Chapter 11 Definitions

agonist: the muscle causing a movement

all-or-none law: the fact that when a muscle fiber (or motor unit) responds to a single impulse at or above threshold value by contracting, the tension produced is independent of the intensity of the stimulus

antagonist: the muscle whose contraction opposes a movement

bilateral deficit: a decrease in the strength of a muscle group when the contralateral limb is concurrently performing a maximal contraction

concentric: muscle action that involves the production of force while the muscle is shortening

conductivity: the ability of muscle tissue to propagate a stimulus throughout any one fiber in skeletal muscle and from fiber to fiber in smooth and cardiac muscles

contractility: the ability of muscle tissue to contract

contraction phase: the period of muscle twitch during which the muscle shortens (also called shortening period)

cross-education effect: the phenomenon of strength increases in a contralateral (opposite) limb as a result of unilateral training; also known as the cross-training effect

delayed onset muscle soreness (DOMS): the pain caused by microtrauma of the muscle felt 24 to 48 hours after an exercise bout

dynamic constant external resistance (DCER) muscle action: a type of muscle action in which the external resistance remains constant throughout the movement; also known as isotonic muscle action

eccentric: a muscle action that involves the production of force while the muscle is lengthening

hyperplasia: an increase in the number of elements comprising a part (such as tissue cells)

hypertrophy: an increase in the size of existing parts (such as the size of the cells of a tissue)

irritability: muscle tissue’s responsiveness to stimuli

isokinetic: muscle action that has a constant velocity of movement

isometric: muscle action involving tension production without movement at the joint or shortening of the muscle fibers; also known as static muscle action

isotonic: muscle action in which the external resistance remains constant throughout the movement, also known as dynamic constant external resistance (DCER)

latent period: the short delay between the application of a stimulus and the beginning of muscular contraction

muscle atrophy: shrinking of a muscle

overload: a basic principle of resistance training, that in order to promote strength gains and hypertrophy, a resistance training program must demand more of a muscle or muscle group than it normally performs

overtraining: the adverse effects on health and performance that often result from increasing the total volume of training too quickly

periodization: periodic changes in a resistance training program to minimize boredom and facilitate adherence; a basic principle of resistance training

plyometrics: a type of training involving the stretching of a muscle through an eccentric (lengthening) phase followed by a forceful concentric (shortening) muscle action

progression: a basic principle of resistance training, that in order to maintain overload and continue to see adaptation from a resistance training program, it is necessary periodically to increase the volume of training

rate coding: the process of changing the firing frequency of motor units to produce varying amounts of tension in a muscle

recruitment: the calling into play of additional numbers, as in the additional motor units called into play in order to increase the tension production in a muscle

relaxation period: the lengthening period that follows the contraction phase of a muscle twitch

repetition maximum (RM) load: the maximum amount of weight that can be lifted for a specific number of repetitions

shortening period: the phase of muscle twitch in which the muscle shortens (also called contraction phase)

size principle: the fact that the small motor neurons innervating slow twitch, oxidative fibers have the lowest threshold for activation and are therefore activated first during the recruitment of motor units for muscular contraction

specificity: a basic principle of resistance training that suggests that the adaptations that occur as a result of a resistance training program will be specific to the characteristics of the program

summation of twitches: the increase in tension produced in a muscle as a result of stimulation before the muscle is allowed to relax

tetanus: a sustained muscular contraction caused by a series of stimuli so frequent that the individual muscular responses are fused

torque: rotary force production

unilateral imagined training: training that involves thinking about, but not actually performing, a resistance exercise with only one limb