Section 13.1 The Importance of Physical Activity Objectives Explain some of the physical, psychological, and social benefits of physical activity. Define the five components of fitness. Describe five types of physical activity.

Myth Being thin is a sign of fitness. Fact Appearance is not a good indicator of overall fitness. Thin people who do not exercise are likely to have poor heart, lung, and muscular fitness. Identify another fitness misconception that teens may hold. Why do you think they have that misconception?

The Benefits of Physical Activity • Any movement that requires your large muscle groups to work is considered physical activity. Teens should spend 60 minutes or more each day performing some form of physical activity. The changes that occur due to physical activity are beneficial to your body, your mind, and your social interactions.

Physical Benefits Cardiovascular System Your heart and blood vessels receive the most benefits from regular physical activity. Weight Maintenance Staying at a healthy weight can reduce your risk for developing diseases such as diabetes, heart disease, and certain cancers. Bone Strength Your physical activities make your bones stronger and denser. Balance and Coordination Physical activity improves your balance and coordination, which may, in turn, improve your athletic ability.

Psychological Benefits During continuous exercise, your brain releases endorphins, chemicals that block pain messages from reaching your brain cells. People who exercise regularly are likely to be more self-confident and focused, and have reduced stress levels.

Social Benefits Exercise is also an opportunity to have fun. Physical activity can be a way to bond with family and friends or build new relationships.

The Components of Fitness • Physical fitness means that you have the energy and strength to participate in a variety of activities. There are five components of fitness: cardiorespiratory endurance muscular strength muscular endurance flexibility body composition

Cardiorespiratory Endurance Cardiorespiratory endurance means that your heart, blood vessels, and lungs are able to distribute nutrients and oxygen and remove wastes efficiently during prolonged exercise. As the heart muscles become stronger, more blood is pumped with each beat. The lungs become more efficient at delivering oxygen to the blood and removing carbon dioxide.

Muscular Strength The capacity of a muscle or a group of muscles to produce force is called muscular strength. The amount of weight you can lift is one measure of your muscular strength.

Muscular Endurance Muscular endurance is the ability of your muscles to work for an extended time. Developing muscular endurance requires repeated actions over an extended period of time.

Flexibility The ability to move a joint through its entire range of motion is called flexibility. This means that you can bend, stretch, and twist your body easily. Stretching exercises, if done correctly, can increase flexibility and may reduce the risk of injury during exercise.

Body Composition Body composition is the amount of fat tissue in your body compared to the amount of lean tissue, such as muscles and bones. Having too much, or too little, body fat can lead to health problems.

A Physical Activity Pyramid

Types of Physical Activity • Physical activities can be classified as aerobic exercise or anaerobic exercise. Strengthening and endurance activities can be further classified as isometric exercise, isotonic exercise, or isokinetic exercise.

Aerobic Exercise Ongoing physical activity that raises your breathing rate and heart rate is called aerobic exercise (ehr OH bik). Aerobic exercises increase the amount of oxygen that your body takes in and uses.

Anaerobic Exercise Intense physical activity that lasts for a few seconds to a few minutes is called anaerobic exercise. Most anaerobic exercises develop muscular strength, muscular endurance, or flexibility.

Isometric Exercise Isometric exercise (eye suh MET rik) is an exercise in which muscles contract but very little body movement takes place. If you do isometric exercises on a regular basis, the muscles you use will become stronger.

Isotonic Exercise Isotonic exercise (eye suh TAHN ik) involves contracting and relaxing your muscles through the full range of a joint’s motion. Through repetition of isotonic exercises, you can develop muscular strength and endurance.

Isokinetic Exercise In isokinetic exercise (eye soh ki NET ik) muscles contract at a constant rate. These exercises are often used as therapy to rebuild muscle strength after an injury.

Vocabulary physical activity Any movement that requires large muscle groups to work. endorphins Chemicals that block pain messages from reaching brain cells and produce feelings of pleasure. physical fitness Having the energy and strength to participate in a variety of activities. body composition A measure of how much body fat a person has, as compared to muscle and bone. aerobic exercise An ongoing physical activity that raises your breathing and heart rates.

Vocabulary anaerobic exercise Intense physical activity that lasts for a few seconds to a few minutes. isometric exercise Exercise in which muscles contract but very little body movement occurs. isotonic exercise Exercise that involves contracting and relaxing muscles through the full range of their joint’s motion. isokinetic exercise Exercise performed with machines that ensure muscles contract at a constant rate.