National 4 Science

1. National 4 Science Human Health Muscles and a Healthy Body

2. Muscles Learning Intentions: • Why do we need muscles? • Why do muscles need to be exercised? • How do muscles work to produce movement? • Name a low tech method of measuring muscle strength • Name a high tech method of measuring muscle strength • What is muscle fatigue?

3. Why do we need muscles? • We need muscles to produce movement

4. Why do muscles need to be exercised? • Muscles need to be exercised to improve their: Strength Size Blood supply

5. How do muscles produce movement? When bicep contracts the tricep relaxes in order to raise the lower arm When the tricep contracts the bicep relaxes to straighten the lower arm

6. Measuring muscle strength • Low tech method of measuring muscle strength: • bathroom scales • High tech method of measuring muscle strength: • Grip strength dynamometer

7. Measuring your grip strength • Squeeze scale with left hand • Take reading • Repeat three times • Calculate average • Repeat with right hand • Are the readings the same? • If not why not? • Squeeze dynamometer with left hand • Take reading • Repeat three times • Calculate average • Repeat with right hand • Are the readings the same? • If not why not?

8. Muscle fatigue • Copy and complete the following passage using the word below Oxygen (x2) recovery time increases lactic acid (x2) Muscles require oxygen to work efficiently. When exercising breathing rate __________ to supply our muscle cells with ___________, to make energy needed for movement. Muscle fatigue occurs during exercise when insufficient ___________ is available and ________ ______ is produced. Muscle fatigue is relieved by a period of rest. During this time the _____ _____ is broken down. The period of rest is called the __________ _____.