Exam 3- Lecture 19 Flashcards
What does the quality and quantity of skeletal muscle training adaptations depend on?
- type of stress placed on the muscle
Resistance Training Traditional Paradigm: Maximal development of hypertrophy
moderate to heavy loads, moderate to high repetitions, shorter rest periods, multiple sets per exercise
Total work is high
Resistance Training Traditional Paradigm: Maximal strength development
- high load, low reps, long rest periods
- less total work than hypertrophy programs
Resistance Training Traditional Paradigm: Maximal development of muscular endurance
- very light to moderate load, high reps, multiple sets, very short rest periods
Phillips lab hypothesis for resistance exercise
- high rep/low load (3 sets of 20-25, 30-50%) comparable to low rep/high load (3 sets of 8-12, 75%-90%) for accretion of skeletal muscle mass when taken to volitional failure
Resistance exercise leads to –>
small motor units fatiguing –> recruits larger motor units to continue lifting at required muscle force –> maximal # of recruitable motor units now fatiguing –> reach volitional fatigue
– sufficient stimulus for muscle hypertrophy and strength development also leads to volitional fatigue
increases in strength are due to adaptation in two major factors:
neural factors and muscular factors
neural factors that lead to increases in strength
- increased central nervous system activation
- changes in motor unit recruitment pattern
- reduced central inhibition
muscular factors that contribute to increases in strength
- hypertrophy (increased contractile protein content, results in increased muscle fiber size)
motor unit activation size prinicple
recuit in order of motor nerve threshold (most excitable 1st) and twitch force (lowest 1st): slow twitch to fast twitch as intensity increases
maximal force production depends on:
- recruitment: activating available motor units at the appropriate time and in the most effective order
- summation: activation at a high enough frequency
neural adaptations may include:
increased ability to:
- voluntarily receipt all available motor units for a given task
- recruit at a higher frequency
- synchronization
reduction of CNS inhibition of muscle activation (protective mechanism)
strength can increase independent of:
increase in cross sectional muscle area because of neural adaptations
what plays a major role in adaptation response to resistance training?
type of training protocol and movements involved
explain how muscle hypertrophy follows repair:
hormonal and metabolic response, training status and protocols, protein availability, resistance training activates net protein synthesis, and initially associated with damage to fibers –> repair, remodeling and hypertrophy –> hypertrophic response and fibers less susceptible to further damage
muscle hypertrophy follows repair BUT….
damage is likely not required to stimulate hypertrophic response
exercise tissue have increased sensitivity to what hormones?
- testosterone
- insulin
- GH/ IGF I
how do anabolic hormones promote muscle hypertrophy?
- mechanical overload triggers intrinsic IGF I expression in exercises muscle
- muscle IGF- I promotes satellite cell proliferation, differentiation, fusion into exercised myofiber
- new myonuclei hypertrophy occurs through satellite cells
time course of muscle hypertrophy
- while an increase in muscle protein synthesis begins early in the training program, hypertrophy becomes moderately evident after 8-12 sessions into the program and more obviously evident around 18 sessions or so
- rate of increase is greatest in first 6-12 months of training
determining factors for muscle size
- genetics
- duration
- type of training
review chart of muscle hypertrophy response to a new training program
p 250
what does CHO supplementation during (around) resistance exercise do?
- attenuates rate of glycogen depletion
- increases rate of glycogen resynthesis
- can augment anabolic response to training
3 R’s of Post Exercise Recovery
- Rehydration through fluids and electrolytes
- Refueling through carbohydrates
- Repair through protein
what is the most important variable stimulating net protein accretion?
- the resistance training stimulus
- optimizing nutrition has a small effect on muscle protein synthesis compared to the effect of resistance training itself
does a traditional heavy resistance training program augment aerobic capacity (VO2max)?
NO
type of protocol influences metabolic adaptation
Resistance training oxidative and glycolytic enzyme adaptations
- traditional heavy resistance training (high intensity, low reps, long rest) produces only minor enhancement of oxidative or glycolytic enzyme activity
what does high volume, moderate resistance activity, and short rest periods do?
causes higher levels of oxidative and glycolytic enzymes in fast twitch fibers
immediate energy system adaptations
- CP-ATP stores or creatine kinase activity may be augmented depending on the protocol
- changes in intramuscular glycogen or lipid storage are equivocal (may increase or show no change)
Resistance training-capillary density adaptations
- capillary density is decreased in olympic and power weightlifting
- capillary density is increased in body builders
what are stimuli for neocapillarization probably related to?
- motor unit activation
- physiological conditions
what happens if hypertrophy exceeds neocapallarization?
capillary density decreases
mitochondrial density adaptation in resistance training
- mitochondrial density decreases with resistance training if significant hypertrophy is present –> dilution effect
- type of demand (overload) placed on muscle does not significantly activate oxidative processes –> little systemic adaptation occurs
Resistance training metabolic adaptations
- relatively small alterations in metabolic capacity of resistance trained muscle –> lifting protocol influences degree of metabolic adaptation
how does fiber type composition change in resistance training?
- no significant conversion between type II and type I (slow) fibers
- shift in the composition of type II subtypes
circuit training
- general conditioning regimen combining relatively low resistance, high reparation dynamic resistance
- 8-15 exercise stations
- 30 sec/set
- brief rest (10 sec)
- circuits repeated 2-3x per workout
adaptations to circuit training
- traditional lower resistance, high repetition circuit can result in aerobic capacity improvement of 5-10% and strength improvement in untrained persons
- increased caloric cost of resistance workouts
- can be safely used in cardiac patients
does resistance and endurance training interfere with effects of the other?
- may interfere with maximal strength development
- performance of resistance and endurance training on alternate days may reduce interference with strength development
concurrent training single session:
- 1st exercise should be the one you wish to maximize the result but moderate training levels more important than training sequence
- training programs for health and fitness should be moderate for both endurance and strength training
