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
Lecture 10:
When discussing resistance training & diet, how much protein should be consumed & when?
- consume 1.6-1.7g of protein per kg of body weight per day to increase muscle mass
- consume 20-25g protein after resistance exercise for increased muscle growth (as protein synthesis greatest after exercise)
Lecture 10:
What is protein synthesis with resistance training controlled by?
Controlled by mTOR (mechanistic target of rapamycin) - integrates input from insulin, GF, & amino acids while dictating the transcription of mRNA
Lecture 10:
What occurs in the absence of mTOR in terms of protein synthesis?
Absence of mTOR means no protein synthesis can occur, no matter what you eat or exercise type
Lecture 10:
Resistance training for children and adolescents - myth vs truth?
Myth = resistance training is unsafe due to growth & hormonal changes
Truth = it is safe with proper safety guards - children can gain both strength & muscle mass
Lecture 10:
What are 3 benefits of resistance training for the elderly population?
Helps restore age-related loss of muscle, improves quality of life and health, & helps prevent falls
Lecture 10:
What is strength increase dependant on in elderly?
Increases in strength is primarily dependent on neural adaptations (no diff across sex/race)
