Lesson 4 Flashcards
What are the 5 factors that contribute to muscle mass development/strength?
- genetics
- NS activation
- physical activity
- nutritional activity
- endocrine influences
- environmental factors
What are the 3 muscle adaptations that increase strength of muscles?
- hypertrophy: PCSA and hyperplasia
- increase proportion of Type II muscle fibers
- myofilament packing: b/c increase number of myofilaments means increased crossbridges
Describe how PRT affects hypertrophy and what else you need to train w/ new muscular size and why.
- PRT creates adaptive response in muscle, b/c it creates more efficient translation of mRNA to mediate stimulation of myofibrillar protein synthesis
- need aerobic training b/c number of mitos stays the same during PRT, but protein numbers have increased
Is it hypertrophy or hyperplasia in muscles?
hypertrophy - result of increase in fiber size, not number
What fiber type transformation can PRT have on muscles?
Type IIB - high F, but decrease oxidative -
to Type IIA (slightly less F, but increase oxidative, so less fatiguable)
Why can you only transform within same fiber type?
- the type of motor N innervating the muscle fiber dictates the muscle fiber’s characteristics
- N cross-innervation and artificial E-stim can reverse metabolic and contractile profiles of muscle fibers
How do neural and hypertrophic factors contribute to strength gains?
neural adaptations: 0-4 weeks
hypertrophic adaptations: 6+ weeks
What are the 5 neural changes in strength?
increased:
- number of motor units recruited
- firing rate of MU’s
- MU synchronicity
- activation of synergist muscles
- inhibition of antagonists
Does RT reduce fat or increase CV fitness?
- it can reduce percent of body fat when you increase muscle mass, but doesn’t reduce the amount of fat
- no change in CV
What is EPOC?
in exhaustive exercise, the exercise O2 requirement significant exceeds actual exercise O2 consumption, so even during recovery need to replace depleted O2 deficit and therefore we use increased O2 after exercise for about 3 hours
-we use ATP w/o O2 in phosphagen system during exercise, so we replace the used ATP afterwards by increased O2 consumption
What are factors that contribute to EPOC?
- resynthesize ATP and convert lactate to glycogen
- oxidize lactate in E metabolism
- restore O2 to myoglobin
- thermogenic effect of increasing core temp and hormones
- effects of increased HR, ventilation
How does EPOC affect metabolism?
can have increased metabolism for about 38 hours after RT
What accounts for majority of strength gain in younger and older novices?
learning and familiarization (5-10%) due to neural adaptation
How many calories do you burn a min with exercise?
6-10 kcal
What does training at fast and slow velocities improve?
slow: improvement across all speeds
fast: most improvements only at high speeds
Why is there neural inhibition? What its derived from?
- may be a protective reflex
- derived from unpleasant past experience, overly protective home environment, fear of injury
What are different techniques to increase supramaximal performance by increasing motor N recruitment?
- motivation
- encouragement
- excitement
- disinhibitory drugs
- hypnotic suggestion (most effective)
How are NMJ’s adapted in endurance training of animals?
- increase size and complexity
- increase presympathetic ACh stores and isozymes of ACh delays NMJ fatigue
What does an EMG do?
study neuromuscular adaptations and reflects both quality/quantity of electrical activity generated
In early and late stages of RT program, how does EMG respond? What about w/ eccentric vs concentric?
early stages: EMG will increase due to neural adaptations
late stages: EMG doesn’t increase b/c hypertrophic
eccentric: about 25% less than EMG for same absolute workload w/ concentric contraction, because use less ATP
What are different muscle fiber type classifications?
-red = myoglobin
Type I: slow twitch, low tension and fatigue resistant
Type IIA: fast twitch, mod force and fatigue resistant
Type IIB: fast twitch, high force and high fatigue
What is the size principle of muscle fiber recruitment?
-slow oxidative MU’s (Type I) are recruited first b/c require less excitation to reach threshold
What type of contraction uses less ATP?
eccentric
What is the importance of eccentric muscle contraction?
- low metabolic cost
- increased strength production and hypertrophic adaptations
- easier to perform
- implications for rehab
What is myofibrillar disorganization and what happens to F transmission?
- breakage of cytoskeletal proteins at the Z-disc
- lose some F b/c physical change to sarcomeres make them weaker
Why do you feel DOMS?
- microscopic tears
- osmotic pressure changes = fluid retention
- muscle spasms
- overstretching CT
- acute inflammation
- altered calcium regulation
What is exertional rhabdomyolysis?
myoglobin spills over from blood to urine- causing renal failure
-Coca-Cola colored urine!
When does DOMS usually occur and how long does it last?
high-intensity or long-term eccentric/plyo
-peaks at 36-48 hours and last 3-4 days
What are 2 mechanisms of muscle damage?
1) -early in exercise (A b/c oxidative fibers not as stiff
2) -same first step
- mitos lose calcium buffering capacity b/c unable to regenerative ATP
- increase intracellular calcium results in activation of calcium-activated proteases and lysozymes
- –explains importance of oxidative capacity of muscles
What happens in the SR in muscle damage?
- decrease in pH
- increase ADP, Pi
- altered ionic balance and temp
- -all factors may decrease calcium uptake and release, resulting in high calcium in cytosol, leading to decrease F capacity and soreness
What are markers for muscle damage?
creatine kinase myoglobin troponin LDH alanine aminotransferase
What is pain from in eccentric exercises?
inflammatory response stimulating very small sensory N endings in muscle and muscle spindles
How does a single exercise bout effect subsequent exercise?
existing muscle soreness doesn’t exacerbate subsequent muscle damage or impair process, in fact it can protect against new soreness for up to 6 weeks
How much strength loss can occur after 1 bout of eccentric exercise in novice?
25-50% decrease for several weeks
What is the “popping sarcomere” theory?
- sarcomeres naturally rest at slightly different lengths, which means some longer sarcomeres have less filament overlap and thus generate decreased F compared to shorter counterparts
- when long sarcomere “pop” apart, replaced with 2 short sarcomeres in series to help prevent future muscle damage
What is purpose of placing sarcomere in parallel or in series?
- in parallel: increases F
- in series: protects against muscle damage from tension
