Training adaptations Flashcards
What 3 ways can skeletal muscle performance be improved
Increasing its size
Fibre type transition
Enhanced Biochemical & ultra structure components
What is hypertrophy?
increased muscle cross sectional area
more common in response to resistance training
What is hyperplasia?
increase in number of muscle fibres (longitudinal fibre splitting)
How does hypertrophy work
occurs in parallel, widening muscle but some exercises can stimulate lengthening hypertrophy
What effect does having more sarcomeres in series give?
Higher velocity of contraction & greater shortening capacity
How is type 1 & 2 muscle fibre hypertrophy different?
Type 2 - increasing synthesis
Type 1 - decreasing degradation
How does hypertrophy occur?
muscle damage
Satellite cells activate and migrate to site
they proliferate
become myotubes
What is mechanical tension and how does it cause hypertrophy
The ability to sense the muscle is undergoing a stretch
integrins are activating stimulating hypertrophy
How does metabolic stress cause hypertrophy
Lactate build-up, H+ ions, muscle ischemia, glycolysis, free radical production
all lead to ^ fibre recruitment, ^ hormones, cellular swelling,
How does muscle damage cause hypertrophy?
damage to myofibrils, sarcolemma = ^ IGF etc which increase satellite cell proliferation
What is myogenesis?
the replacement of old/damaged muscle fibres
how does Fibre type transition occur
type 2b move to type 2a
allows for more force to be produced over time
What does resistance training do to pennation angle?
2-5 degree increase due to CSA increase
Cortical or Subcortical changes from resistance training?
study that increased finger strength via training showed corticospinal input of given magnitude was activating fewer motor neurons
Does strength training speed up neural drive?
Some studies show no evidence some show some, is dependant on how and where the data is measured
Neuromuscular junction strength training test in rats - results
Increased area of neuromuscular junction
more dispersed synapses
increased end-plate perimeter & greater dispersion of ACh receptors
Muscle spindle adaptations to training
enhance the stretch reflex response (20-50%)
Enhances the magnitude of force and rate of force development
How does power training effect EMG
can increase activity by up to 75%
could be from motor unit firing frequency, recruitment or synchronisation
Rate of force development
Studies show an increase in rate of force production following a heavy resistance training program
Why do we see an increase in rate of force development
faster depolarisation of sarcolemma
quicker fibre recruitment
increased firing frequency
enhanced muscle spindle activation
How are the best neural adaptations achieved?
High loads
fast velocity
explosive movements
Cross education of neural adaption theory explained
study shows 32% increase in strength in trained limb but also 10% in untrained limb
untrained limb can access the adapted control system
spill over of neutral drive stimulation that causes adaptions in untrained limb
What is Post activation potentiation (PAP)
An increase in muscle twitch after a conditioning contractile activity
eg 90% 1RM 1-5 sets before competition can give 1-10% perf increase
What is the mechanism behind PAP
quicker recruitment of type II fibres
increased & more synchronised motor neuron pool excitability
^ ACh release
More ATP broken down
How is PAP balanced with fatigue to maximise performance
don’t use a conditioning stimulus that causes too much fatigue
optimal to give 7-10 min recovery
How can bone strength be increased via training?
^ deposition of mineral salts
^ production of collagen fibres
Trabecular bones respond quicker
Factors for bone remodelling
Weight bearing
Magnitude, rate & volume of load
Direction of force
Pull of the tendon on bones
What is wolfs law?
A bone grows/remodels in response to the forces or demands placed upon it
What forces in bone bring about change
Tension - pulling (narrowing/lengthening)
Compression - (shortening/widening)
Shear & torsion - (angular distortion)
Overall = bending
Stress definition
level of force encounter by tissue
Strain definition
magnitude of deformation in proportion to stress applied
What is the minimal essential strain?
Around 10% of what is required for a fracture
What is mechanotransduction?
Bone fluid flows through canals in bone - is sensed by osteocytes promoting remodelling
Training guidelines to bring about bone adpatations
High load, low volume
High velocity, long rest
What is a collagen?
a triple helical protein, with multiple subtypes that upon:
- Tissue distribution
- Extracellular components
- Cell-surface proteins with which they associate
Collagen type examples (3)
Type I - Muscle, tendons, skin bone
Type II - Cartilage
Type V - Cell surface, Hair
What is connective tissue composed of
Water, fibroblasts, fibrocytes, elastin, collagen, ground substances
all are constantly replaced
How does collagen adapt to training?
increased fibril diameter
increased fibril number
combined = increased density
What is the benefit of collagen adaptions?
Increases tendon stiffness which therefore increases ground reaction force (Newtons second law)
