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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.