Skeletal or Bony System : This system consists of a large number of bones that form a structure called skeleton. The skeleton serves the purpose of a strong framework for the attachment of various muscles of our body and also serves as a source of protection of important organs of our body, such as brain, heart, lungs, liver, kidneys, etc. It gives shape to the body. Its bones serve as levers in doing work and the bone marrow found inside the bones manufactures some of the cells of the blood.
The skeleton as shown in Fig. consists of :
(i) Skull bones
(iv) Shoulder girdle bones
(v) Bones of upper limbs
(vi) Pelvic bones
(vii) . Bones of lower limbs
These bones are connected together to form joints. Joints are held firmly together by strong white fibrous bands called ligaments (See Fig.). In some parts of the body, where an elastic but strong substance is required, as in nose, cartilage takes the place of bones.
The joints of the body can be classified into three main categories, i.e.
1. Immovable joints as in the skull,
2. Slightly movable joints such as between he bodies of the vertebrae, and
3. Freely movable joints, such as shoulder, hip joints, etc.
These joints enable us to perform movements like :
(a) Flexion and Extention
(c) Elevation and Depression
(d) Abduction and Adduction
These movements of the body are performed by the bones with the help of muscles that are attached to them.
Effects of Exercise on Skeletal System :
As a result of exercise, bones have to be moved to various positions. These movements are made possible due to the provision of joints in the body. Therefore, during exercise the joints have to bear a lot of stress, which puts a lot of strain on its ligaments that exert a binding force and the cartilages, which are the paddings in between the bones. This strain is borne by the ligaments and cartilages up to a certain limit but when the strain exceeds a limit, these get injured. Excessive strain can also cause the fracture of a bone. Due to the injury of ligaments or cartilages or both ligaments and cartilages, the malfunctioning of the joints takes place. It leads to pain and swelling in the area. If this malfunctioning is allowed to continue for a long time, it can lead to a deformity of the joint.
Effects of Regular Exercise
The effects of regular exercise over a considerable period of time can be enumerated as under :
1. Through regular exercise, some postural defects of the body may be removed or minimized.
2. Regular exercise helps maintain the flexibility of ligaments and cartilages which helps maintain the proper functioning of the joints.
3. In the growing stage of our life, our bones become slightly longer and their shape may also undergo a change.
4. Our bones become healthy and stronger and can tolerate greater strain.