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About. Contractions, muscle disorders, and the effects of exercise. Types of contractions. Isometric contractions - muscle does not shorten & no movement occurs. Ex.- pushing against a wall Isotonic contractions - produces movement at a joint such as walking, running or breathing
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About Contractions, muscle disorders, and the effects of exercise
Types of contractions • Isometric contractions- muscle does not shorten & no movement occurs. Ex.- pushing against a wall • Isotonic contractions - produces movement at a joint such as walking, running or breathing • Twitch contractions- quick jerky contraction • Tetanic contractions – contractions which do not relax
Atrophy • Atrophy is when muscles shrink in mass from lack of use. • Why do you think this occurs?
It’s not a bad thing… • Muscular hypertrophy- increase in muscle size
MUSCULAR DISORDERS • Myo – prefix that means “muscle” • Myalgia – muscle pain • Myopathies – muscle disorders
MUSCULAR DISORDERS • 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
MUSCULAR DISORDERS • 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 20th century has nearly been eliminated by a comprehensive vaccination program.
MUSCULAR DISORDERS • Muscular Dystrophy • A genetic disease • Is actually a group of disorders characterized by muscle atrophy • Is often fatal
MUSCULAR DISORDERS • Multiple Sclerosis • An autoimmune disease characterized by chronic fatigue and weakness
Effects of exercise • Muscular hypertrophy- increase in muscle size • Improved tone and posture • More efficient heart and lung function • Decreased fatigue
Strength training • Increases the number of microfilaments in each fiber • Increases muscle mass
Endurance training • Increases the muscles’ ability to sustain moderate exercise over a long period • Also called “cardio” or “aerobic” exercise • 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.