Resistance Training: Strength, Power, and Muscular Endurance

Comprehensive vocabulary flashcards covering the physiological mechanisms, neural and muscular adaptations, fatigue processes, and training prescription variables for strength, power, and muscular endurance.

Strength

The maximum force-generating capacity of a muscle or muscle group, typically measured through a one-repetition maximum ($1\text{RM}$).

Power

The rate of maximal force development, mathematically defined as force multiplied by velocity ($\text{Power} = \text{Force} \times \text{Velocity}$).

Motor Unit

The fundamental functional unit of the neuromuscular system, consisting of an alpha motor neuron and all the specific muscle fibers it innervates.

Fine Motor Units vs. Coarse Motor Units

Fine motor units consist of a single motor neuron controlling a small number of muscle fibers for precision tasks (e.g., fingers), whereas coarse motor units consist of a single motor neuron controlling a large number of muscle fibers for high force output (e.g., quadriceps).

Henneman's Size Principle

The neuromuscular recruitment hierarchy stating that motor units are recruited systematically from smallest to largest threshold, meaning low-threshold, slow-twitch motor units are recruited first, followed by larger, high-threshold, fast-twitch units as force demand increases.

Intramuscular Coordination

The neuromuscular capacity to voluntarily activate and recruit as many motor units within a single muscle as possible and discharge action potentials at high firing frequencies.

Intermuscular Coordination

The capacity of the nervous system to coordinate and synchronize all the distinct muscles of a kinetic chain involved in a multi-joint action.

Rate Coding

The modulation of muscular force generation achieved by increasing or decreasing the firing frequency (stimulation frequency) of active motor units.

Concentric Force-Velocity Relationship

The inverse biomechanical relationship during concentric actions in which muscle force output decreases progressively as the shortening velocity increases.

Physiological Cross-Sectional Area (PCSA)

The cross-sectional area of muscle perpendicular to the orientation of its fibers, which directly governs maximal isometric force production rather than the muscle's anatomical size.

Peak Power Output ($P_{\max}$)

The maximal power generated along the power-velocity continuum, which occurs at intermediate shortening velocities ($44\% V_{\max}$) against moderate or light loads (~$30\%\,1\text{RM}$ in general testing).

Strength Training Loading Prescription

A resistance protocol prescribing heavy loads of $85\text{--}100\%\,1\text{RM}$ for $\le 6$ repetitions (typically $1\text{--}6$ repetitions) across $2\text{--}6$ sets, utilizing rest intervals of $2\text{--}5\text{ minutes}$.

Power Training Loading Prescription

A resistance protocol prescribing non-maximal loads of $80\text{--}90\%\,1\text{RM}$ for $1\text{--}2$ repetitions (single-effort) or $75\text{--}85\%\,1\text{RM}$ for $3\text{--}5$ repetitions (multiple-effort) across $3\text{--}5$ sets to maximize explosive velocity.

3-1-1 Tempo

A movement cadence prescribed for maximal strength training consisting of a $3\text{-second}$ controlled eccentric lowering phase, a $1\text{-second}$ isometric pause, and a $1\text{-second}$ rapid concentric lift to maximize neural drive.

1-0-X Tempo

A movement cadence prescribed for power training featuring a controlled $1\text{-second}$ eccentric phase, no isometric pause ($0\text{ s}$), and an explosive concentric contraction ($\text{X}$) to maximize the rate of force development.

Phosphocreatine (PCr) Recovery Timeline

The time course of phosphagen recovery during inter-set rest intervals: approximately $50\%$ replenishment at $30\text{ s}$, $70\%$ at $1\text{ min}$, $85\text{--}90\%$ at $2\text{ min}$, $95\%$ at $3\text{ min}$, and $98\text{--}100\%$ at $5\text{ min}$.

Muscular Endurance

The physiological ability to sustain repeated muscular contractions or maintain submaximal force output over extended periods, typically encompassing efforts lasting longer than $90\text{ s}$.

Type I Muscle Fibers

Slow-twitch, fatigue-resistant skeletal muscle fibers possessing small motor neurons, high mitochondrial and capillary density, high oxidative enzyme capacity, low glycolytic capacity, and triacylglycerol as their primary storage fuel.

Type IIa Muscle Fibers

Fast-twitch, moderately fatigue-resistant muscle fibers with medium motor neurons, moderately fast contraction times, high mitochondrial density, and intermediate-to-high oxidative and glycolytic capacities.

Type IIx Muscle Fibers

Fast-twitch, highly fatiguable fibers characterized by large motor neurons, rapid contraction times, low capillary and mitochondrial densities, high glycolytic capacity, and creatine phosphate and glycogen fuel stores.

Mitochondrial Biogenesis

The cellular process of synthesizing new mitochondria and increasing mitochondrial density and oxidative enzyme content, mediated by signaling proteins such as PGC1-alpha in response to endurance stimuli.

Fatigue (Resistance Training)

An exercise-induced decline in maximal force- or power-generating capacity that begins early in an exercise bout and develops progressively well before full voluntary failure.

Crossbridge (XB) Determinants of Muscular Force

the total number of cycling crossbridges, the individual force generated per crossbridge, and the rate of crossbridge cycling.

Excitation-Contraction Coupling (ECC) Failure

A peripheral mechanism of fatigue where action potential transmission down the transverse tubules fails to trigger sufficient $\text{Ca}^{2+}$ release from the sarcoplasmic reticulum lateral sacs, thereby reducing crossbridge cycling.

Motor Unit Rotation

A neuromuscular coping mechanism observed during prolonged submaximal or postural muscle actions wherein fatigued motor units deactivate while alternate inactive units are recruited to sustain total required force.

Muscular Endurance Prescription

A resistance protocol designed to tax oxidative pathways and delay fatigue, prescribing loads $\le 67\%\,1\text{RM}$ (or $50\text{--}75\%\,1\text{RM}$), $\ge 12$ repetitions (up to $30$), $2\text{--}3$ sets, and short rest intervals of $\le 30\text{ s}$.