Lecture 10 Flashcards
Lecture 10:
When muscle size increases, what happens to strength? When size decrease?
Increase in muscle size (hypertrophy) = increase in muscle strength
Decrease in muscle size (atrophy) = decrease in muscle strength
Lecture 10:
What are 2 sources of strength gains?
1.) increase in muscle size
2.) altered neural control levels
Lecture 10:
How does neural control impact strength gain?
Strength gain cannot occur without neural adaptations (via plasticity)
- strength gain also cant occur without hypertrophy
*strength is a property of the motor system not just the muscle
Lecture 10:
What are essential elements of strength gain?
Neural Control, Motor unit recruitment, stimulation frequency, & other neural factors
Lecture 10:
How are motor units recruited normally?
Normally recruited Asynchronously
Lecture 10:
How are motor units recruited when wanting strength gains?
Synchronous recruitment - improves muscles ability to generate force & rate of force development
- facilitates more forceful contractions & capability to exert forces steadily
Lecture 10:
What is another way motor units cause strength gains?
Greater motor unit recruitment may cause strength gains due to increased neural drive on max contraction, increase ferquency of neural discharge & decreased inhibitory impulses
Lecture 10:
What is an example for Autogenic Inhibition?
Normal intrinsic inhibitory mechanisms like; the Golgi tendon organs that inhibit muscle contraction when tendon tension’s too high so damage is prevented
Lecture 10:
What occurs to inhibitory impulses when training?
Inhibitory impulses decreased by training so muscle can generate more force
Lecture 10:
When discussing other neural factors of Muscle strength gain, how does coactivation alter this?
Reducing Co-activation of agonist & antagonist muscles causes strength gain as more strength can be produced as antagonists don’t oppose agonist force as much
Lecture 10:
Define Muscle Hypertrophy
Increase in muscle size
Lecture 10:
What are the 2 types of muscle hypertrophy?
Transient & Chronic
Lecture 10:
what is Transient Hypertrophy?
1.) Transient - occurs after exercise due to edema formation from plasma fluid build up & doesn’t last long (gone in a few hours)
Lecture 10:
What is Chronic Hypertrophy?
- 2 types?
2.) Chronic - long-term structural change in the muscle & is the actual structural changes of muscles
- can be fibre hypertrophy (each fibre gets bigger) or fibre hyperplasia (more fibres added to muscle)
Lecture 10:
What type of training allows for maximized chronic muscle hypertrophy?
High-velocity eccentric training as it disrupts the sarcomere Z-lines (protein remodeling)
- concentric training may limit strength gain (hypertrophy)
- caused by both high-rep/low-load and low-rep/high-load training
Lecture 10:
What physically happens to the muscle during fibre hypertrophy?
There are more myofibrils, more actin & myosin filaments, more sarcoplasm, & more connective tissue
- resistance training increases protein synthesis (synthesis decreased & degradation increased when exercising & opposite after exercise)
Lecture 10:
What 3 hormones facilitate fibre Hypertrophy?
- Testosterone — (natural anabolic steroid) causes large increase in muscle mass
- Growth Hormone
- Insulin-like Growth Factor 1 (IGF-1)
*elevated levels post exercise not required for anabolism & strength gain
Lecture 10:
When discussing neural activation & hypertrophy, what occurs during short-term increase in muscle strength?
Short-term increase in muscle strength = increase in 1 rep max due to increased voluntary neural activation (critical in first 8-10weeks)
Lecture 10:
When discussing neural activation & hypertrophy, what occurs during long-term increase in muscle strength?
Long-term increase in muscle strength is associated with significant fibre hypertrophy & a net increase in protein synthesis (requires time) - major factor after first 10weeks
Lecture 10:
What is muscle atrophy & what occurs to muscles during inactivity?
Atrophy = major change in muscle structure & functions (decrease in muscles) & caused by reduced activity
- limb immobilization & retraining studies support this
Lecture 10:
What occurred in the Limb Immobilization studies?
- after 6hours? First week?
- Major changes seen after 6h —> reduced protein synthesis & muscle atrophy initiated
- First week (3-4% strength lost/day) —> decreased muscle size (atrophy) & decreased neuromuscular activity
- type I more effected than type II but both reversibke
Lecture 10:
What does de training lead to?
Detraining = decreased 1 rep max but lost strength can be regained in ~6weeks
- meeting training goal = maintenance resistance prevents retraining - maintain strength & 1rm (even with reduced training frequency)
Lecture 10:
What are a few conditions that allow fro fibre type conversion?
Fibre type conversion is possible under conditions like;
- cross-innervation
- chronic low-frequency stimulation
- high-intensity treadmill or resistance training
Lecture 10:
What does resistance training increase?
Increases protein synthesis
