Sprint and Power events

Question 1

what is power a product of

Answer 1

force x velocity

Question 2

why can the most force be generated at lower velocities

Answer 2

low velocities allow more time for cross bridge cycling, meaning more cross bridges can be utalised which increases the amount of force that can be generated

Question 3

At what velocity of contraction is power greatest

Answer 3

30% of max

Question 4

what are the two main determinants of muscle strength and what is the relationship between these variables and muscle strenght

Answer 4

size:
bigger muscle = more cross bridges
positive correlation between quads cross sectional area and strength

Architecture:
angle of pennation of the muscle
increases as the size of the muscle increases
optimum angle is thought to be 45

Question 5

explain the difference between anatomical and physiological cross sectional area

for a given muscle which is likely to be larger and why

Answer 5

Anatomical = cross section of the muscles perpendicular axis

Physiological = cross section of the muscles perpendicular fibres

Physiological is likely to be larger because it takes into account the angle of pennation

Question 6

explain the relationship between muscle size and muscle architecture and the significance of this

Answer 6

Larger muscle sizes will have a larger angle of pennation, potentially larger than the ideal angle

larger pennation angle is associated with a lower force production for a given amount of muscle

body builders > size vs weight lifters
also greater total force

but have lower force production when normalised to muscle size

Question 7

Compare the characteristics of muscle fibres of body builders, power athletes and controls

Answer 7

size and total force = BB>PA>control
Normalised force = PA>C>BB

Peak power output (watts/kg) = BB=PA>C
normalised = PA>C>BB

Question 8

describe the relationship between muscle fibre type and speed of shortening

Answer 8

vMax ratio of 1:4 (type I:type II)

isometric force generation capacity is the same but speed of shortening is much greater in type 2

therefore type 2 is able to generate more power

type 2 also has a higher optimum speed of shortening

Question 9

Explain why a longer muscle is able to produce a faster speed of shortening

Answer 9

longer muscle = more sarcomeres in a line

sarcomeres are a set length and contract a set proportion of that length in a set amount of time

so more sarcomeres = more distance of contraction in the same amount of time

speed = distance/time

Question 10

compare the findings of biopsies of sprinters muscle with the muscle of average people and endurance runners

Answer 10

sprinter was 80% type 2, half of that was 2x

average = 50% type 1, 45% type 2a, 5% type 2x

endurance = mainly type 1

sprinters have type 2a fibres which can produce more force than other people’s 2a

they also have longer muscle fibres which have a faster shortening velocity

Question 11

outline evidence of how you can change the fibre type of muscle to increase the velocity of contraction

Answer 11

aim is to increase amount of type 2 fibres, but this is strongly linked to genetics

12 weeks of heavy load resistance training
3 months detraining period
biopsy at 0, 12 weeks and 3 months

following training period 2x was replaced with 2a

after detraining period 2x had returned and there was more than had been present at 0 weeks

Question 12

give some critique of the work on changing muscle fibre type by resistance training

Answer 12

athletes don’t undergo a period of detraining

don’t know what happens between end of training and end of detraining

don’t know if muscle fibre change remains

Question 13

describe briefly how increases in muscle size can be achieved

Answer 13

training causes an increase in muscle synthesis for 24 hrs ish
there is also an increase in breakdown but to a lesser extent therefore get a net gain

dose response relationship between training intensity and size increase up to around 60% 1RM

Question 14

outline the stimulus for muscle hypertrophy

Answer 14

IGF peptide stimulates satellite cells to initiate tissue repair and hypertrophy

sets off a cascade of proteins leading to the activation of mTOR

mTOR activates ribosomes to promote protein synthesis

Question 15

outline the methods of the trial challenging the guidelines for muscle hypertrophy training

Answer 15

three groups

90% 1RM to fatigue
30% 1RM to match work done by group 1
30% 1RM to fatigue

protein synthesis response was measured

Question 16

outline the findings of the trial challenging guidelines for muscle hypertrophy training

Answer 16

30% to fatigue did the greatest volume of work
also spent the most time with muscle under tension

had same amount of protein response as 90% to fatigue
high weight potentially not neccessary

but did not see as much translation into hypertrophy and strength gains as 90% group