the body. 38 terms, defined.
How the body produces and adapts to exercise: muscle actions and fiber types, energy systems, hormones and the mechanics of movement. Every definition is cited to a page in the textbooks and research coaches trust.
A
- Adenosine triphosphate (ATP)Adenosine triphosphate (ATP) is the molecule muscle cells break down to release energy for contraction.
- AgonistAgonist muscles, also called prime movers, are the muscles most directly responsible for producing a joint movement.
- AntagonistAntagonist muscles oppose the action of another muscle, such as the triceps opposing the biceps at the elbow.
B
C
- Cardiac outputCardiac output is the amount of blood the heart pumps per minute, equal to stroke volume times heart rate.
- Concentric muscle actionConcentric muscle action is muscle shortening under force as the muscle overcomes resistance, as in the lifting phase of a rep.
- CortisolCortisol is a stress hormone that promotes protein breakdown and helps maintain blood glucose during hard exercise.
D
E
- Eccentric muscle actionEccentric muscle action is a muscle lengthening while producing force because the resistance exceeds the force it produces.
- Exercise-induced muscle damage (EIMD)Exercise-induced muscle damage (EIMD) is disruption to muscle fibers and connective tissue after hard or unfamiliar exercise, especially eccentric work.
G
H
I
L
M
- Maximal strengthMaximal strength is the greatest external force a client can produce with an all-out effort against sufficient resistance.
- Mechanical tensionMechanical tension is force acting on muscle tissue during loading and is considered the main driver of muscle growth from training.
- Metabolic stressMetabolic stress is the buildup of metabolites such as lactate, inorganic phosphate and hydrogen ions during exercise.
- MitochondriaMitochondria are structures inside cells that use oxygen to produce most of the body's ATP, and aerobic training increases their number and size.
- Moment armMoment arm is the perpendicular distance from a force's line of action to a joint axis, which determines the torque that force produces.
- Motor unitMotor unit refers to one motor neuron and all the muscle fibers it controls.
- Muscle fiber typesMuscle fiber types are classes of skeletal muscle fiber, mainly slow-twitch Type I and fast-twitch Type IIa and IIx, with different speeds and fatigue rates.
- Muscle protein synthesis (MPS)Muscle protein synthesis (MPS) is the production of new muscle proteins, allowing muscle growth when it exceeds protein breakdown over time.
- Muscular powerMuscular power is force multiplied by movement velocity, as expressed in actions such as jumping, throwing and sprinting.
N
O
P
R
- Rate of force development (RFD)Rate of force development (RFD) is how quickly force increases, measured as the change in force divided by the change in time.
- Repeated bout effectRepeated bout effect describes the reduction in muscle damage and soreness when someone repeats an exercise they have done before.
S
- SarcopeniaSarcopenia is the age-related loss of muscle mass, accompanied by declines in strength, power and muscle quality.
- Stabilizer muscleStabilizer muscles hold a bone or joint steady so movement can occur elsewhere, often using an isometric contraction.
- Stroke volumeStroke volume is the amount of blood the heart ejects with each beat, measured in milliliters.
- SynergistSynergist muscles assist the agonist during movement by helping produce the movement or controlling unwanted motion.