesis that exercise will positively affect concentration in children?

This quote from the CDC provides an answer to your question: "Student physical activity may help improve academic performance including academic achievement (e.g., grades, standardized test scores); academic behavior (e.g., on-task behavior, attendance); and factors that can positively influence academic achievement (e.g. concentration, attention, improved classroom behavior). This report is a literature review that examines the existing research on the relationship between school-based physical activity, including physical education, and academic performance. It spans 23 years of research and includes 50 studies. The majority of the studies in this review report that physical activity was positively related to academic performance. Most importantly, adding time during the school day for physical activity does not appear to take away from academic performance. Schools should continue to offer and/or increase opportunities for student physical activity."

Is the BMI (body mass index) a good indicator of body composition and body fatness?

The body mass index (BMI) uses a formula that includes height and weight. It is often used in research because it requires measurements that are easy to get (height and weight). Because it is easy to measure and does not require a lot of equipment, BMI can be easily assessed for large numbers of people. Still, the BMI has its limitations as a method of assessing body composition and body fatness. Both the BMI and height–weight charts have the problem of classifying some muscular people as overweight when they really are not. This is because people who have a lot of muscle can be high in weight without having too much body fat. This is a good reason for making many assessments for body composition, including measurements such as skinfolds as shown in the Fitness for Life textbooks. These measurements are a more accurate indicator of body fatness than BMI. To review information on BMI and other measurements, refer to lesson 8.1 of the Fitness for Life: Middle School textbook and lesson 13.1 of the Fitness for Life, Sixth Edition high school textbook.

I want to keep track of the steps I take each day. How many steps should a seventh-grader take?

The national physical activity guidelines for youth indicate that people your age need 60 minutes to several hours of physical activity each day. The guidelines do not suggest a specific number of steps. However, using a pedometer to count steps (see page 29 of the middle school book) can be a good way to self-monitor (keep track of) your daily activity.

A study of youth found that younger middle school boys average about 13,000 steps a day while younger middle school girls average about 11,000 steps a day. Older middle school boys (11,000 steps per day) and girls (10,000 steps per day) average fewer steps per day than younger middle school youth. You can earn the President’s Council on Physical Fitness and Sports Active Lifestyle Award by taking 12,000 steps per day for five days a week for six weeks (see

Most experts agree that you should not start by setting high goals such as those for the Active Lifestyle Award. The best way to start is to using a pedometer to keep a record of the steps you take each day for one week. At the end of the week, determine your average steps per day. Then set a goal for the next week of 1,000 more steps per day than the average of the week before. You can continue to increase each week until you average about 12,000 steps or higher. When you get close to taking 12,000 steps a day, you may want to consider trying to earn the Active Lifestyle Award.

Is participation in many sports healthy?

National physical activity guidelines for children and teens recommend at least 60 minutes of moderate to vigorous physical activity each day. Guidelines from SHAPE America indicate that several hours of appropriate activity can be beneficial to fitness and health.

So being involved in several sports can be beneficial. Learning skills in one sport can transfer to other sports and make them easier to learn. For example, learning how to serve a tennis ball can help you learn how to spike or serve a volleyball. Also, learning many sports can be useful later in life because people who have skills in many activities have more options for participation.

However, even a good thing such as being physically active can be harmful if overdone. Experts have identified problems with overtraining. Overtraining means doing so much activity that you don’t enjoy it anymore and feel fatigued even when you are not participating. We also know that too much activity in hot or cold temperatures can be harmful. Finally, too much of a certain activity can cause harm. For example, pitchers in youth baseball are limited in the number of pitches that they can throw each week because too much throwing can cause damage to the elbow.

The key is to listen to your body. Report problems to parents or other responsible adults. “No pain, no gain” is not correct. Pain is not necessary for achieving good performance in sports; it’s actually your body’s way of warning you that you have a problem.

It is OK to play several sports throughout the year. It is also OK to participate in more than one sport at a time. For example, you might play baseball on a team and practice playing soccer. However, if the combined activities take more than a couple of hours a day and if they are so vigorous that they cause you pain and excessive soreness, you are doing too much. Also listen to your “fun meter.” If your involvement in sports starts to seem like work rather than play, it may be time to make some adjustments.

Before starting on any sport program that involves regular sessions of vigorous physical activity or physical contact, you need to have a good medical examination to make sure that you are ready for the activity. Many school sports require a physical exam before you can participate. Participation also typically requires the consent of a parent or responsible adult.

