PE - 1.2.4 - A healthy active lifestyle and your muscular system

Role of muscular system:

• muscles move by contracting and lengthening (relaxing)
• muscles define body shape and maintain posture
• work either voluntarily through planned contractions
• or involuntarily where muscles contract and lengthen by themselves (internal organs)
• voluntary muscles cause movement which people conciously control
• can be trained to be stronger and work for long periods of time without getting tired
• muscular endurance - light weights, lots of reps
• muscular strength - heavy weights, few reps

Movements of the body

Adduction:

• adding to the body
• bringing part of the body towards center

Abduction:

• opposite to adduction
• movement away from the center

Flexion:

• decreasing the angle between a joint

Extension:

• opposite to flexion
• increasing the angle between the joint

Rotation:

• angle of joint doesn't change
• moves in a circular motion

Muscles of the body

• muscles attached to bones by tendons
• muscles can only contract to produce movement by pulling the bone
• a second muscle is needed to pull the bone the other way
• muscles arranged in antagonistic pairs
• one muscle contracts, other relaxes to produce movement
• e.g. biceps and triceps - elbow flexes and extends
• hamstrings and quadriceps - flexion and extension at knee

• Deltoid - abducts arm at shoulder - serve in tennis
• trapezius - rotates the shoulder blades backwards - rowing
• lattisimus dorsi - rotates upper arm at shoulder - swimming butterfly
• pectoral - adduction of the arm - swimming front crawl
• abdominals - flexion and rotation of hip - heading a football
• biceps - flexion at elbow - bending the arm to throw a cricket ball
• triceps…