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: Cardiac muscle in the heart Smooth muscle in the organs 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.

Measuring the size of mass that can be lifted using the thighs Suggest how you could test the strength of your quadriceps. Measuring the size of mass that can be lifted using the thighs

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