1. Properties of Skeletal Muscle
1. EXTENSIBILITY
= The ability of muscle tissue to lengthen when
contracting (produce movement)
2. ELASTICITY
= The ability of muscle tissue to return to its normal length
once it has been stretched
3. CONTRACTILITY
= The capacity of a muscle to contract forcibly
(excitability)
 All three are essential for body actions: locomotion, co-
ordinated movement, posture and facial expressions.

2. Functions of Skeletal Muscle
1. MOVEMENT
Antagonistic Muscle Action
2. SUPPORT & POSTURE
Muscles are always in a constant state of slight
contraction (Muscle Tone)
3. HEAT PRODUCTION
In breaking down glycogen (needed for energy
and muscle contraction) heat is released.
Therefore the body becomes hot when we
exercise.

3. Why Warm-up and Cool-down?
 Purpose = Prepare & Prevent
 Must be specific to the sport and
muscles used.
 3 Stages:
1. Raise HR
– increase O2 delivery
– increase body temp.
2. Mobility
– full range of movement via stretches
eg. Lunges
3. Sport/Skill Specific
– practices related to the sport
eg. Passing in rugby
 Purpose = Prevent any unnecessary
discomfort
 2 Stages:
1. Active Recovery
– Light/continuous exercise
– Keeps the HR raised to allow O2 to
be flushed through the muscle
2. Stretching
– Muscles are warm so stretches are
easy
Warm-Up Cool-Down

4. Physiological effects of a warm-up and
cool-down on the skeletal muscle
system.
↑ Muscle Temperature
↑ Extensibility of muscle
fibres
↑ Elasticity of muscle
fibres
↓ In muscle viscosity
(resistance)
↑ Contractility & speed of
muscle contractions
↑ Oxidisation of the
muscle
↑ Removal of Lactic Acid
↓ DOMS
↑ Flexibility
Warm-Up Cool-Down

5. Benefits of regular physical activity
on the skeletal and muscular
systems.
 Increased Bone Density
 Articular Cartilage
Thickens
 Ligaments stretch slightly
allowing a greater range of
movement at the joint.
 Increased Muscle Mass
due to HYPERTROPHY
(enlargement) of muscle
fibres
 Tendons Thicken
 Improved Flexibility
 Increased Extensibility
 Increased Elasticity
 Increased Contractility due
to HYPERPLASIA
(splitting) of muscle fibres
Skeletal System Muscular System

6. PREP
The impact of different types of physical activity
on
the skeletal and muscular systems
Read Pages 41-42
Activity 20:
‘Participation in sport is dangerous and
damaging to the musculoskeletal system’.
Write an extended answer (minimum 500 words)
showing how far you agree with this statement.