Uploaded by Deborah Brewer

Muscles in exercise physiology

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Sport and Exercise Physiology
Muscles
Muscle Types
1. Smooth Muscle
–
–
Involuntary muscles – not under direct conscious control
Walls of blood vessels, internal organs (GIT)
2. Cardiac Muscle
–
–
Heart only – not under conscious control
Controls itself
3. Skeletal or Striated Muscle
–
–
–
–
Under conscious control
Attached to and move the skeleton
Make up the Musculoskeletal System
Can you name a few??
Definition
• Muscle is a contractile tissue
which brings about movements.
• Muscles can be regarded as
motors of the body.
BASIC PROPERTIES
• IRRITABILITY:
– Sensitive to stimuli
• CONTRACTILITY:
– When stimulated, the contracts lengthwise
leading to its shortening
• EXTENSIBILITY:
– Once stimuli removed, the muscle fibers return to
their original length.
• ELASTICITY:
– Muscle assumes a desired shape.
The Musculoskeletal System
Activity
• In Groups discuss what muscles you think
equestrian athletes use:
LO 2 & 3
The Musculoskeletal System
http://www.shapesense.com/fitness-exercise/muscle-anatomy/
Muscle Actions
Types of Muscle Action
 Isometric
– Muscle exerts force without changing length
– Pulling against immovable object
– Postural muscles
 Dynamic (isotonic)
– Concentric
 Muscle shortens during force production
– Eccentric
 Muscle produces force but length increases
 Associated with muscle fiber injury and soreness
Muscle Actions
Isometric and Isotonic Muscle Actions
Eccentric / Concentric
• Somebody perform a squat:
– What is happening on the way down?
– What is happening on the way up?
• Somebody perform a press-up:
– What is happening on the way down?
– What is happening on the way up?
Summary of Muscle Actions
LO 1
Types of Muscle Contractions
Dynamic exercise = change in muscle
length creating joint movements.
Rhythmic cycles of contraction and
relaxation
•concentric
•eccentric
LO 1
Types of Muscle Contractions
Isometric (static) exercise = constant
muscle length and increased tension –
Joint angles do not change.
Discuss in pairs what type of contractions occur when you ride.
Anatomy of Skeletal Muscles
Muscle Contractions
Now
in pairs
yourvideo
answers
to prepare
Watch
the discuss
following
& answer
thefor a
Kahoot quiz
questions provided
Go to www.kahoot.it
Muscle Fibre Contractions
• α-motor neuron
connects with
numerous muscle fibers
• Excitation – Contraction
Coupling (1-3)
• Role of Calcium Ions (45)
• Myosin Cross Bridge
formation and the
sliding filament theory
(6)
• Adenosine Triphosphate
(ATP) is needed to
power this process –
broken down by
enzyme ATPase
• Muscle Relaxation (7-9)
LO 1
Muscle Fibre Types
• Two types different speeds of shortening and ability to generate maximum
force
Type of
Muscle
Fibre
Speed
AVG % in
to reach Muscles
peak
tension
Forms of
Myosin
ATPase
Sacroplasmic α –
reticulum (SR) motor
Development neuron
Aerobic
Endurance
Type of
Activity
Type I
110ms
50%
Slow
form
Low
Innerva
tes
≤300
muscle
fibers
High
lowintensity
Type IIa –
25%
Type IIx –
25%
Type IIc –
1-3%
Fast form High
Innerva
tes
≥300
muscle
fibers
Low =
Anaerobic
High –
intensity
Type II
50ms
(Type
IIa, Type
IIx and
Type IIc)
Recruitment of Muscle Fibres
• Principle of orderly recruitment:
Motor units are ranked e.g muscle with 200 motor units = number 1200 – very fine contraction recruits No1 only, as contraction
increases 2,3,4,5etc = recruited
• Skeletal Muscle contraction goes through progressive recruitment
Type I
Type IIa
Type IIx
Fibre types and success in sport
• In Groups discuss which type of muscle fibre
would be best for the following Sports areas
(as allocated)
a.
b.
c.
d.
Team Sports
Endurance Sports
Sprints
Strength and Power Sports
• Feedback to the class your thoughts
LO 2
What about Equestrian???
Testing Muscle
Strength
• Isometric Testing:
– Tests strength at a particular angle of the joint.
– Determines parameters – maximal force, maximal torque and rate of force
development (RFD).
– Poor relationships between isometric (static) and dynamic performance
– Uses tensiometers, strain gauges and force transducers.
• Isoinertial Testing
– Uses external weights
– Dynamic contractions are tested
– Limitation = great motor control required to lift weights – increase the risk of
injury
– Maximal Concentric Strength is measured
– Uses test involving a low number of repetitions – typically 1-3 repetition
maximum (RM)
– 1RM regularly used
Testing Muscle Endurance
• Isoinertial Testing
– Subject’s own body mass provides the resistance.
– Uses tests such as Curl-up, Press-up and Chip-up
– Athlete’s perform as many of these exercises as
possible
Aerobic Vs Anaerobic Training Effects
O
Aerobic
2
• Type I fibres increase in size and
number
• Within the Muscles Fibres:
1. red in colour (high myoglobin
content) – increase
myoglobin by 75-80%
2. surrounded by many
capillaries – increases by up
to 15%
3. numerous mitochondria –
increase by 15%
4. low glycogen content (they
also metabolize fatty acids and
proteins, which are broken
down into the acetyl CoA that
enters the Krebs cycle)
LO 1
O2
Anaerobic
• Type IIa and Type IIx
increase in size and number
• Within the Muscles Fibres:
1.
2.
3.
4.
Whiter in color (low
myoglobin)
surrounded by few
capillaries
relatively few mitochondria
high glycogen content (they
have a ready supply of
glucose for glycolysis)
Effects of Resistance Training
• Strength – increases 25-100%!!!????
• Hypertrophy
– Transient Hypertrophy – Immediate increase in muscle
size after exercise– goes within hours of exercise
– Chronic Hypertrophy – increase in size from long-term
resistance training = structural changes in the muscle.
Results in:
• In increases in size to individual muscles fibres = fibre
hypertrophy
• Increase in number of muscle fibres = fibre Hyperplasia
• Training disrupts the sarcomere Z-lines resulting
in fibre protein remodelling (Shepstone et al
2005)
LO 3
Resistance Training
• Considerations:
– What major muscle groups need training
– What type of training should be used to achieve the
desired outcome
– What energy system should be stressed
– What are the primary sites of concern for injury
prevention
– Numbers of sets for each exercise
– Rest periods between sets and exercises
– The amount of resistance, repetitions and velocity of
the movement.
LO 3
Resistance Training
• Strength
–
–
–
–
Involves repetitions of concentric and eccentric actions
Large muscles groups – smaller muscle groups stress first
High-intensity exercises are done before low intensity exercises
When athlete can perform current workload at or above the desired
number of reps – increase load by 2-10%
– Focuses more on Eccentric contractions
• Hypertrophy or power
– Uses the same principles but athlete works at a higher 1RM % and
performs increased amounts of sets and/or works at a faster pace
• Endurance
– Uses the same principles but uses a light load (weight), increased
repetitions and works at a slow pace
LO 3
Next Week – Respiratory System
• Before then in two groups:
• Group 1 – Investigate what the Conducting
zone of the lungs is and what it is made up of?
• Group 2 – Investigate what the Respiratory
zone of the lungs is and what it is made up of?
You will report this back to the class next week!!
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