Investigating muscle strength
Aseel Samaro
Investigating muscle strength
 The heart is odd one out
 The heart is made from cardiac muscle
 The bicep muscle (in the arm), the calf muscles ( in the legs) and the
diaphragm (in the chest) are types of skeletal muscles.
Introduction
 Muscles make up approximately 40% of an adult’s body.
 One type of muscle is skeletal muscle, attached to the
skeleton.
Athletes work hard to:
Strengthen specific muscles
Train them to tire less easily
 Bodybuilders work on their muscles in a different way and
train to make them bigger
The main muscles of the body
There are three types of muscle:
1. Cardiac muscle in the heart
2. Smooth muscle in the organs
3. Skeletal muscle attached to the skeleton
Skeletal muscles
 Skeletal muscles allow you to move.
 They are attached to bones by tendons.
 As the muscles contract: they pull on tendons causing the bones around a joint
to move
 You have over 600 skeletal muscles, which are all involved in moving parts of
your body.
 You may not notice the movement caused by some of these muscles, such as:
tiny facial muscles that cause minor movements.
The main skeletal muscles
Name the three types of muscle and state where each is
found.
Name three muscles of the arm.
WORKSHEET
Did you know
The heart is made of muscle.
But this is different to the muscles attached to your skeleton.
Heart muscle (cardiac muscle) contracts approximately 70 times every
minute for your entire life and it does not tire.
Muscles in action
 When a muscle pulls, it is contracted  This means the muscle gets
shorter and fatter.
 When a muscle is not contracted, it is relaxed. When a muscle
relaxes, it returns to its original size.
Most actions use many muscles.
For example, when walking up stairs you use your:
calf muscles
quadriceps (thigh muscles)
abdominal muscles.
If you move your upper body as you walk, you use many more muscles.
Describe the differences between a contracted and a relaxed
muscle.
contracted muscle: shorter; fatter
Explain how your calf muscle causes your heel to lift.
The calf muscle contracts, pulls on a tendon attached to a bone in the heel and lifts the heel
Measuring muscle strength
 By exercising you can increase the strength of muscles.
 Professional sportspeople consider their training very carefully to
ensure that they target specific muscles.
 They also test the strength of their muscles frequently to check their
progress.
 These scientific tests must be carried out fairly
so that measurements can be compared over
time.
 This figure shows a device to test the strength
of the forearm and hand.
 The person squeezes the handle as hard as
they can. The result is then displayed as
a force (measured in newtons).
A basketball player wants to compare the strength of his forearm
with that of a footballer. Predict who would have the most strength.
Suggest how you could test the strength of your
quadriceps.
Measuring the size of mass that can be lifted using the thighs
Thank you