I’ve heard that eating protein builds muscles and that eating fat makes you fat. Is this true?

The nutrients that provide energy to your body are carbohydrate, protein, and fat. For good health, you should eat foods that include all of these nutrients. National nutrition guidelines recommend that your diet include 45 to 65 percent of calories from carbohydrate, 10 to 35 percent of calories from protein, and 20 to 35 percent from fat.

So, carbohydrate is the type of foods that will be the biggest part of your diet. Carbohydrate includes basic foods such as grains, vegetables, and fruits. Protein, such as milk products, meats, nuts, and beans, also provides energy and are necessary for building body tissue such as muscles and bones. So it’s true that protein is important for building muscles in the body. But it’s important to know that eating protein above the recommended level (10 to 35 percent of your daily calories) does not cause extra muscle growth. Too much protein in the diet (more than 35 percent) can actually cause the body harm. Also, eating protein without doing muscle fitness exercise does not cause strength and muscular endurance above normal amounts. So regular exercise is especially important in building muscles.

Fat is also a source of energy. Certain types of fat (such as fish oil) are good for you, but some (such as saturated fat in butter) are not so good, and you should limit the amount you eat (see page 100). One gram of fat contains 9 calories, and one gram of carbohydrate or protein contains 4 calories. In other words, if you ate the same amount of fat as you ate of carbohydrate or protein, you would take in more than twice the calories. Therefore, it’s important to limit fat in the diet, especially saturated fat. But some fat is necessary for good health.

The key to having a healthy body weight is energy balance. This means taking in no more calories than you expend (such as by doing regular exercise). It’s true that if you eat a lot of fat, you will take in more calories and will have a harder time doing enough activity for energy balance. But all calories consumed in your diet, not just fat calories, are important. So be sure to eat all types of food for energy, but keep the total calories in your diet equal to the total calories that you burn in activity.

Is there such a thing as too much practice?

Yes, there is such a thing as too much practice. Perfect or good practice helps you learn skills. Practicing or repeating a skill the wrong way doesn’t help because you’re learning the skill incorrectly. If you practice for too long all at once, you can become fatigued, and your good practice turns into bad practice. When you get tired, you start to make mistakes, and that makes your practice ineffective. Also, if you get bored with practice, you might start to practice a skill incorrectly.

This doesn’t mean that you should always stop practicing when you get tired. During a game, you often have to perform skills when you’re tired. For example, late in a basketball game, you might have to shoot when you’re tired. So practicing shooting when you’re a bit tired can help you shoot well in a game when you’re tired.

The important thing to remember is to focus on good practice when you start to get tired or bored. If the practice is not good practice, find a way to practice correctly or stop the practice until you can concentrate better. Practicing one skill for a while and then another for a while can help you keep from getting bored and can help you practice well, even when you’re tired. However, if you’re too tired to practice properly, stop your practice and try again at another time.

Why do you recommend 10 to 15 repetitions for muscular strength and 11 to 25 reps for muscular endurance for middle school–aged youth?

The overload principle (described on page 79 of the middle school textbook and on page 93 of the high school textbook) provides the basis for determining the amount of exercise necessary for building muscle fitness. The amount of resistance exercise recommended for building muscle fitness varies depending on age. ACSM's Guidelines for Exercise Testing & Prescription, which provides recommendations for adults, notes that 3 to 6 repetitions of heavy resistance can be used at one extreme, and more repetitions at lighter resistance (8 to 12) can be used at the other extreme (ACSM 2014). The guidelines suggest that to elicit improvement in both muscular strength and endurance, 8 to 12 repetitions at an intensity that results in muscular fatigue is recommended for healthy adults. For youth, the general recommendation is that lighter resistance (weight) be used, especially for younger teens. A summary of the literature by Faigenbaum resulted in the recommendation of 10 to 15 repetitions for youth rather than 8 to 12 as recommended for adults. For exercises that use body weight as resistance, such as curl-ups and push-ups, or exercises with very light resistance, up to 25 repetitions can be used (with a focus more on muscular endurance than strength). More than 25 repetitions of an exercise would be possible only with very low resistance and would be of limited value for building muscle fitness. If muscle fitness is the goal, fewer repetitions with a higher resistance is recommended.

