Kinematics, Kinetics, and Bioenergetics Vocabulary

Comprehensive vocabulary flashcards covering biomechanical principles (kinematics, kinetics, internal forces) and bioenergetics concepts (energy systems, rate-limiting enzymes, metabolism).

Kinematics

A branch of science that deals with the motion of a body, irrespective of the forces required to cause that motion.

Kinetics

A branch of science that deals with the effects of forces upon the motions of material bodies.

Scalar

A single or discrete number that describes a phenomenon, such as average speed or range of motion.

Vector

Continuous or time-series numbers that describe a phenomenon, such as frame-by-frame velocity or angular acceleration.

Sagittal Plane

A motion plane dividing the body into right and left halves, associated with flexion and extension around a coronal (medial-lateral) axis.

Frontal Plane

A motion plane dividing the body into anterior and posterior halves, associated with abduction and adduction around an antero-posterior axis.

Transverse Plane

A motion plane dividing the body into superior and inferior halves, associated with internal and external rotation around a vertical axis.

Velocity

A kinematic variable describing the speed and direction of motion, or the rate of change in position, measured in $m/s$ or $^\circ/s$.

Acceleration

A kinematic variable describing the rate of change in velocity ($A = \frac{V}{\text{time}}$), measured in $m/s^2$ or $^\circ/s^2$.

Arthrokinematics

The surface kinematics occurring at joint articular interfaces, consisting of roll, slide, and spin motions.

Convex-Concave Rule

An arthrokinematic rule stating that when a convex articular surface moves on a stationary concave surface, roll and slide occur in opposite directions.

Concave-Convex Rule

An arthrokinematic rule stating that when a concave articular surface moves on a stationary convex surface, roll and slide occur in the same direction.

Newton's First Law of Motion

The Law of Inertia, stating that an object will remain at rest or in motion at a constant velocity unless an outside force acts upon it ($\Sigma F = 0$).

Newton's Second Law of Motion

The Law of Acceleration, stating that the acceleration of an object is directly proportional to the net force applied and inversely proportional to its mass ($F = ma$ or $a = \frac{F}{m}$).

Newton's Third Law of Motion

The Law of Reciprocity, stating that for every action force, there is an equal and opposite reaction force ($F_{\text{action}} = F_{\text{reaction}}$).

Torque

A rotational force produced around an axis, calculated as the product of force and its moment arm ($T = F \times r$).

Stiffness

The linear resistance of a material or body to deformation, defined mathematically as $K = \frac{\Delta F}{\Delta L}$.

Quasi-Stiffness

The non-linear resistance of a joint to rotational deformation during movement, defined as $K = \frac{\Delta F}{\Delta L}$.

Stress

The internal resistance of a material to an external force, defined as force divided by area ($\frac{F}{A}$).

Strain

The relative change in length of a material resulting from applied force ($L_2 - L_1$).

Frictional Force

The resistive force acting opposite to the direction of motion or attempted motion between two contacting surfaces ($f = \mu_k N$).

Fick's Law of Diffusion

A principle stating that the rate at which particles move is directed from regions of high concentration to regions of low concentration.

First Law of Thermodynamics

A fundamental law stating that energy cannot be created or destroyed, only transferred or transformed.

Homeostasis

The dynamic maintenance of a stable internal environment during a resting, low-energy state.

Steady State

Physiological constancy maintained through elevated effort, achieving a balance between supply and demand during exercise or high-energy states.

Negative Feedback Loop

A physiological control process that produces an opposing reaction to a disruption from a set target value.

Bioenergetics

The flow of energy through metabolic pathways and the study of how chemical energy is harnessed to produce work via muscle action.

Exergonic Reaction

A chemical reaction that releases free energy as reactants are converted into products.

Endergonic Reaction

A chemical reaction that requires energy input to proceed from reactants to products.

Phosphagen System

An anaerobic energy system using stored phosphocreatine (PCr) to rapidly generate ATP for high-intensity efforts lasting approximately $0 - 15\,s$.

Creatine Kinase

The rate-limiting enzyme of the phosphagen system that catalyzes the breakdown of phosphocreatine to rephosphorylate ADP into ATP.

Phosphofructokinase

The rate-limiting enzyme of glycolysis that controls the pathway's rate of ATP production.

Isocitrate Dehydrogenase

The rate-limiting enzyme responsible for regulating energy yield in the Krebs cycle.

Anaerobic Glycolysis

The cytosolic breakdown of glucose or glycogen without oxygen, providing rapid ATP production for high-intensity efforts lasting up to $\sim 2\,min$.

Lactate

A compound formed when pyruvate buffers hydrogen ions ($H^+$), which regenerates $NAD^+$ to keep glycolysis functioning.

Beta Oxidation

The mitochondrial pathway that breaks down triglycerides into Acetyl-CoA to produce large amounts of ATP without requiring $NAD^+$ buffering.