Muscle Contractions & Basic Biomechanics – Vocabulary Flashcards (Lippert, Ch. 6–8)

Vocabulary-style flashcards covering key concepts from muscle contractions and basic biomechanics: contraction types, force–length/velocity relationships, tension components, force directions, planes, levers, and mechanical advantage.

Isometric contraction

A muscle contraction with no change in muscle length; tension is produced to stabilize a joint.

Concentric contraction

Muscle shortens as it generates force to move a limb against resistance.

Eccentric contraction

Muscle lengthens while generating force to control or resist movement.

Isokinetic contraction

Muscle contraction at a constant angular speed, typically using specialized equipment.

Length–Tension relationship

Maximal force at the resting length; force decreases when the muscle is too short or too stretched.

Force–Velocity relationship

Concentric: faster shortening reduces force; Eccentric: faster lengthening increases force.

Active tension

Force produced by cross-bridges within muscle fibers during contraction.

Passive tension

Force generated by elastic elements (tendons, connective tissue) when the muscle is stretched.

Internal force

Force generated by the muscle itself (intrinsic to the musculoskeletal system).

External force

Forces acting on the body from outside (e.g., gravity, external load).

Torque

Rotational effect of a force; Torque = Force × Moment Arm; varies with joint angle.

Sagittal plane

Plane that divides the body into left and right; flexion/extension occur here.

Frontal (coronal) plane

Plane that divides the body into front and back; abduction/adduction occur here.

Transverse (horizontal) plane

Plane that divides the body into upper and lower parts; rotation occurs here.

First-class lever

Lever with the axis between the force and resistance; e.g., head/neck.

Second-class lever

Lever with resistance between the axis and the force; e.g., tiptoes (heel raise).

Third-class lever

Lever with the force applied between the axis and resistance; most common; favors speed/ ROM (e.g., biceps curl).

Mechanical Advantage

Ratio of Force Arm to Resistance Arm; MA = Force Arm ÷ Resistance Arm; higher MA favors force, lower MA favors speed/mobility.