health practices chapter 3

Skeletal Muscle

Makes up 40-45% of average adult's body weight, consists of long, narrow cylindrical cells with many striations and nuclei, and is voluntary.

Irritability

The ability of muscle to receive and respond to a stimulus.

Contractile Component

Protein structures in muscle that enable contraction.

Elasticity

The ability of a muscle to return to its resting length after being stretched.

Viscous

Resistance to elongation increases with the rate of stretch; protects against overstretching.

Hypertrophy

Increase in muscle cell diameter due to strength training with heavy weights and low repetitions.

Sliding Filament Theory

Describes muscle contraction through the binding and pulling of myosin and actin filaments.

Type 1 Muscle Fiber

Slow twitch, aerobic fibers suitable for prolonged, endurance activities, with slower contractions and higher fatigue resistance.

Type 2 Muscle Fiber

Fast twitch, anaerobic fibers capable of fastest contractions and greater force production, but fatigues quicker.

Agonist

A muscle whose contraction produces a desired joint movement.

Antagonist

A muscle with an opposite action to that of the prime mover; relaxes while the prime movers contract.

Synergist

A muscle that works with the agonist to help achieve the movement goal, neutralizing undesired secondary actions of the prime mover.

Stabilizer (Fixator)

A muscle that contracts isometrically to support or steady a body part against forces.

Stretch-Shortening Cycle

A quick pre-stretch of a muscle used eccentrically before a concentric contraction to produce greater force.