Resistance Training Adaptations Quiz

Neuromuscular Adaptations

• Resistance training (3-6 months) improves force production and maximal movement.
• Strength gains range from 25% to 100%.
• Neural control and muscle hypertrophy are altered.
• Strength gains are greater in young males.
• Muscle plasticity is a high factor.

Responses to Training Stress

• Selye's General Adaptation Syndrome (GAS) is important.
• The GAS model has Alarm, Resistance, and Adaptation/Exhaustion stages.
• Training stress is a key consideration.
• Proper training can lead to adaptations, while improper training may lead to exhaustion.

General Adaptation Syndrome

• The Alarm phase is the initial phase of training, characterized by decreased performance due to fatigue, when the stimulus is first recognized.
• The Resistance phase is the second phase where the body adapts and the system is returned to baseline or exceeds it.
• The Supercompensation phase is the new level of performance capacity that occurs after the adaptive response in the resistance phase.
• The Overtraining phase results from excessive stress, suppressing performance and, potentially, resulting in overtraining syndrome.

Muscle Damage Elicits Adaptations

• Muscle damage from unaccustomed eccentric exercise (downhill running, slowly lowering weights) leads to high muscle force damage causing sarcolemma release of cytosolic enzymes and myoglobin.
• Damage to contractile myofibrils and non contractile structures from metabolites such as calcium accumulation leads to reduced force capacity.
• The inflammation process begins, leading to muscle repair and increased resistance to future exercise damage.

Example of Glycogen Supercompensation

• Glycogen levels decrease during exercise and recover to higher levels during recovery.
• Sufficient carbohydrate intake during recovery is important for enhanced glycogen storage, leading to superior performance.

Adaptations to Resistance Training

• Numerous physiological adaptations occur in response to resistance training, affecting various systemic variables.
• These adaptations include changes in muscle fiber size, number, type, strength, mitochondria volume and density, twitch contraction time, enzyme activity, glycolytic enzymes, carbohydrate, basal metabolism and intramuscular fuel stores.
• Resistance training triggers increases in aerobic capacity, ligament strength, and body composition (fat loss & muscle gain.)

Adaptations in all elements of Force Gradation

• Force generated in a single muscle fiber depends on the number of crossbridges.
• 5 factors (recruitment number, discharge frequency, type of motor unit, reflex activation, and contraction speed) acutely increase force generation.
• Neuromuscular adaptations modify these factors leading to increased force output.

Neural Adaptations

• Anaerobic training affects the neuromuscular chain from higher brain centers to individual muscle fibers.
• High-intensity training leads to greater neural adaptations early in the program.
• Central adaptations involve increased motor cortex activity during new exercises or movements with increased force.
• Motor unit adaptations (recruitment, firing rate, synchronization, etc.) lead to strength and power gains in agonist muscles.
• Untrained individuals typically have 70% of muscle tissue activation capacity.

Neuromuscular Junction

• Anaerobic training affects the Neuromuscular Junction size and shape increasing surface area.
• More dispersed and irregularly shaped synapses, and increased total length of nerve terminals occur.
• Increased end-plate perimeter length, area, and dispersion of acetylcholine receptors within the end-plate region.

Proprioceptor Adaptations

• Anaerobic training may enhance the stretch reflex response and improve the magnitude and rate of force development.
• Muscle spindles and elasticity properties improve, leading to shortened amortization phase.
• An increase occurs in the Golgi tendon organ (GTO) threshold.
• Inhibitory impulses are reduced.

Size Principle Adaptations

• Heavy resistance training increases the size of all muscle fibers (Type I & II), recruiting them in consecutive order based on the size principle.
• Experienced lifters may exhibit selective recruitment, prioritizing larger motor units for power and speed movements.

Muscular Adaptations

• Anaerobic training leads to muscle hypertrophy and an increase in strength and power.
• Connective tissues like tendons and fascia also strengthen.
• Metabolic changes include changes in muscle substrate content and glycolytic enzyme activity.
• A potential decrease occurs in mitochondrial and capillary density while buffering capacity is enhanced.
• Fiber type changes might be observed.

