1. About Contractions, muscle disorders, and the effects of exercise

2. Types of contractions w Isometric contractions- muscle does not shorten & no movement occurs. Ex.- pushing against a wall w Isotonic contractions - produces movement at a joint such as walking, running or breathing w Twitch contractions- quick jerky contraction w Tetanic contractions – contractions which do not relax

3. Atrophy w Atrophy is when muscles shrink in mass from lack of use. w Why do you think this occurs?

4. It’s not a bad thing… w Muscular hypertrophy- increase in muscle size

5. MUSCULAR DISORDERS w Myo – prefix that means “muscle” w Myalgia – muscle pain w Myopathies – muscle disorders

6. MUSCULAR DISORDERS w Injury Strain – tearing or stretching fibers, caused by overexertion or trauma A strain near a joint can be a SPRAIN Inflammation – myositis Crush injuries can release muscle contents and cause kidney failure Stress can cause neck and back pain

7. MUSCULAR DISORDERS w Infections Poliomyelitis was an infection of muscles that caused paralysis and often death. The president Franklin Delano Roosevelt had polio and spent most of his adult life in a wheelchair. “Polio” was common in the early 20 th century has nearly been eliminated by a comprehensive vaccination program.

8. MUSCULAR DISORDERS w Muscular Dystrophy A genetic disease Is actually a group of disorders characterized by muscle atrophy Is often fatal

9. MUSCULAR DISORDERS w Multiple Sclerosis An autoimmune disease characterized by chronic fatigue and weakness

10. Effects of exercise w Muscular hypertrophy- increase in muscle size w Improved tone and posture w More efficient heart and lung function w Decreased fatigue

11. Strength training w Increases the number of microfilaments in each fiber w Increases muscle mass

12. Endurance training w Increases the muscles’ ability to sustain moderate exercise over a long period w Also called “cardio” or “aerobic” exercise w Does not usually result in hypertrophy More blood vessels develop to meet the need of the muscles. This increases efficiency of delivery of oxygen and nutrients to muscles.