Of course, depending on a person's level of fitness, the amount of resistance training will vary. For example, it is recommended that teens who are beginning resistance training start with lower resistance and a higher number of repetitions. As individuals gradually improve (principle of progression; see page 80 of the middle school textbook), the amount of resistance and the number of repetitions will typically change. More advanced exercisers and older teens will typically use greater resistance and fewer repetitions (see the sixth edition of Fitness for Life for high school students).

American College of Sports Medicine. (2014). ACSM's guidelines for exercise testing & prescription (9th ed.). Philadelphia: Lippincott Williams & Wilkins.

Corbin, C.B., and R. Lindsey. (2013). Fitness for life (6th edition). Champaign, IL: Human Kinetics.

Faigenbaum, A.D. (2003). Youth resistance training. President's Council on Physical Fitness and Sports Research Digest 4(3): 1-8.

You sometimes use the word exercise and sometimes use physical activity. Aren’t these two the same thing?

The terms exercise and physical activity have very similar meanings. However, experts now agree that physical activity is a term that has a much broader meaning than the word exercise. Physical activity includes many types of activity, such as exercise, sports, dance, recreational activities, and lifestyle activities. Exercise is one type of physical activity that is primarily used to build physical fitness. For example, muscle fitness exercises are referred to as exercises because they are designed especially for building muscle fitness. These and other exercises (such as flexibility exercises) are types of physical activity but are also considered exercise. Sports and dance are also types of physical activity but are not generally classified as exercise. Sports and dance could be done for fitness but are also frequently done for other reasons, such as having fun and being with friends. Some people do not understand the difference in terms, so it is not unusual to see the terms used interchangeably.

How often do experts suggest that teens do muscle fitness exercises?

The general recommendation for muscle fitness exercises for teens depends on several factors. First, it is important to know whether you want to build muscular endurance or muscular strength. Second, it is important to know your age. Finally, it is important to know if you are a beginner or a person who has been doing regular muscle fitness exercise. Strength exercises should be performed two or three days a week and not on consecutive days. For muscular endurance, the exercises can be done three to six days a week. For preteens (11 to 12), younger teens (13 to 14), and older teens who are just beginning, two days a week would be a good place to start. Preteens, younger teens, and beginners should do fewer sets and repetitions than older teens and those who have been doing regular muscle fitness exercises. Check table 7.2 on page 81 and the information on page 82 of the middle school textbook and pages 218-226 of the high school textbook for more information on the number of sets and repetitions to perform.

What is the difference between aerobic activity and active aerobic activity?

Aerobic activity (as defined in your textbook) is any activity for which the body can supply enough oxygen to allow you to continue to be active for long periods. By this definition, walking, watching TV, playing computer games, and playing a musical instrument are aerobic activities because your body can supply enough oxygen to allow you to do them for a long time.

Active aerobic activity (as defined in your textbook) is an aerobic activity that is intense enough to elevate your heart rate into the aerobic target zone. Active aerobics are good for building cardiorespiratory fitness. Activities generally considered active aerobics can be done at a low intensity so that they fall below the aerobic target zone, in which case they would be aerobic but not active aerobics. For example, swimming slowly is an aerobic activity but is not an active aerobic activity. When swimming is performed vigorously enough to elevate the heart rate into the target zone, it is an active aerobic activity.

How do you measure your body fat?

Your body fat can be measured in a couple of ways. When you measure body fat you are trying to determine the amount of your body weight that is made up of fat (as opposed to other tissues such as muscle, bone, and body organs). The best methods are called laboratory measures and require experts who use expensive machines or equipment. DEXA is an X-ray technique that is considered the best way to measure body fat. It provides an X-ray picture that shows the bones and the fat and provides a measure of the percentage of the body tissue that is fat. Another very good laboratory measure is called underwater weighing. It uses the buoyancy of the body to calculate the percentage that is fat. For most people these are not practical because of the cost and time involved in having them done. Scientists have used these measures of body fat to create formulas that calculate estimates of body fat based on more practical methods.

More practical methods include skinfold measurements, body mass index, body measurements, and bioelectrical impedance. The following is an explanation of each of these.

Skinfold measurements use an inexpensive device called a skinfold caliper. The caliper is used to measure the thickness of folds of fat under the skin. A formula is then used to predict body fat from the skinfolds. To be accurate, the measurements must be made by a person who knows how to use the caliper and who has experience with testing. See page 95 in your text for more information.

