Biomechanics Feb 4 - intro and neural adaptations to training

Question 1

A group of sarcomeres make up a ___

Answer 1

myofibril

Question 2

A group of myofibrils make up a ____

Answer 2

m fibre

Question 3

At the level of the sarcomere, what are the two basic tenets (force - __ relationships) that make up the BL tenets

Answer 3

force v
force L

Question 4

In addition to the MTU, what is the neuro make up of the muscle look like/mechanisms at play?

Answer 4

mo unit which is the mo neuron and the fibres it innervates

Question 5

Each muscle has ++ motor __

Answer 5

units

Question 6

Constraints based approach of our system - redundancy in degrees of freedom of movement, what does this mean?

Answer 6

multiple ways to do a single task

Question 7

Determinants of strength and power - what factors determine force?

Answer 7

m mechanics
neural involvement
morphology
m environemnt

Question 8

Myosin heavy chain fibres- slow - what type are these and what do they help with?

Answer 8

type I
antigravity with w bearing and sustaining movement

Question 9

Myosin heavy chain fibres- fast oxidative - what type are these and what do they help with?

Answer 9

IIa/IIx
sustained locomotor

Question 10

Myosin heavy chain fibres- fast glycolytic - what type are these and what do they help with?

Answer 10

IIb, IIx
burst power

Question 11

What determines how fast type I, IIa, b, x fibres contract?

Answer 11

ATPase - connection and reconnection

Question 12

Factor 1: muscle mechanics: how does this effect force? (basic terms)

Answer 12

F-L relationship
F-v
F-v-power

Question 13

Fmax depends on ? and ?

Answer 13

CSA
vmax/mo unit type

Question 14

Factor 2 of m force contributor: morphology - what are the two subtypes of interest in this?

Answer 14

CSA
pennation angle

Question 15

Cross sectional area - what causes more force?

Answer 15

more contractile pro = more cross bridge = more force

Question 16

Pennation angle: what is this?

Answer 16

angle between tendon and m force

Question 17

How does pennation angle increase force?

Answer 17

increase in angle means m fibres operate at better position but decr shortening velocity potential/vmax

Question 18

How does increased pennation angle effect vmax?

Answer 18

decrease

Question 19

Factor 3 effecting muscle force: neural inputs - what are the different components of the feedback mechanism?

Answer 19

m spindle modulates and at golgi tnedon organ
- intra and inter muscle coordination: how active agonist, antagonist are
-inter m + segments proximal to distal sequencing

Question 20

What two components determine neural activity/drive?

Answer 20

number of recruited mo units and firing frequency

Question 21

How is neural activity often measured?

Answer 21

EMG

Question 22

In EMG, bigger peak and trough mean?

Answer 22

incr neural activation

Question 23

In the short term, what seems to increase the most strength training enhancements when comparing neural drive vs CSA vs pre training

Answer 23

neural drive!
> csa
> PT

Question 24

The stronger an athlete is … how does this effect adaptation?

Answer 24

less adaptability

Question 25

If untrained, how does agonist antagonist coactivation seem to occur vs in a highly trained athlete?

Answer 25

high level of coactiv in low tr vs highly trained athlete has less of this

Question 26

Why would we expect to see a high level of coactivation of agonist and antagonist in athletes who are untrained?

Answer 26

stability protection and breaking in ballistic movement

Question 27

We tend to see the most adaptation in a short period from untrained individuals via neural adaptation. How does this neural drive change with detraining (Hakkinen 1983)

Answer 27

lost quickly force production ability decrease less, so likely some morphologic changes from initial bit are protective

Question 28

EMG vs torque graph: what changes indicate neural adaptation?

Answer 28

increase y axis

Question 29

EMG vs torque graph: what changes indicate morphologoical change

Answer 29

increase x axis

Question 30

Increases in neural adaptation are often due to firing frequency ___ and or mo unit ___

Answer 30

increase recruitment

Question 31

How does the reflex mechanism work in str training and plyometrics?

Answer 31

increase excit of m spindle (incr facilitation) decr excit and desens golgi tendon organ (to decr inhibition) overall decr inhib for excitatory action

Question 32

Pre-activation (ex pre activ prior to ground contact in plyos) may be hlepful for incr force production why?

Answer 32

may benefit s+C by modulating stiffness may protect against injury through incr stability

Question 33

Explosive strength: on a joint force vs time graph, how is this shown?

Answer 33

inverted U max strength at peak of inverted U rise on first part of U indicates explosive strength

Question 34

Explosive str defn

Answer 34

how much of max strength can generate over short timeframe

Question 35

Rate of force development/RFD defn

Answer 35

specific measure where explosive strength in quality to teast out

Question 36

Common metrics used to describe explosive strength (3)

Answer 36

force at given time point RFD: change in f/change intime - steeper slope = higher rate of force development impulse: area under the curve

Question 37

Common ph used in research used to determine overall explosive strength production: early vs mid vs late

Answer 37

0-50ms 50-100 >100

Question 38

What two main pieces are considered in rate of force development?

Answer 38

Max force time to achieve a given percentage of max force

Question 39

RFD: max force determinants

Answer 39

due to max strength due to CSA

Question 40

RFD: time to achieve a given % of max F - 3 parts?

Answer 40

neural activation insttrinic contractile properties tendon stiffness all determined in some part by contraction speed and type

Question 41

Max force ultimately determined by what "phase" of explosive force development

Answer 41

late >100ms

Question 42

Early ph force development typically determined most by what concept?

Answer 42

neural drive and twitch (force by single stim/instric contraction properties of m fibre)

Question 43

Mid ph force development typically determined most by what concept?

Answer 43

intrinsic - voluntary activation

Question 44

Importance of intent in training: Tillin 2014 paper took isometric training where group 1 trained as hard and fast as possible vs conventional group at 75% max voluntary force (ie greater time under tension at lower intensity). What were the findings of force initially and at 12 weeks pf training?

Answer 44

both incr force but conventional f 2x > than gr 1 0-150ms only explosive gr increased time 0-50ms (neural) at 12 weeks: matched tr type - conventional only incr rate at 150 whereas group 1 increased rate 0-50, 50-100 and >100 CSA changed in conventional group, not group 1

Question 45

Interesting note on training type IIx fibres - can we do this?

Answer 45

not really likely fast enough to train this so ultimately train IIx--> IIb moreso