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App Phys week 5

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bethdrysdale94's version from 2017-01-27 17:18

Section 1

Question Answer
What is the equation for power?power = force x velocity
When is maximum power generated?optimum velocity (Vopt) - 30% Vmax. optimum crossbridge formation between myacin and actin
What is Vmax?maximum of shortening velocity - max rate of cross bridge turnover
for isometric force, when is max strength reached?when velocity is 0
If you have more crossbridges, what effect does this have on force?increased force, crossbridges are independent force generators
What effect does an increased cross sectional area of quadriceps have on their isometric force?increased CSA, increased isometric force max
What is penated muscle?fibres don't angle in direction of insertion (penation is measured as an angle)
what is the limitation of an anatomical cross sectional area?doesnt consider angle of penation
physiological CSA considers what?angle of penation
What is the relationship between muscle volume and torque?positive correlation
What happens to the pennation angle as muscle becomes thicker in triceps brachii?angle increases
What did Fukunga et al 2008 look at in body builders and weightlifters?pennation angle, (aka fascicular angle). Larger pennation angle can be associated with lower force capacity so important to improve muscle strength and not just size. 45 degrees is supposedly optimal although there is no evidence for this
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Section 2

Question Answer
Fukunga 2008 summarybodybuilders have bigger muscles, overall strength - body builders are stronger and have a bigger penation angle. If force is normalised (force/CSA), power athletes are actually stronger in comparison to body weight
Fukunga 2008 findingsbigger pennation angle = lower normalised force (force/CSA)
Meijer study summarybodybuilders do less intense workouts with more reps. athletes do more intense workouts with less reps. measured single fibre contractile properties. measured speed of shortening and worked out power
Meijer study findingsbodybuilders again had lower normalised force. peak power ratings - 1st athletes, 2nd control group, 3rd bodybuilders
How does sarcomere length affect speed of contraction?longer muscles contract quicker, speed =distance/time. longer sarcomeres travel 2xdistance in the same time frame
What is the order of muscle fibre types from slowest to fastest?Type I, type IIa, type IIx
What are type I and type II muscle fibres?Type I = slow twitch oxidative. type II = fast twitch glycolytic
What muscle types will sprinters and endurance runners have?sprinters = type II, endurance = type I
After a spinal injury, what muscle type does muscle revert to?type IIx, default gene expression is type IIx
What did Abe 2000 say about sprinters and fascicle length and pennation angle?sprinters have longer fascicles/sarcomeres - contract quicker. Pennation angle is lower, optimum for speed = 0degrees
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Section 3

Question Answer
What does the speed of muscle depend on?cross bridge cycling rate, controlled by mATPase activity which is a function of the myosin heavy chain.
What was Andersen and Aagaard's study?muscle biopsies of two different subjects, pre training, 3 month during/post training, and a detrained biopsy. Subject B began with IIx, which shifted to type IIa and type I with resistance training. IIx reappeared after detraining. Only 10% shift, which is BIDIRECTIONAL
What did Andersen and Aagaard say about the overshoot phenomena?more IIx after detraining. sprinters embark on a reduction/taper training programme as there are theories behind IIx% increasing even after training.
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Section 4

Question Answer
What doesnt occur in humans with increasing strength?muscle hyperplasia (increase in number of fibres). instead hypertrophy occurs (increase in CSA of fibres)
What occurs in hypertrophy?myofibrillar protein accumulation. change in balance between synthesis and breakdown. >> increase in transcription and translation.
What happens to the rate in protein synthesis after resistance exercise?elevated for up to 24 hours. degradation of muscle protein is also elevated but to a lesser extent so NET GAIN IS INCREASED
What does FSR stand for?fractional synthetic rate
Kumar et al 2009 %1RM and FSRmuscle synthesis has a dose-response relationship: FSR plateaus at 60-70% 1RM, but anything lower does not provide enough stimulus for max FSR to be reached.
what is a satellite cell?stem cell for skeletal muscle
What causes activation of satellite cells?IGF peptide kick starts muscle repair or hypertrophy
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Section 5

Question Answer
What is IGF peptide?endocrine/autocrine hormone that triggers a cascade pathway
What cascade does IGF peptide trigger?protein synthesis, MAINLY REMEMBER mTOR (mammalian target of rapamycin). rapamycin is a cofactor. mTOR is the rate limiting factor of muscle protein synthesis.
west et al 2010resistance training in arm, increased levels of hormones (GH and IGF) but there was the same rate of hypertrophy in low and high hormone environments - circulating hormones had no effect on protein synthesis
what is the actual stimulant of protein synthesis?exercise itself stimulates mTOR which switches on protein synthesis. amino acid feeding also stimulate mTOR (dietary input)
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Section 6

Question Answer
What are the ACSM guidelines for hypertrophy?8-12reps at 60-70% of 1RM, usually to fatigue. 1-2 minute rest period between sets
Are high weights necessary?3 conditions: 90% 1RM to fatigue, 30% 1RM work matched to 90FAIL, 30% 1RM to fatigue. >>> 30FAIL as effective as 90FAIL in stimulating protein synthesis. suggests the main stimulus is fatigue
What did Vernon Coffey study about concurrent exercises?do they interfere with each others adaptations - no conclusion as of yet: endurance stimulates PGC-1alpha (mitochondrial biogenesis, angiogenesis). resistance stimulates mTOR (translation, ribosomal biogensis) BUT PGC-1alpha and mTOR are interlinking pathways. not enough evidence, need to do the study over years
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