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Ask students to define muscle or the muscular system. If students are having trouble defining the terms, ask students to describe the function of a muscle. What does a muscle help us do? The muscular system includes all of the muscles in the body and muscles are bundles of cells and fibers that work by tightening up (contracting) and relaxing. Explain to the students that there are over 600 muscles in the body. Muscles function to move the body. There are three main types of muscles; Smooth Muscles, Cardiac Muscles, and Skeletal Muscles.
Smooth Muscles are involuntary muscles that work all the time without intentional thought or without a choice. Smooth muscles are found in the stomach, bladder, and eyes. Explain to students that muscles in the stomach help to digest food after it has been swallowed. Also, when someone is feeling sick, these same muscles aid in throwing up. In the bladder, muscles relax to hold in urine and contract to push the urine out. Blinking muscles in the eye help to protect the eye, keep the eye moisturized, and clear pollutants from the eye.
The cardiac muscle also known as the heart is an involuntary muscle. The heart contracts as blood is pumped through the circulatory system and relaxes to allow blood back to the heart.
Skeletal muscles are voluntary muscles. These muscles carry out pre-conceived or intentional actions. For instance, in order to move a hand, the brain processes the thoughts about moving the hand and sends signals to the hand to move. The hand in return moves. This is accomplished by tendons that attach the muscle to the bone. This muscle, bone and tendon group pulls to cause movement. In fact, muscles usually work in pairs to pull and relax. For instance, to bend the arm, the bicep muscle pulls and the tricep muscle relaxes. In contrast, extending the arm or making it straight requires the tricep muscle to pull and the bicep muscle to relax. Some examples of skeletal muscles include pecs, deltoids, and quadriceps.
Brainstorm with students the meaning of flexible and the purpose of stretching. Explain that flexible means capable of being bent or twisted without being injured. Explain to students muscles must move to remain healthy and functional. When muscles are not used, they lose their ability to contract and perform as they were intended. They may become weak or they may become tight, and when eventually used, be painful. Stretching is significant because it provides a workout for your muscles and enables muscles to become flexible when doing physical activity.
Ask students when they should stretch. Stretching should be done before and after exercise also explain that it is good to stretch at any time of the day. Stretching can be done in the morning when you wake up, while you watch TV, during breaks at school or any other time. The more you stretch, the more flexible you will become.
Explain that students should stretch before doing a high-energy activity. High-energy activities work your muscles, and your muscles are more likely to get strained or injured when they are working hard. Stretching makes it easier for a person to bend and flex the body without sustaining an injury.
Review the benefits of stretching:
To cultivate interest in stretching, flexibility and muscle types, students will participate in a stretching routine and a scavenger hunt. Emphasize that stretching can be accomplished at anytime but it is important to stretch before and after physical activity and exercising.