Lecture 20 : Sprinting Mechanics of Performance and Fatigue

Question 1

sprint running and rowing are very different in terms of sprinting

explain how their angular velocity, peak force, application times and SSC differ

Answer 1

sprint running : very high angular velocities, peak forces and short application times, fast SSC

rowing : low angular velocities, high peak forces, long applications times, slow SSC

Question 2

when you become an elite athlete shorter application windows are more influenced by what and longer application windows are more influenced by

Answer 2

shorter more influenced by fibre type

longer more influenced by MVC

as elite athletes indivdual characteristics such as these make more of a difference as they are usually at their ceiling.

Question 3

how do these compare in terms of trainability

strength
RFD
RR
elasticity

Answer 3

strength is highly trainable, RFD, RR and elasticity are less so

Question 4

how does contraction duration change when accelerating from a static position

Answer 4

contraction duration is initially quite long, gets shorter with each subsequent contraction so you have less time to apply force

Question 5

there is an optimal point of combination of contractile speed and force which optimises power, what happens if speed increases above this

Answer 5

power can diminish

Question 6

increasing PCr stores does what for one off sprints

Answer 6

nothing.

Question 7

fatigue usually occurs when in sprinting

Answer 7

in 10s

Question 8

the concept of optimal cadence is

Answer 8

cadence at which peak power is achieved

Question 9

how has the concept of optimal cadence changed track cycling and decreased times

Answer 9

increased gearing size which has allowed athletes to race at cadences that optimise power

Question 10

the faster your sprint the less time for

Answer 10

less time for force application

Question 11

usually reach peak power when in an 100m sprint

Answer 11

about 10 m into the race so power is descending for the rest of it

Question 12

how does the gear change that happened in cycling link to running and why it would be very hard for someone to beat usan bolts time

Answer 12

his long legs…
The gear change analogy explains why you can’t just run faster by moving your legs quicker — you need to produce more force and maintain stiffness, just like pushing a harder gear in cycling.

Usain Bolt’s unique combination of limb length, force output, while still being able to have an increase stride frequency makes replicating his performance incredibly difficult.

Question 13

for a shorter athlete to be able to compete with usan bolt they would need ..

Answer 13

unfeasible proportions (>90% type II) to compete with him

Question 14

Ken Clarke thinks the new 100m world champ will need to be taller than Bolt, but what are the disadvantages to this

Answer 14

power to weight : skeletal mass relative to muscle CSA

aerodynamic drag : larger frontal surface

Question 15

what are two key factors influencing force application at speed

Answer 15

time available for force application (RFD and RR key components)

ability to apply force at high angular velocities

Question 16

what is needed to improve the ability to apply force at high angular velocities

Answer 16

optimise number of sarcomeres in series

Question 17

fast twitch fibres produce more force and power at every speed, when does the advantages of higher proportions of these become more apparent

Answer 17

as speed increases

Question 18

power in short sprinting decreases after how many seconds

Answer 18

2-4

Question 19

conventional literature says that changing excursion angle to modify contact length is not really feasible why

Answer 19

because they say it limits vertical force and can lose efficiency

Question 20

what is the BUT in to the conventional literature saying that changing excursion angle to modify contact length is not really feasible

Answer 20

if we could change the length tension curve of muscle with appropriate training it could work

it would perhaps provide options for increasing horizontal force

perhaps we could bounce efficiently from longer muscle lengths

Question 21

if increasing excursion angles were possible what would the implications be

Answer 21

shorter runners could increase CL and thus increase ground contact time, perhaps negating some of the impulse time advantages of the taller athlete

Question 22

what it the BUT for the shorter runner if we were able to increase excursion angles

Answer 22

could increase GCT

but

would have very high angular velocities which would require a lot of fast muscle or sarcomeres in series

nonetheless there may be some advantage to increasing excursion angles

Question 23

some evidence suggests that longer fascicle lengths could what

Answer 23

could be metabolically advantageous by reducing metabolic energy expenditure

Question 24

to change the length tension curve, what type of contraction is most likely to be possible to do this

Answer 24

eccentric training

Question 25

more sarcomeres in series has an additive effect on what

Answer 25

contraction velocity perhaps more influential on high speed force production than fibre type

Question 26

there are some suggestions that more sarcomeres in series negatively impacts

Answer 26

negatively influence initial RFD

Question 27

how do we add and maintain sarcomeres in series

Answer 27

strength train - especially eccentric long length isometric training

Question 28

does the number of sarcomeres in series detrain fast or slow

Answer 28

rapidly if stimulus removed altogether but can be maintained with small volumes of high intensity stimulus

Question 29

what usually happens in an elite sprint career

Answer 29

performance usually plateus typically around 22

Question 30

how could sprint time be improved after 22 instead of plateu performance

Answer 30

'change gears' or increase ground force to improve stride length

Question 31

shorter ground contact times require an increase in stiffness or elasticity

Answer 31

an increase in stiffness you want a stiff spring to stimulate high rate of force development

Question 32

fascia develops where and what is this advantageous for

Answer 32

long lines of stress advantageous in maintaining efficiency, energy return and speed of contraction

Question 33

fascia responds to

Answer 33

repetition