Chapter 5 Flashcards
Physiological Adaptations to Resistance Training
Increased: Strength, Power Output, Anaerobic Power, Vertical Jump, Speed, Fibre Size, ATP Stores, CP Stores, Glycogen Stores, Fat Free Mass
Decreased: Capillary density, mitochondria density, body fat
Central adaptations
The motor cortex activity will increase when force levels increase and also when we learn new movements.
Corticospinal Tract
Motor Unit adaptations
Max power and strength will increase in agonist muscles due to an increase in their recruitment, synchronization, and firing rate, or a combination of these.
During Resistance training, the muscle fibers become larger due to them being recruited based on their size. They are recruited consecutively in order. Advanced athletes may recruit in different orders due to adaptations.
The Size Principle
Lower threshold units first recruited, lower capacity to produce force than higher ones
Exception for explosive ballistic based contractions
Neuromuscular Junction
Increase Area
Synapses more dispersed and shaped more irregularly
End plate perimeter length/area increase
Acetylcholine receptors are dispersed greater
Neuromuscular Reflex Potentiation
Anaerobic training enhances this reflex. The magnitude and the rate of force development go up.
Anaerobic Training and Electromyography Studies
Increasing EMGs show greater neural activation.
Some studies have strength and power increases showing as much as 73%
Cross Education
Bilateral Deficits in untrained
An increase in the voluntary activation of the agonistic muscles occurs in Bilateral facilitation in trained or stronger people.
Muscle activity changes occur in the antagonist muscles during agonist movements.
Muscular Adaptations
The main adaptations that occur in skeletal muscle are: Increased size, fiber type transitions, enhanced biochemical components. These changes give us more strength, power and endurance.
Muscular Growth
Muscular hypertrophy is referring to enlargement of muscles due to increases in the cross-sectional areas.
Hyperplasia is an increase in muscle fiber numbers due to longitudinal splitting of the fibers.
Hypertrophy results from increases in myosin and actin in the myofibrils and increases in the myofibrils contained in muscle fibers.
Fiber Size Changes
Resistance training shows an increase occurs in both muscle fiber types.
Type I and II fiber area increases.
There are always greater increases with the Type II fibers.
Fiber Type Transitions
The continuum of fiber types is: I, Ic, IIc, IIac, IIa, IIax, IIx.
Structural and Architectural Changes
Myofibrillar volume, sarcoplasmic reticulum density, sodium potassium ATPase activity, T-tubule density, and Cytoplasmic density all increase with resistance training.
Calcium release is enhanced with sprint training.
The angle of pennation increases with resistance training.
Other Muscular Adaptations
Mitochondrial density decreases.
Muscle substrate content and enzyme activities change.
Capillary density decreases.
The buffering capacity increases.
Bone Modeling
This creates stimulus for the bone to form new bone where it is experiencing this deformation.
Osteoblasts lay down additional collagen.
The osteoblasts that were dormant move to this area that is being strained.
Bone diameter increases as the collagen fibers become mineralized.
General Bone Physiology
Trabecular bones respond much quicker to stimuli than cortical bones.
The minimal essential strain is the threshold stimulus used to initiate the formation of new bone.
MES is about one tenth of the force needed to fracture a bone.
If a force reaches this one tenth, or passes it, it will initiate new bone formation.
