SPMD 3410 CHAPTER 14: The Physiology of Strength Training

These flashcards cover the key concepts of exercise physiology related to resistance training, physiological adaptations, hormonal influences, and training principles from Chapter 14.

Muscular Fitness

A collective term used to describe muscular strength, endurance, and power.

Muscular Strength

The maximal force that a muscle group can generate, typically measured by the Gold Standard assessment known as the 1 Repetition Maximum ($1-RM$).

Muscular Endurance

The ability of a muscle to make repeated contractions against a submaximal load.

Muscular Power

The amount of work or force that is generated per unit of time.

Resistance Training (RT)

An anaerobic form of exercise used to improve muscular fitness.

High-resistance training

A training protocol involving $6-10$ reps to fatigue, resulting primarily in strength increases.

Low-resistance training

A training protocol involving $35-40$ reps to fatigue, resulting primarily in increases in endurance.

Isometric (Static) Exercise

An application of force without joint movement, such as a hand grip, plank, or wall sit.

Dynamic (Isotonic) Exercise

An application of force that includes variable resistance and joint movement.

Isokinetic Exercise

The exertion of force at a constant speed, often measured using an isokinetic dynamometer.

Progressive Overload

The periodic increase in resistance (weight lifted) to ensure continued overload of the muscle group for strength improvements.

Resistance Training Intensity

A consideration for training based on the percentage of $1-RM$ ($1$ Repetition Maximum).

Resistance Training Volume

The total amount of work performed, measured by the number of repetitions and sets.

Genetic Variation in Hypertrophy

Approximately $80\%$ of the differences in muscle mass between individuals is attributed to this factor.

High vs. Low Responders

A result of variations between individuals in their ability to activate recruitment of specific protein synthesis genes in response to resistance training.

Resistance Training Frequency

The general FIT principle suggesting $2-4$ days per week for full body or $4-6$ days per week for split routines.

Split Routine

A training schedule where the body is divided into different areas (e.g., upper vs. lower) with each trained in separate sessions.

Specific Rest Period for Muscle Recovery

A requirement of $24-48$ hours of rest between training sessions for the same muscle group.

Specificity of Speed ($V_{max}$)

The principle that the speed of muscle shortening during training should be similar to speeds used in competition.

Periodization

The systematic variation of volume and intensity over time to achieve optimal gains in strength, power, or hypertrophy.

Linear Periodization

A training shift from high volume/low intensity to low volume/high intensity over the course of a program.

Macrocycle

The largest phase of a periodization plan, typically representing a whole season or year.

Ultra Short-Term Performance (<10s)

High power events dependent on the recruitment of Type II muscle fibers and anaerobic energy sources like the ATP-PC system.

Neuromuscular Changes

The 'central' component of strength improvements, responsible for early gains within the first $8-12$ weeks of training.

Hypertrophy

The 'peripheral' component of strength improvements characterized by an increase in the cross-sectional area (CSA) of muscle fibers.

Type II Muscle Fiber Recruitment

A neural adaptation where the body gains a higher ability to selectively actuate higher-threshold motor units.

Motor Unit Synchronization

A major neural adaptation involving the organized timing of motor unit firing to increase force production.

Neural Inhibition Removal

A neural adaptation involving decreased activation of Golgi Tendon Organs ($GTOs$) to allow for greater force generation.

Hyperplasia

An increase in the total number of muscle fibers within a specific muscle; it plays a minor role ($5-10\%$) in human muscle enlargement.

Myofibrillar Proteins

Contractile proteins like actin and myosin that increase in size and number during hypertrophy.

Fast-to-Slow Fiber Shift

A resistance training-induced change where Type IIx fibers shift toward hybrid Type IIa fibers, typically after $8$ weeks.

Satellite Cells

Dormant cells located between the sarcolemma and basal lamina that facilitate growth, maintenance, and repair by providing new myonuclei.

Satellite Cell Activation

Stimulated by trauma or damage to the muscle fiber (such as Resistance Training), causing cells to proliferate and migrate to the site of damage.

Muscle Remodeling

The process of fiber disruption involving an increase in protein synthesis and a decrease in protein degradation.

Testosterone

The main anabolic steroid hormone that directly influences the nucleus to increase protein synthesis; levels increase acutely with heavy loads ($85-95\%$ of $1-RM$).

Growth Hormone (GH)

A polypeptide hormone that enhances amino acid uptake and supports hypertrophy of both Type I and Type II fibers.

Insulin-Like Growth Factor (IGF-1)

A polypeptide hormone secreted by the liver that initiates protein synthesis via the mTOR pathway, typically peaking $8-29$ hours post-exercise.

Cortisol

A catabolic glucocorticoid that promotes protein breakdown and inhibits protein synthesis, often increasing when muscle glycogen is low.

Overtraining Indicator

Chronic increases in cortisol levels combined with a decrease in performance.

Detraining Strength Loss

A slow decrease in strength (e.g., $31\%$ decrease over $30$ weeks) primarily due to neural adaptation changes in the CNS.

Retraining

The rapid regain of strength and muscle size, typically within $6$ weeks of resuming training.

Absolute Strength Difference

Untrained males are generally $50\%$ stronger in the upper body and $30\%$ stronger in the lower body than untrained females.

Relative Strength

Strength measured relative to the cross-sectional area (CSA) of muscle, which is similar between men and women ($3-4\,kg$ of force per $cm^2$).

Sarcopenia

The age-related loss of muscle mass, typically beginning after age $50$, involving the loss of both Type I and Type II fibers.

Concurrent Strength and Endurance Training (CET)

The combination of both training modalities which may impair strength gains compared to strength training alone.

AMPK Activation in CET

An endurance-induced signaling event that inhibits the mTOR pathway, thereby depressing protein synthesis.

mTOR (Mammalian Target of Rapamycin)

A major protein kinase and regulator of protein synthesis and muscle size, activated by phosphatidic acid ($PA$) and Rheb.

Mechanoreceptors

Sensors on the muscle membrane that detect muscle stretch and serve as the primary signal for resistance training adaptations.

Phosphatidic Acid (PA)

A lipid messenger synthesized in response to mechanoreceptor activation that helps activate the mTOR pathway.

Rheb (Ras Homolog Enrich in Brain)

A GTPase that, alongside Phosphatidic Acid, is necessary for the activation of mTOR.

Exercise Stress Adaptation

A process where muscle contraction activates primary and secondary messengers leading to gene expression and peak mRNA levels in $4-8$ hours.

Calcium (Secondary Messenger)

A primary signal for muscle adaptation that acts via calmodulin-dependent kinase.

Free Radicals

Unstable atoms or molecules produced during exercise that serve as primary signals for muscle adaptation.

Polypeptide Hormones

Hormones comprised of amino acids ($GH$, insulin, $IGF-1$) that bind to receptors on the sarcolemma rather than diffusing through it.

Steroid Hormones

Hormones comprised of lipids (testosterone, cortisol) that can diffuse directly through the sarcolemma into the nucleus.

Work:Rest Ratio

The duration of rest interval expressed in relation to the work interval; for example, a $1:1$ ratio.

Work Repetitions

The number of work intervals performed within a single set.

Novice Trainer Experience

Individuals with less than $1$ year of experience with resistance training.

Intermediate Trainer Experience

Individuals with $2-3$ years of experience with resistance training.

Advanced Trainer Experience

Individuals with greater than or equal to $3$ years of experience with resistance training.