ES Questions Flashcards
What is a motor unit ?
The motor neuron & the number of muscle fibres
that it innervates is called a motor unit.
Explain the process known as reciprocal inhibition.
This is the process when skeletal muscles
work in pairs to create movement.
Agonist
The muscle that contracts, creating the movement.
The agonist is called the ’prime mover’ and assisting
muscles are called ‘synergists’.
Antagonist
The muscle that relaxes, allowing the movement to occur.
Name the three types of muscle found in the body
and briefly define each.
Muscle fibre types:
Smooth – found in the intestines, involuntary
Cardiac – found in the heart only, striated cells, involuntary
Skeletal – Voluntary, found throughout the body for movement, can be Fast and slow twitch fibres
What causes fatigue?
Decreased Energy ATP-PCr Phosphocreatine depletion warm-up & pacing decreases fatigue “hitting the wall” = no energy glycolysis Glycogen depletion in used muscles depletion in certain muscle fiber types depletion of blood glucose oxidation a lack of O2 increases lactic acid bicarbonate & cool down a causitive factor of muscle strains Accumulation of Metabolic Bi-products (acidosis).
Explain the graded muscular response
skeletal muscles possess.
An important characteristic of skeletal muscle is its ability to contract to varying degrees. A muscle, like the biceps, contracts with varying degrees of force depending on the circumstance (this is also referred to as a graded response). Muscles do this by a process called summation, specifically by motor unit summation and wave summation.
Define Heart rate, Stroke volume and
Cardiac output
Heart Rate: is the number of times your heart beats
per minute and can be measured by taking your pulse
Stroke Volume (SV): is the amount of blood pumped
by the heart each beat and is measured in millilitres.
At rest stroke volume is 70-90mls per beat in an
untrained athlete and 100-120mls per beat for a
trained athlete.
Cardiac Output: is the amount of blood pumped by
your heart each minute and is expressed in litres/minute.
Cardiac output = stroke volume x heart rate
Outline 3 factors which affect a person’s ability
To adapt to aerobic training program
Heredity accounts for between 25% and 50% of the
variance in VO2 Max values.
Age-Related decreases in VO2 Max might partly
result from an age-related decrease in activity levels.
Gender plays a small role (10% difference) in the
VO2 Max values of male and female endurance athletes.
There will be RESPONDERS (large improvement)
and NONRESPONDERS (little improvement) among
groups of people who experience identical training.
The greater the Specificity of Training for a given sport
or activity, the greater the improvement in performance.
Describe the characteristics of skeletal muscles
Excitability - responds to stimuli (e.g., nervous impulses)
Contractility - able to shorten in length
Extensibility - stretches when pulled
Elasticity - tends to return to original shape & length after
contraction or extension
Hypertrophy – the ability to get bigger in size if worked regularly
Atrophy – the ability to get smaller in size if not used regularly
For training purposes, why is it important to
understand the energy system contribution of
your sport ?
So that the correct energy systems can be trained
And the correct training methods can be used to
Improve the energy systems most used.
Eg training to increase lactate threshold,
VO2 max
Explain the structure shown in the diagram
(image)
For movement to occur, a message is transmitted from the brain, via the spinal cord & nerves and then on to the muscle.
Nerves are made up of bundles of neurons, or nerve cells.
The neurons that transmit impulses to muscles are called motor neurons.
A single motor neuron joins with many muscle fibres.
The motor neuron & the number of muscle fibres that it innervates is called a motor unit.
All muscle fibres will respond when the motor neuron is activated.
The muscle fibres will either not respond to an impulse, or respond once the impulse reaches a certain intensity & frequency
The A-band within the muscle fibre consists of: A.) Actin filament only B.) Myosin filament only C.) Myosin filament and the z line D.) Both Myosin and actin filaments
D.) Both Myosin and actin filaments
Describe the “All-or-none” principle
A single motor neuron joins with many muscle fibres.
The motor neuron & the number of muscle fibres that
it innervates is called a motor unit.
All muscle fibres will respond when the motor neuron
is activated. This is known as the “All-or-none” theory.
Explain the term oxygen debt.
What determines the length of the oxygen debt?
An O2 deficit is when the demand for O2 is
greater than the supply during exercise.
It takes time to deliver the required amounts of
O2 to the muscles.
Consequently, the anaerobic systems provide
the majority of ATP in the initial stages of exercise.
They do not rely upon O2 to resynthesise ATP.
Therefore at the end of exercise the body continues to have
increased ventilation to repay the oxygen deficit. The longer
the oxygen deficit , the larger the oxygen debt.
Describe the characteristics of fast and slow twitch fibres
The basic structure of muscle fibres is the same.
However they vary in relation to contraction time, the amount
of tension that they produce and resistance to fatigue.
A motor unit consists of only one muscle fibre type.
There are 2 main types. These include:
Slow twitch Fibres
They are also known as red (due to the presence of myoglobin)
and Type I fibres.
Fast-twitch fibres
They are also known as white (much paler as they contain little
myoglobin) and Type II fibres.
Types of fast twitch fibres
Type IIa
They possess partially aerobic characteristics
Type IIb
They possess purely anaerobic characteristics.
Explain the term Steady state.
Steady state is when the O2 supply = demand during exercise.
The required amounts of O2 are distributed to the muscles.
Therefore oxygen uptake (VO2) levels plateau.