Body mass index (BMI) estimates body fat based on the ratio of your height to your weight. To calculate your body mass index, first you measure your height and weight. Then you use a formula to calculate BMI using your height and weight. BMI does not determine body fatness, but it does give you a general indication about whether you are likely to be high in body fat. It has some limitations but is easy to measure. See pages 94 to 96 in your text for more information.

Body measurements of your waist size and hip size and other similar measurements can be used to estimate body fatness. You will learn more about these in high school. If you are interested in learning more, you can consult the high school version of the text Fitness for Life.

Bioelectrical impedance (BIA) machines have been shown to be accurate when used properly and when steps are taken to ensure that the machine is working properly. BIA uses a very, very low electrical current and measures how quickly it travels through your body. The current travels at different speeds in different types of body tissue. Calculations based on the speed of travel estimate the amount of body fat it traveled through. Like a scale for measuring weight, there may be some differences in measurement from machine to machine, so it is best to use the same machine each time you measure. Some schools and many doctors’ offices now have BIA for measuring body fatness.

For more information on body composition check Lesson 8.1 of the middle school textbook and Lesson 13.1 of the high school textbook.

When is the best time to do stretching exercises to improve flexibility?

The ability of your joints to move the way that they’re supposed to move is called flexibility. Long muscles and tendons allow you to have good flexibility. Stretching, using the types of static stretches and PNF stretches described in the text, is the best way to stretch muscles and tendons and improve flexibility.

The best time to do your stretching is when the muscles are warm. Many experts recommend that you do your stretching program after you have done a general warm-up or, even better, after you have been exercising for at least 10 minutes. Warm muscles stretch more easily than cold muscles, so your program will be more effective if you do your stretching after doing other exercise.

The warm-up before your exercise program is not the same thing as a stretching program or workout that you do as part of your total exercise program.

  • In a warm-up, you begin with a general total-body activity and then do a dynamic warm-up or stretching exercises.
  • As part of your total exercise program, you begin with exercise that gets your muscles warm, and you stretch afterward. For example, basketball players often do shooting drills, dribbling drills, and running drills before stretching.

Sometimes people do stretching exercises separately from other parts of their total exercise program. For example, they might stretch first thing in the morning or before going to bed at night. If you choose to do this, you should do a good general warm-up before stretching.

What do you call the ability to combine strength and speed?

Strength is the ability of the muscles to lift a heavy weight or exert a lot of force (page 9). Speed is the ability to get from one place to another in the shortest possible time (page 17). The combination of strength and speed is commonly referred to as power. Power, the ability to combine strength with speed while moving, allows you to do explosive movements such as jumping high, putting a shot, or swinging a softball or baseball bat to hit a ball a great distance (page 17). Strength is considered a health-related part of physical fitness, and speed is considered a skill-related part of physical fitness. Power is a combination of strength and speed, it is often considered a combined part of physical fitness, both health and skill related.

Why do you need physical activity?

There are many reasons we need physical activity, including these:

  • It is good for your health. Physical activity helps prevent health conditions such as heart disease, diabetes, and cancer. It helps build the bones and can help prevent back problems and injury.
  • It helps you look your best by building muscle and maintaining a healthy level of fat in the body.
  • It helps you enjoy life and have fun.
  • It can be a good way to meet other people and to work with others.

Why does the textbook sometimes use FITT and other times use FIT?

The acronym FITT is used to help you remember the formula for how much physical activity you need to perform to build fitness and health.

The F stands for frequency.

The I stands for intensity.

The first T stands for time.

The final T stands for type of activity or exercise.

Once you decide which type of activity you plan to do (such as moderate lifestyle activity, active aerobics, active sports and recreation, flexibility exercises, or muscle fitness exercises) you need only use FIT because the type of activity has already been determined (one of the five types listed in the previous sentence). FIT will help you determine the frequency, intensity, and time for the type of activity chosen.

How can I help my parents have better cardiorespiratory fitness?

Adults are often less active and less fit than teens. Adults are also nearly four times more likely to be overweight than teens. You can help your parents and other adults by discussing your concerns with them (that you know cardiorespiratory fitness is important for them too) and doing some of these things:

Ask the person (or people) to walk with you. A 30-minute walk is recommended for adults, but if the person is not often active, even a 10- or 15-minute walk is better than nothing. Try to find a regular time for a family walk.