Muscular Adaptations Terms

• Hypertrophy involves an increase in the cross-sectional area/diameter of existing muscle fibers.
• Hyperplasia involves an increase in the number of muscle fibers (splitting).
• Atropy refers to a decrease in muscle girth.
• Sarcopenia is age-related muscle atrophy

Muscular Hypertrophy

• Hypertrophy can occur in two forms: Sarcoplasmic, and Myofibrillar.
• Sarcoplasmic hypertrophy involves an increase in the amount of sarcoplasm.
• Myofibrillar hypertrophy refers to an increase in myofibril size and number of myofilaments.
• This leads to increased muscle strength due to more sarcomeres in parallel.

Key Point

• Hypertrophy involves increased synthesis of contractile proteins such as actin, myosin.
• New myofilaments are incorporated into existing myofibrils, increasing the fiber diameter.

Satellite Cells & Hypertrophy

• Satellite cells are myogenic stem cells essential for muscle regeneration and hypertrophy.
• Acute muscle damage or rapid stretching stimulates satellite cell activation and proliferation.
• Migrating satellite cells repair injured muscle fibers by becoming myonuclei.
• Maintaining adequate myonuclear domain is crucial for muscle hypertrophy.

Muscular Adaptations

• Resistance training alters muscle structure and architecture by increasing myofibrillar volume, sarcoplasmic density, sarcoplasmic reticulum T-tubule density, and sodium-potassium ATPase activity.
• Sprint training enhances calcium release.
• Other muscular adaptations may include changes in reduced mitochondrial density, capillary density decreased, and acid-base balance.

Connective Tissue Adaptations

• Tendons, ligaments, and fascia grow primarily due to mechanical stresses during exercise.
• Anaerobic exercise exceeding a strain threshold alters connective tissue.
• Fibroblasts create collagen fibers, crucial structural components for connective tissues (bone, tendons, ligaments).
• Collagen fibers have a similar arrangement as muscle fibers.

Connective tissue adaptations specificity

• Collagen fibril diameter increases, increasing strength.
• Number of collagen fibers and packing density increase.
• Connective tissues further strengthen where they join bones and in fascia throughout skeletal muscle.

General Bone Physiology

• Trabecular (spongy) bone reacts faster than cortical (compact) bone to stimuli.
• The Minimal Essential Strain (MES), needed for new bone formation, is approximately 1/10th of the force needed to fracture bone.
• Muscle strength and hypertrophy relate to increased bone force exertion, leading to bone mineral density.

Bone Remodeling

• Bone bending from stress causes osteoblasts to proliferate, lay new collagen fibers within the periosteum, and lead to the growth of bone in that area.
• Previously dormant osteoblasts migrate to the stressed regions.
• Existing collagen fibers are mineralized, effectively increasing bone size.

Why do we see specific Adaptations?

• Specific stressors (e.g., high load vs. high volume) lead to specific adaptations.
• These adaptations differ based on the type of training stress (load or volume, high volume/short rest vs. strength/hypertrophy).

Training Type → Adaptations

• General adaptation syndrome principle shows that the type of stressor directly links to the type of adaptation.
• High load resistance training prioritizes strength adaptations (high load, low reps, long rest)
• High volume / short rest prioritize hypertrophy adaptations (high volume, low load, short rest).

Review Questions

• General adaptation syndrome, the importance of progressive overload.
• Neural adaptations in strength increases (motor cortex, motor units, neuromuscular junctions, recruitment, and firing)
• Reps and load relate to strength or hypertrophy (high reps vs. low reps)
• Neural Adaptations: central nervous system, motor units, neuromuscular junctions, and proprioceptors.
• Muscular adaptations to anaerobic training.
• Reasons for muscle fiber hypertrophy mechanisms.

Test your knowledge on the physiological responses and adaptations that occur during resistance training. This quiz covers topics such as the role of osteoblasts, neural adaptations, and the impact of mechanical strain on muscle development. Understand the principles behind strength training and its effects on the body.