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.