Share information about good nutrition learned in this class and in this book. Let the person know that you are interested in eating healthy foods with him or her.

If the person smokes, encourage him or her to stop. Smoking hurts cardiorespiratory fitness and is a leading cause of heart disease. Smoking in the home exposes other family members to secondhand smoke and can harm them.

Research indicates that teens can influence their parents and other adults. When teens work together with adults, they are more active and eat better, which result in better fitness, lower body fat, and better health for all concerned.

If you want to play sports, is it better to specialize in one sport or learn to do several sports?

That's a very good question, but it's also a hard one to answer. A lot depends on your personal goals and personal abilities. Because we are most interested in the fitness, health, and wellness of teens, we encourage participation in a variety of activities from the Physical Activity Pyramid, not just one sport. Each of the five types of activities from the first three levels of the physical activity pyramid has different benefits, so performing a variety of activities will provide you with a variety of benefits in fitness, health, and wellness. Also, people who learn a variety of activities and perform them regularly as teens are more likely to be active and fit later in life. So if your goal is good fitness, health, and wellness both for now and later in life, we suggest learning many activities.

It is true, however, that many successful athletes specialize in one sport. They think that by specializing they can spend more time practicing to become really skilled at one thing rather than divide practice time among several sports. So it can be argued that if your goal is to be really good at one sport, specialization can work. The problem with that approach is that many young adults do not continue to play a sport after they get out of school. So people who learn only one sport may be better at it when they are young, but they may not be active later in life because they can do only one sport well.

Is it possible to be physically fit and still have too much body fat?

Yes, it is possible to have good physical fitness and still have too much body fat. But before we more fully answer the question, we want to say that it is best to be fit and to have a healthy level of body fat. As you learned earlier, there are many kinds of health-related physical fitness: body composition (also known as body fatness), cardiorespiratory fitness, flexibility, muscular endurance, and strength. All parts of fitness relate to each other, but each is also somewhat separate from all others.

So you can have good cardiorespiratory fitness and still have more body fat than you should have. Extra body fat will make it more difficult to score well on running tests of cardiorespiratory fitness because you have to carry more body weight during tests. You can be flexible and have a body fat level above the healthy fitness zone, but excess body fat can restrict range of motion in some joints. You can also be high in body fat and have good muscle fitness. Many sumo wrestlers are very overweight but can also be quite strong. Unfortunately, you can be quite strong (meaning you can lift a heavy weight) but have a hard time lifting your own body weight if you have excessive body fat.

Why do some kids who don't do a lot of exercise score better on fitness tests than some kids who exercise a lot?

It is true that sometimes people who do not do a lot of physical activity score better on fitness tests than others who are more active. That is more likely to be true when you are young than when you get older. The reasons some less active people can do well on fitness tests include heredity, maturation (age), and sex. Some people inherit physical characteristics from their parents that help them to do well on fitness tests. For example, there are various types of muscle fibers, and you may score well if you inherit the types of fibers that help you perform certain tests. The types of bones, joints, and body organs (such as the heart and lungs) that you inherit can affect your performance on fitness tests.

Also, some teens mature earlier than others. This means that they grow faster and their bodies produce hormones earlier than other teens do. People who mature early tend to do better on fitness tests than those who mature later. Teens in the same class who are older than others typically do better on fitness tests. As described in the book, males often do better than females in fitness activities that require muscle size.

As teens grow older, maturation and age become less of a factor because at some point all teens mature and get the fitness benefits of maturation. Also, heredity becomes less of a factor as you age. Among adults, healthy lifestyles are the main reason for good (or not so good) performance on fitness tests. For the reasons described here, we encourage you to focus on avoiding comparisons to others. Trying to reach the healthy fitness zone on all fitness tests is most important. We believe that self-comparisons over time are much more important than comparisons to other people.

In my school, we have 45 minutes of physical exercise per week. In your opinion, would an increase to 45 minutes per day in physical activity positively affect the students' ability to concentrate? Why or why not?

The authors do think that 45 minutes a day would positively affect students’ ability to concentrate and perform well on tests and in academic studies. The research supports my point of view. Taking 30 to 45 minutes a day for physical education is positively related to academic performance, and the time taken does not detract from performance. In addition, the time in physical education can enhance health and fitness and help students maintain a healthy body weight.

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