Week 5: Neuromuscular Adaptations to Exercise Training Flashcards
What are the neuromuscular goals of training?
- Enhance musculoskeletal health (fitness, quality of life, independent living, rehabilitation)
- Improve sports performance
- Change body aesthetics (bodybuilding)
What are some muscular health benefits of neuromuscular training?
- Develop appropriate muscle mass for health
- Countermeasure to muscle atrophy & weakness
- Enhance muscle metabolism
- Increases in muscle performance
What factors influence neuromuscular adaptations with exercise training?
- Initial fitness level
- Genes
- Training program characteristics
How do different types of resistance training equipment affect movement and resistance?
- Freeweights & barbells and cam devices/pulley systems has constant resistance, movement speed varies through ROM
- Isokinetic devices has constant speed movement, resistance varies through ROM
How do neural changes compare to morphological changes during training?
Neural changes occur early in the training program.
Rate of strength improvement is much greater than can be explained by muscle size changes
Motor skill/learning effects contribute to greater increases in dynamic strength over isometric strength.
Crossover effects: Training one leg can improve strength in the other leg (valuable in rehab).
How do neural contributions change muscle force? (3)
- Change motor unit recruitment patterns (greater efficiency & specificity of recruitment, improvements in motor skills)
- Change motor unit synchronisation (increase synchronisation for maximal & near efforts, decrease synchronisation for submaximal activity)
- Decrease central inhibition for voluntary efforts (“central reserve”, can be tested with electrical stimulation)
How do morphological changes contribute to muscle force?
- Muscle force increases with increase in muscle size
- After 8 weeks training, increases in strength track with muscle size
- Size increases continue for at least 12 months
- Eventually a limit to further increase
What muscle group tends to change more in size during training, and why?
Upper limb may change more due to different androgen receptor density
How does fibre type influence muscle size changes?
Type II fibers have more capacity to increase and decrease in size.
Type II fibers show more change in short-term studies compared to Type I fibers.
What is muscle hypertrophy?
- Increase size of fibres
- Increase myofibril size & numbers (myofibril proliferation)
- Increased protein synthesis
What is muscle hyperplasia?
Increase in number of fibres which may result from eccentric loading
What is one cause of limited flexibility around a joint?
Lack of muscle length in muscle
How can muscle length be increased in fusiform muscles?
Insertion of more sarcomeres in fusiform muscles can increase muscle length
What contributes to reduced flexibility?
- Aging
- Disuse or limited use (lack of use through full ROM or loading)
How can the myofibril content in muscle be increased?
To increase myofibril content, the number of myonuclei must also increase
What happens to myonuclei during detraining?
During detraining, muscle fibers may shrink (atrophy), but myonuclei that were previously added during training are not lost. This is why retraining is easier and triggers faster morphological responses (muscle memory)
What role do satellite cells play in muscle growth and repair?
Satellite cells are the source of additional myonuclei.
Exercise loading stimulates satellite cells to undergo mitosis, producing daughter cells that become new nuclei, allowing the muscle cell to increase in size.
They form the basis of muscle repair.
How do tendons and connective tissues change with training?
- Tendon stiffness increases with training.
- Tendon hypertrophy occurs but is slow.
- The proportion of connective tissue to muscle remains roughly the same.
- Changes in connective tissue organization are still unclear
How does muscle architecture change with training?
- Angle of pennation (AoP) can change.
- The optimum AoP for strength is calculated to be ~45°.
- AoP may increase to 45° with heavy resistance strength training (HRST).
