Advanced Anatomy & Physiology
Unit 5 – Stability and posture
Lesson 5.1 – Flexibility
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
Step 1 – Aims
This lesson will enable you to:



Describe the factors that affect flexibility
Explain the benefits of stretching
List the methods of stretching
Steps 2 – Factors affecting flexibility
Flexibility is defined as the amount of movement available at a joint or over a
range of joints. It is probably the most neglected aspect of fitness, and the benefits
of it are often realised too late.
Steps 3 – Factors affecting flexibility
So, the four key factors are:
Gender: most females are more flexible in the joints than most males
Temperature: an increase in temperature either induced by direct heat or a warmup can increase the range of movement of the joint and make the muscle more
pliable. Likewise a drop in temperature can hinder the stretch by up to 20%
Exercise history: an active person will be much more flexible than a sedentary
one
Age: people generally get less flexible as they get older (although it is possible to
improve flexibility at any age)
Step 4 – Activity
What are the reasons for stretching your muscles before starting any vigorous
exercise? Try to note down at least four reasons for doing this. Then move on to
the next step.
Step 5 – Benefits of stretching
By stretching gently, the body becomes more pliable and less prone to injury.
Flexibility is increased by stretching.
As you may have suggested, stretching helps to:







Reduce muscle tension and make the body feel more relaxed
Increase the range of motion of a joint
Prevent muscle strains: a strong pre-stretched muscle resists stress better
than a strong unstretched muscle
Prevent joint sprains
Reduce the risk of back problems
Prepare the body for strenuous exercise
Increase body awareness
May 2015
© Future Fit Training, 2015
Page 1 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility




Promote circulation
For females, reduce the severity of painful menstruation (dysmenorrhea)
Increase the learning, practice and performance of many types of skilled
movements
Reduce muscular soreness
Step 6 – Guidelines for stretching
The following are some useful tips that you can pass on to your clients regarding
stretching:







Always warm up before you start stretching exercises
Focus on what you're doing – feel the stretch
Work slowly and smoothly as you go into the stretch, and as you come out
– don't jerk
Concentrate on the muscle group that you are stretching
Maintain good body posture
Breathe normally and freely. As you move deeper into the stretch,
emphasise your exhalation
It is safe to stretch every day
Step 7 – The stretch reflex
The stretch reflex is a function of the nervous system and it helps to prevent injury.
Whenever a muscle is stretched, impulses are sent via sensory nerves to the
spinal cord. If the tension within the muscle is such that it is at risk of being
overstretched, impulses are sent to the muscle via the motor neuron, causing a
reflex contraction, which shortens the muscle.
You've probably heard of a 'knee-jerk reaction', and know that this has quite a
literal meaning. When the patella tendon is tapped lightly, the muscle spindles
running parallel to the muscle fibres stretch and alter their shape. This causes the
spindles to fire and send a message to the brain. As a result, nerve impulses make
May 2015
© Future Fit Training, 2015
Page 2 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
the quadriceps muscles contract and shorten, and this takes the tension off the
muscle spindles.
The faster the stretch is performed, the greater the magnitude of the reflex
response. This is why ballistic stretching (which will be explained later) is thought
to increase the risk of injury, as bouncing at the end of a muscle's range of
movement can increase the risk of muscle tearing.
For stretching to be most effective, muscles should be completely relaxed.
Stretching, therefore, is best done slowly.
Step 8 – Classifying stretches
Stretches can be classified in two general ways. Firstly, we can divide them based
upon what we are trying to achieve:



Preparatory stretching
Maintenance stretching
Developmental stretching
Secondly, we can divide them based on the method that is used for stretching:






