CSCS key terms

A single alpha motor neuron and all the muscle fibers it activates. When the neuron fires, every fiber in that unit contracts. Small units control fine movements; large units generate high force.

The rule that motor units are recruited from smallest to largest as force demand increases. Small, slow units fire first, and large, fast units join in for high-force efforts.

The increase in muscle force produced by raising the firing frequency of motor units that are already active. Higher frequencies sum contractions and generate more tension.

A rapid eccentric stretch of a muscle followed immediately by a concentric action. Elastic energy and the stretch reflex increase force and power compared with a concentric action alone.

A sensory receptor inside skeletal muscle that detects how much and how fast the muscle is stretched. It triggers a reflexive contraction that resists the stretch and aids proprioception.

A sensory receptor at the junction of muscle and tendon that detects tension. When tension becomes excessive, it inhibits the muscle as a protective brake and provides proprioceptive feedback.

The exercise intensity at which blood lactate starts to rise faster than it can be cleared. It marks a growing reliance on anaerobic metabolism and is often stated as a percentage of VO2max.

The highest rate at which the body can take in, transport, and use oxygen during intense exercise. It is expressed per kilogram of body mass per minute and reflects aerobic power.

Excess post-exercise oxygen consumption: the oxygen uptake above resting levels after exercise ends. It supports phosphagen replenishment, lactate clearance, and restoration of temperature and hormones.

A short-term rise in muscle force and power after a heavy conditioning contraction. It is linked to greater motor unit recruitment and changes in myosin light-chain phosphorylation.

An increase in the cross-sectional area of muscle fibers caused by repeated training. It results from greater protein synthesis driven by mechanical tension and metabolic stress.

Any substance, device, or practice used to improve exercise performance or recovery. Examples include caffeine, creatine, and bicarbonate; some are banned in sport.

A ranking of carbohydrate foods by how quickly they raise blood glucose compared with a reference food. Low-index foods produce slower and flatter glucose responses.

A strategy that raises muscle glycogen by tapering training and eating a high-carbohydrate diet for several days before endurance competition. It can delay fatigue in long events.

A supplement that increases intramuscular phosphocreatine, helping repeated short, high-intensity efforts such as sprints and heavy sets. It is among the most researched ergogenic aids.

The difference between energy taken in from food and energy expended through metabolism, activity, and thermogenesis. Positive balance favors weight gain; negative balance favors weight loss.

Assisting a lifter during an exercise to prevent injury or help finish a repetition. It requires correct positioning, clear communication, and knowledge of the lift being performed.

A forced exhalation against a closed glottis that raises pressure inside the abdomen and chest. It stabilizes the spine during heavy lifts but temporarily raises blood pressure.

Simultaneous extension of the hips, knees, and ankles. This powerful action propels the body upward in jumping and weightlifting and is central to the clean and snatch.

The explosive phase of the Olympic lifts in which the bar accelerates upward as the hips, knees, and ankles extend. It follows the first pull and comes before the catch.

A training method that uses quick stretch-shortening cycles, such as jumps and bounds, to improve power. Movements are fast, with short ground contact times.

A plyometric drill in which the athlete steps off a box, lands, and immediately jumps again. Box height and contact time control the difficulty.

Specific Adaptation to Imposed Demands: the body adapts to the exact type of stress placed on it. Training should match the desired movement, intensity, and energy system.

The planned organization of training into phases that vary volume and intensity over time. It aims to peak performance at the right moment and reduce overtraining.

A training phase lasting several weeks to a few months that targets a specific goal, such as hypertrophy, strength, or power. It contains several microcycles.

The shortest planning phase in periodization, usually one week. It lays out daily sessions, exercises, sets, repetitions, and recovery within a mesocycle.

A measure of resistance training work calculated as sets multiplied by repetitions multiplied by load. It tracks training volume across sessions and phases.

Gradually increasing training demands through more load, more volume, or harder variations so the body keeps adapting. Without it, gains plateau.

A structured review of an athlete's sport, position, movement demands, injury history, and training status before a program is written. It identifies the qualities and muscles to train.

A guide linking repetition ranges to training goals. Low repetitions with heavy loads build strength, moderate repetitions build hypertrophy, and high repetitions build muscular endurance.

The extent to which a test measures the quality it is meant to measure. A valid test must also be reliable, but reliability alone does not make a test valid.

The consistency of a test's results when it is repeated on different occasions or by different people. High reliability means measurement error is small.

The degree to which a test score is free from scorer bias, so different evaluators reach similar results. It depends on clear criteria and standardized procedures.

An estimate of the typical error in a test score, given in the test's own units. It helps decide whether a change is real or within normal measurement noise.

The heaviest load a person can lift once with correct technique. It is the reference for setting resistance training loads as percentages of maximum.

The process of finding, judging, and reducing hazards that could cause injury or legal liability in a training setting. It includes policies, supervision, equipment checks, and emergency planning.

A written and rehearsed plan for responding to medical emergencies. It assigns staff roles, communication steps, equipment locations, and evacuation routes, and should be practiced regularly.

A process that tells participants the purpose, risks, benefits, and alternatives of a program or procedure, and records their voluntary agreement. It supports autonomy and limits liability.

A failure to use the care a reasonably prudent professional would use in similar circumstances, causing harm. A claim requires duty, breach, causation, and damages.

The level of care and skill a similarly qualified professional would provide in the same situation. It is the benchmark used to judge negligence claims.