muscles contraction and training

Question 1

Name the 2 types of fatigue

Answer 1

central and peripheral

Question 2

Where does central fatigue com from

Answer 2

within the nervous system

Question 3

What is lost during central fatigue

Answer 3

loss of motor complex excitability

Question 4

Where does the central fatigue reflex come from

Answer 4

reflex inputs from metabolo-receptors

Question 5

Where does peripheral fatigue come from

Answer 5

in muscles

Question 6

What fails during peripheral fatigue

Answer 6

failure of crossbridge formation and failure of atp generation

Question 7

What type of forces do muscles produce during central fatigue

Answer 7

normal forces

Question 8

What type of forces do muscles produce during peripheral fatigue

Answer 8

smaller forces

Question 9

Desscribe the 2 steps of muscles response to training

Answer 9

• Neural phase
o Lasts for the first 4-6 weeks of training as the activation of the motor units improves
o ‘Hypertrophic’ as large motor units grow
o Connective tissues in muscle strengthen to handle an increased force
o Steroids can be used  risks injuries to muscles as although the muscle I getting stronger, the connective tissue surrounding them are not ie. Tendon therefore they are more susceptible to injury
o Neural phase response is part opf the CNS
o Involves an increased in type 2b (FF) muscle fibres, and higher maximal firing rates
o Many untrained people do not fully activate their largest motor units (2b), especially during rapid shortening of the muscle
• Hypertrophy
o Large motor units (Type 2b) grow
o After strenuous training, Growth hormone is secreted along with IGF, Insulin and testosterone, resulting in all of these levels being elevated
o Hypertrophy is slow and starts with new contractile filaments being added to the already existing myofibrils, as the fibril splits along the tubule so it is broken into 2. This results in an increase in fibrils, causing extra growth in the muscles to occur

Question 10

What steps of mechanism that provide energy for muscles are affected by fatigue

Answer 10

4, 5 and 6

Question 11

Why are these steps effected by fatigue

Answer 11

1. Muscle action potentials have a high firing rate  this high rate means that potassium ions are released at 50 times a second, resulting in an accumulation in potassium
2. Potassium accumulations turns on metabolically sensitive nerve endings
3. 1st cause of fatigue – the accumulation of potassium which makes t-tubules unexcitable and impairs the contraction coupling
4. Potassium is restored in stage 6, therefore fatigue recovery is fairly rapid.

Question 12

Describe muscle mass due to strength training

Answer 12

increases

Question 13

Describe muscle mass in response to endurance training

Answer 13

decreases

Question 14

Describe some effect of endurance training

Answer 14

S AND FFR motor unit hypertrophy occurs, number of mitochondrua uncrease and there is an increased oxygen supply un the body

Question 15

Describe some effects of strength training in the body

Answer 15

Early changes, better motor unit activation and FF fibre hypertrophy

Question 16

Define a motor unit

Answer 16

Single motor neurone and all the muscle fibres it innervates

Question 17

How many types of motor units are there

Answer 17

3

Question 18

name the 3 motor units

Answer 18

S (type 1), FFR(2a), FF(2x)

Question 19

What does S stand for

Answer 19

slow

Question 20

what does ffr stand for

Answer 20

fast fatiguing resistant

Question 21

What does ff stand for

Answer 21

fast fatiguing

Question 22

Describe FF motor units on a graph

Answer 22

larger twitch response
faster rise
faster fatigue

Question 23

Describe S motor units on a graph

Answer 23

smaller twitch
smaller rise
slower fatigue

Question 24

describe muscle metabolism

Answer 24

When the ATP generated from creatine phosphate is depleted, the immediate requirements of contracting muscle fibers force anaerobic respiration to begin. Anaerobic respiration can supply ATP for about 30 seconds. If muscle contraction continues, aerobic respiration, the slower ATP‐producing pathway, begins and produces large amounts of ATP as long as oxygen is available. Eventually, oxygen is depleted, and aerobic respiration stops. However, ATP production by anaerobic respiration may still support some further muscle contraction. Ultimately, the accumulation of lactic acid from anaerobic respiration and the depletion of resources (ATP, oxygen, and glycogen) lead to muscle fatigue, and muscle contraction stops

Question 25

What does exercise that requires high power but lasts a short time cause

Answer 25

contraction to only last a few seconds and ATP is regernated by the breakdown of creatine phosphate

Question 26

Describe low power exercise which lasts a moderate period of time

Answer 26

Depletion of glycogen

Question 27

Describe long duration exercis

Answer 27

utilises lipids almost entireley

Question 28

outline refuelling after exercise

Answer 28

• Feeding after exercise is important for a rapid recovery
• Eating during exercise during long duration ie. Tour de france – however time needs to be given for the food and atp to be absorbed in order for it to have an actual effect
• Muscles, like any other cell in the body, must make energy in order to function properly. Muscles use adenosine tri-phosphate (ATP) directly for contractile activities, however, they do not use it at a constant rate. This is because they switch between a contracted and relaxed state depending on whether or not they are in use.
• Despite the crucial role of ATP, skeletal muscles do not store a great deal. However, in order to function well, a good supply of ATP is necessary as it is quickly broken down and reused during the contraction cycle. Muscles regenerate ATP in three ways: direct phosophorylation using the following: creatine phosphate, anaerobic respiration, and aerobic respiration.
• ATP is a nucleotide used as the major energy currency of all cells. ATP is used in energy transfer and in muscle fibers, and provides the energy for the contraction cycle. A molecule of ATP composed of the pentose sugar, ribose, a nitrogenous base, adenine, which together form the molecule adenosine, and three phosphate groups. To release energy, ATP is catabolized by removing a phosphate group. To store energy, a phosphate group is added onto a molecule called ADP, and together, these make ATP.