Static stretching
Dynamic stretching
Ballistic stretching
Passive stretching
Active stretching
Proprioceptive neuromuscular facilitation (PNF)
Let us consider each one in turn.
Steps 9 – Preparatory stretches
Preparatory stretches are usually performed just after a pulse raiser or warm-up.
The preparatory stretches are stretches for the main muscle groups that are going
to be worked during the session such as the hamstrings, quadriceps, glutes and
gastrocnemius in a lower body workout. These muscles would be stretched
because they are going to be used.
They should be performed gently and held between 8–10 seconds. In order that
the heart rate does not drop too much during this time (losing the effect of the
warm-up), the stretches should be done standing.
Steps 10 – Preparatory stretches
Traditionally, preparatory stretches have been performed prior to exercise to
reduce the risk of injury. However, this practice is now being questioned in light of
emerging evidence that suggests that pre-stretching does not significantly reduce
the risk of injury.
May 2015
© Future Fit Training, 2015
Page 3 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
A common practice in the preparation for sports events is to use dynamic and/ or
ballistic stretching instead of static stretching. In light of the above lack of
evidence, this dynamic approach to pre-stretching is starting to be adopted by
everyday exercisers as well.
Step 11 – Maintenance stretches
If a muscle group has been continually contracted (for instance, if part of the
session has been dedicated to performing a large number of squats), then
maintenance stretches should be performed to get the muscles back to their
normal length. They may also help to alleviate potential soreness. A maintenance
stretch is usually held for between 10–15 seconds.
Steps 12 – Developmental stretches
Developmental stretches are aimed at increasing general flexibility, and are
therefore usually performed at the end of an exercise session.
These stretches should be performed passively using the individual's own body
weight, gravitational pull or pressure of hands in partner work. Therefore, lying on
the floor or in a seated position is best suited for developmental stretches.
It is important that the muscle being stretched is relaxed, as the position needs to
be held for at least 20 seconds.
Steps 13 – Developmental stretches
In general, the stretch can be broken down into two phases – an initial stretch,
taken to the point of tension and held until the muscle relaxes further, followed by
a further period of at least 20 seconds.
You will find that, after the first period, the tension that develops in the stretched
muscle, as a result of the stretch reflex, subsides. Once this has happened, the
limb can then be taken into a position that allows the muscle to be lengthened
further, thus increasing the stretch.
No pain or discomfort should be felt at any stage. The limb should not shake. If it
does then the stretch has been taken too far and should be released.
Step 14 – Static stretching
A static stretch is a slow, sustained stretch where the muscle is taken into a
lengthened position and held for a set period of time.
Static stretching is generally safe, and that is its most important advantage. Some
other advantages are that:

Little energy is required
May 2015
© Future Fit Training, 2015
Page 4 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility


It permits plenty of time to reset the sensitivity of the stretch reflex
Semi-permanent changes in muscle length are possible
Step 15 – Dynamic stretching
Dynamic stretching uses momentum to take the muscle through a full range of
motion but not beyond what the muscle would stretch to in a static stretch (unlike
ballistic stretching). The movements are also performed in a controlled manner to
prevent injury. Examples include lunging, squats, arm circles, lateral flexion and
spinal rotation. The movement should start using a small-range motion which then
builds, for example, by starting with partial squats and building to full squats. This
allows the muscles time to acclimatise.
Steps 16 – Ballistic stretching
As already discussed, ballistic stretching goes against the principle that stretching
exercises should be carried out while muscles are relaxed. Ballistics is generally
not to be recommended for clients, unless they are in training for specific activities.
Ballistic stretches are fast, bouncy and jerky movements, performed to gain
momentum in order to enhance the stretch by taking it through a maximal range of
movement. Because of this, they do not allow the muscle fibres time to adapt to
the stretch. They also activate the stretch reflex, increasing muscular tension.
Steps 17 – Ballistic stretching
There is also the possibility of minute tearing and scarring of the muscle fibres
which could cause a gradual loss of elasticity. Ligaments can also become
damaged from the speed of the movement, and this can subsequently lead to joint
instability.
However, some athletes and dancers choose to engage in ballistic stretching
exercises in order to improve flexibility and to develop dynamic flexibility – that is
strength of movement resulting from an initial effort. In activities such as karate
and ballet, ballistics are a normal part of training, as these sports require the
muscles to go through their full range of motion and beyond, at speed.
Step 18 – Passive stretching
Passive stretching is achieved by stretching the muscle, using an external force (a
partner or object) and is usually undertaken at the end of an exercise session or in
the early stages of physiotherapy. However, individuals should be careful not to
over-stretch.
It is especially useful when the muscle is weak, or when the antagonist muscle is
very tight. If stretching machines are used (as in physiotherapy), then the duration,
direction and intensity of the stretching can be measured.
May 2015
© Future Fit Training, 2015
Page 5 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
Because the power is supplied by an external force, stretches beyond the normal
range of movement are possible. For that reason, partners working together
should take care to apply the stretch correctly, and not too rapidly, to avoid risk of
injury.
Step 19 – Active stretching
Active stretching is achieved through the active contraction of the participant's own
muscles. It is achieved by contracting the muscles that oppose the muscle being
stretched. This then causes the stretching muscle to relax further. This is due to
reciprocal innervation (if a muscle contracts, then its antagonist will relax).
Step 20 – PNF stretching
Proprioceptive neuromuscular facilitation (PNF) was originally developed as a
patient rehabilitation procedure in physical therapy. It is a generic term for a
number of different techniques, which work by alternately contracting and relaxing
muscles, capitalising on various muscle reflexes to achieve a greater level of
relaxation during the stretch.
There are two common PNF techniques:

The contract-relax (or hold-relax) technique
This begins with the athlete's tight muscle group – the hamstrings, for
example – in a lengthened position. The muscles are stretched to the point
of tension and held for approximately 10 seconds. They are then contracted
isometrically and as fully as possible for 6–10 seconds against the
resistance of a partner. The participant then relaxes and the stretch is
increased within 10 seconds to the point of tension; this should result in the
leg being moved further than it was at the start of the stretch. This can then
be repeated a further 2–3 times.

The contract-relax-antagonist-contract (or hold-relax-contract) technique
This technique is similar to the contract-relax technique except that after the
relaxation phase, the antagonist of the tight muscle group (the quadriceps
in the case of the hamstrings) is actively contracted. This works on the
principle that if the antagonist contracts, the agonist will be fully relaxed.
This contraction can also be effected with the aid of a partner. The whole
procedure is then repeated.
Step 21 – PNF stretching
PNF stretching should only be attempted when the body is completely warmed
and relaxed, and provided the partner involved is competent in helping with the
stretch. Resistance should be provided in the isometric phase and mild assistance
in the static stretch phase.
May 2015
© Future Fit Training, 2015
Page 6 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
PNF techniques are claimed to:



Be the most successful method for developing flexibility
Enhance active flexibility and help establish a pattern for coordinated
motion
Help reset the stretch reflex level
However, there is some risk of muscle injury and you should therefore not instruct
clients in these techniques unless you have received specific training in PNF.
Step 22 – Safety tips – when not to stretch
With all gym or exercise-to-music class instruction, you should always be aware of
the state of your client's health before advising any kind of exercise. The same
applies to stretching. For example, someone who is recovering from a bone
fracture should not be encouraged to stretch her muscles.
Try to name two other conditions that would make you warn against stretching.
Feedback: Clients should not stretch muscles if:






There has been a recent bone fracture, sprain or strain
The range of motion is in some way limited
The joint is inflamed or infected
They have signs of osteoporosis
They experience pain when the joint is moved or the muscle stretched
They are suffering from certain diseases of the skin or blood vessels
Step 23 – Activity
Match the definitions on the right with the correct term on the left.
Static stretching
Ballistic stretching
Passive stretching
Active stretching
Dynamic Stretching
PNF
fast, bouncy and jerky movements, performed in the endrange position
stretching to the farthest point and holding
uses stretching–contraction–relaxation techniques
uses an external force, such as the muscles of a partner or
a machine
controlled movement through a full range of motion
performed by contracting the opposing muscle to cause
further relaxation
Step 24 – Activity
What are the differences between active, passive and static stretching?
Feedback: Active stretching is performed by contracting the opposing muscle to
cause further relaxation in the muscle being stretched. This contrasts with passive
May 2015
© Future Fit Training, 2015
Page 7 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
stretching, in which an external force is used to increase the stretch. In static
stretching, the stretch is taken to the farthest point and held.
Step 25 – Summary
Now that you have completed this lesson you will have a better understanding of
the following:
Flexibility varies with age, sex, temperature and the history of activity of the
individual.
Stretching helps to:






Reduce muscle tension and make the body feel more relaxed
Increase the range of motion of a joint
Prevent injuries such as muscle strains. A strong pre-stretched muscle
resists stress better than a strong unstretched muscle
Prepare the body for strenuous exercise
Increase body awareness
Promote circulation
Methods of stretching are ballistic, static, active, passive and PNF (proprioceptive
neuromuscular facilitation).
We can also divide stretches based on what we are trying to achieve, that is:
preparatory stretches, maintenance stretches and developmental stretches.
May 2015
© Future Fit Training, 2015
Page 8 of 9
Advanced Anatomy and Physiology
Lesson 5.1 Flexibility
May 2015
© Future Fit Training, 2015
Page 9 of 9